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Mini Torii SE Amplifier (Read 74637 times)
brians7
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Mini Torii SE Amplifier
04/16/09 at 05:30:04
 
I recived my amp today.  And all I can say is wow!!  This little amp can easily replace my other amps.  With my Klipsch La Scala speakers I never felt like my Decware SE84CS amp never quiet had the musle to drive the 15in woofers in the speakers.   The Mini Torii has plenty of head room.  It sounds absolutly amazing and I have not had a better sounding amp.   I was trying to decided between this amp and a McIntosh MC2155.  I know that I made the right choice, because I have tried several Mac amp in the past and non of them sounded this good.    I know that steve doesn't like us talking about watts but I never felt like the 2 watts I got from my SE84CS was enough, but I know that how ever many watts this 3-6 whatever this amp has is plenty enough, to make me grin from ear to ear. And it sounds absoultly amazing! Wait a minute I already said that.  But it sounds absoultly amazing...  Brian
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Lon
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Re: Mini Torii SE Amplifier
Reply #1 - 04/16/09 at 10:52:14
 
Hey, thanks for weighing in B, I know many  have been waiting for a review!
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Rivieraranch
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Re: Mini Torii SE Amplifier
Reply #2 - 04/16/09 at 12:54:01
 
When you calm down, I would like to know what the impressions are between using a 6V6 and 6L6 in this amp and the different voltage regulator tubes.
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Doorman
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Re: Mini Torii SE Amplifier
Reply #3 - 04/17/09 at 00:13:45
 
Brian: Interesting that the mini Torii seems to have more muscle than your Select. I've a Select myself, and have been wondering about the SE34-I, but your post has me wondering if the mini Torii might fill the bill.
Hmmm---!
Don
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Rivieraranch
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Re: Mini Torii SE Amplifier
Reply #4 - 04/17/09 at 22:54:18
 
What about impressions of the different tube combos?
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brians7
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Re: Mini Torii SE Amplifier
Reply #5 - 04/19/09 at 03:30:56
 
( Interesting that the mini Torii seems to have more muscle than your Select. I've a Select myself )         It doesn't seam to have more muscle.  It diffently has more.  I used Select with a pre-amp mostly and tried several times to use it without, but I was always wanting more power no matter how I used it.  I am using the mini torii without a pre-amp now and it doesn't seem to need a pre-amp at all.        

( What about impressions of the different tube combos? )       I have had no success with the 6L6.  I had a pair and tried to use them and only one worked.  One 6L6 lit up and played fine in one channel the other 6L6 didn't light up at all the other tubes did but nothing came out of the speaker so it must be a dud. I Put the 6V6 back in and no problem with the amp.  I have tried Westinghouse 6V6GT made in Canada.  My first impression the base is very tight and the highs are brighter than the tubes I am using now.  Which is 5992.  This tube still sounds very controlled in the base, and the highs are not quite as bright. It also has a little more mid range. They both have a very simular sound. I will try 6F6 and 6k6 tomorrow.   Brian
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Brian
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Re: Mini Torii SE Amplifier
Reply #6 - 04/19/09 at 10:06:59
 
This is to me, Decware's most exciting amplifier.  I will be eager to follow this report.
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Rivieraranch
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Re: Mini Torii SE Amplifier
Reply #7 - 04/20/09 at 03:51:16
 
Nix the 6L6 for now, then.

Somebody please send him a pair of 6L6GC's so he can try the amp with them.

What about the input tube, can you use something other than the 12AU7?
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brians7
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Re: Mini Torii SE Amplifier
Reply #8 - 04/20/09 at 07:30:09
 
I tried a pair of National Union 6F6GT with a pair of the OC3's.  The mid range seems a little relaxed not sweeter though.  And it hardly has any base compared to the 6V6.   If you turn up the volume you can get a little base out of it.  But with the 6V6 it was tight and full at any volume.  It looks like the 6V6 is the winner.  I will try the 6F6 with the OA3's to see of that helps with the base.  The input tube I am using is a RCA6189 black plate.  I ordered a set of Ruby 6L6's.  I love the ruby's EL34's in my VAC amp. Which is for sale on audiogon if anyone wants to buy it. Talk to yall later.  Brian
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brians7
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Re: Mini Torii SE Amplifier
Reply #9 - 04/24/09 at 14:42:59
 
I put the OA3's back in with 6F6's some of the base retuned, but it still doesn't equal the 6V6's.  I am trying the RCA 1611 which is a 6F6 variant made for US Navy SOS transmitter.  The sound is very similar to the 6F6 maybe a little thinner and seems faster. Brian
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Rivieraranch
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Re: Mini Torii SE Amplifier
Reply #10 - 04/25/09 at 15:08:07
 
I am interested in whether you can use another input tube other than the 12AU7.

Also, why are you futzin' around with those lame 6F6 variants. From what I have read the amp is better suited for the 6V6 and 6L6 family?

As to the lower vs. higher voltage regulator tubes how do they affect the sound with the 6V6 in place?
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brians7
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Re: Mini Torii SE Amplifier
Reply #11 - 04/26/09 at 19:18:31
 
I got the Ruby's.  I used them with the OA3'S.  The amp has a much fullier and richer sound than with the 6F6's.  With most of the base retuning.  I will have to use the 6V6's again and compare it to the 6L6. The amp sounds pretty nurtral on its on, but with the 6L6's it is easier to tell that it is a tube amp.  With the 6V6 tubes it sounded very similar to a class A solid state amp.  One thing I forgot to mention the amp has been absolutliy dead quiet between tracks you would not even know that it was on.  Almost any other amp I have used had some noticable hiss or hum it was just something I though I had to live with being that my spekers are 104 db sensity.  Brian
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Rivieraranch
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Re: Mini Torii SE Amplifier
Reply #12 - 04/27/09 at 04:03:43
 
I am curious whether an OD3 would help out with the bottom end. Also how would a regular 12AU7 sound on the input? I understand that the 6189 has a higher plate voltage. Can you use another input tube other than the 12AU7 family?
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Lon
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Re: Mini Torii SE Amplifier
Reply #13 - 05/01/09 at 14:26:14
 
Brian, are you enjoying/using the Treble Cut circuit?  I had this added to the Integrated Steve built me some weeks back and I find it very very very useful for musical enjoyment!
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Rivieraranch
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Re: Mini Torii SE Amplifier
Reply #14 - 05/02/09 at 19:48:07
 
Could you give us a Saturday update? Are those RCA 6189's triple micas?
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frank
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Re: Mini Torii SE Amplifier
Reply #15 - 11/21/09 at 22:29:17
 
I now have more than a 1,000 hrs on my mini.....and
With more than 50 active years involvement in audio, I
feel this is the best sounding amp you can buy.
Plus you have an ability to play with the sound more than any amp
I know of. I am now trying Sylvania chrome domes 6v6's with OC3's....
great sound, very open....waiting on tunsol 6l6's. Tried ken rad metal
6l6...and OC3's...good bass...slightly thick....

THE BOTTOM LINE.....this is a world class amp of the greatest
that you can buy regardless of price.
THE ONLY amp I have seen that you can listen to..all day and every day and crave more....at least to this old fart's ears....;-)f

regards,
frank
 
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Lon
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Re: Mini Torii SE Amplifier
Reply #16 - 11/21/09 at 23:48:49
 
That's the way I feel about my Torii Mark II. Smiley  Decware has more than one excellent amp option!
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frank
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Re: Mini Torii SE Amplifier
Reply #17 - 11/22/09 at 00:17:35
 
Sorry....you are so right..I also have a taboo and several other
works of art from Steve.....I was speaking somewhat in awe
of what I have been hearing. Having been blessed in life
I have owned many of the best......
I am fortunate to not have to work so I listen every day......
and this particular product has tripped my trigger better
than any I can remember......
"music lives forever, people don't, listen now.......;-)f
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Steve Deckert
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Re: Mini Torii SE Amplifier
Reply #18 - 11/22/09 at 01:46:39
 
Hi Frank!  Welcome to the forums!  I couldn't be more pleased to see you drop in here.  As we've had several nice conversations over the years and I'm fully aware of your audio resume, the members here who don't yet know you will enjoy learning from your experiences.

For example, imagine the fix one would have from discovering that their special little $1500 amplifier actually sounds better than the "stereophile class A rated / best of show" amplifiers on the cover!  Trust me, it's a great natural high.

Also REGARDING INPUT TUBES for the MINI TORII,  the 12AU7/5963's that are shipped with the amp are just to get you warmed up.  I really voiced the amp around the 12AT7, and a great NOS 12AT7 in the Mini Torii simply kicks ass.

-Steve  [smiley=peanuts42.gif]
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frank
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Re: Mini Torii SE Amplifier
Reply #19 - 11/22/09 at 18:09:54
 
Thanks Steve...you are so right about the 12at7's.....
currently using mullard's, which is my favorite
after trying various 12au7's and 12ax7's.
All I can say is there's something about this amp that enraptures
me and my feet can't stay still................
;-)f

I feel about audio as I do about photography...there's
a picture of your pre production statement pre amp insides
and pictures of arizona on my gallery.......

http://gallery.me.com/flaneb#100280
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Chris K
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Re: Mini Torii SE Amplifier
Reply #20 - 11/22/09 at 20:04:32
 
"pre production" ? Steve you holdin out on us loyal DecFesters, or did I miss something? Undecided
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frank
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Re: Mini Torii SE Amplifier
Reply #21 - 11/23/09 at 23:53:23
 
I will say, I have never heard a better pre amp......very unique with
special  construction; the output tubes are at the output jacks
also as with the mini torii....It is so transparent that the smallest
change anywhere in the chain can be heard.
I have always felt you could use the mini as a form of test equipment...

;-)f
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Rivieraranch
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Re: Mini Torii SE Amplifier
Reply #22 - 11/24/09 at 13:22:35
 
The fidelity and presence that this unit gives the music is awesome. For example, if it is loud, I can go out of the music room and into the other part of the house and still hear wonderful, credible sound. I had a Paul Chambers Mosaic Select set playing and it seemed as if somebody was actually playing a trumpet in my music room.
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frank
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Re: Mini Torii SE Amplifier
Reply #23 - 11/24/09 at 19:45:05
 



They are stacked for the picture.....I have not been able to find a better
combo......
regards
;-)f
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« Last Edit: 11/30/09 at 17:01:15 by Steve Deckert »  
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frank
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Re: Mini Torii SE Amplifier
Reply #24 - 11/24/09 at 19:46:25
 
sorry I was unable to attach the photo.......
frank
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #25 - 04/11/11 at 01:10:50
 
Hello everyone,

I also happen to own a Mini torii now. I have had it here for a little over two weeks. It is such a strong presence in the house that I am not sure who has whom anymore, has it got me or have I got it? The living room is slowly being remorphed around its needs, now that I can finally hear music and understand what 70% of audiophile talk was about. All this time I have been hearing about veils being lifted from the music and I thought I knew what that meant.
I have just ordered a few pairs of tubes from the Tubestore.com (they are based in Ontario I think. Myself I am in Montreal) So by Tuesday I should be able to experiment with 0b3 and 0d3 voltage regulators and a pair of mullard 12at7.
So far I have been listening to a pair of 6v6 genalex (reissued) with the stock tubes (except for the 6X4 regulators, which I had to replace with something obscure, since one of the stock died out in the early hours). The Genalex felt so thin on the bass that I decided not to use them anymore and returned to the stock 6v6, which have tighter more present bass, albeit a less intriguing midrange. The Genalex I find sound particularly lush and detailed. The stock make rock music more interesting.
I tried a pair of (reissue) mullard 12ax7 and also tungsol 12ax7 and they were way too noisy. Gold pin Electro harmonix 12ax7 were dead quiet but a little uninvolving.
I built my own speakers. Audio Nirvana 10 inchers, they must have a 96db sensitivity. Their design is pretty forward and my patience is vast, so they are extremely well built and performing to specs.
Now I wish I could manage to post a pic, I don't seem to work out the protocol...
here : http://www.flickr.com/photos/61617415@N02/5608265188/

http://www.flickr.com/photos/61617415@N02/5620701732/lightbox/
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« Last Edit: 04/15/11 at 01:16:49 by Raduschka »  
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #26 - 04/11/11 at 01:35:04
 
...can anyone please tell me if I can switch between the 0a3 and the other voltage regulators without any further consideration? Like I said, I ordered a pair of 0c3 and od3s. Thank you
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #27 - 04/14/11 at 02:42:44
 
after extensive listening I can confirm that a pair of nos RCA 0d3 regulators have made the bass much fuller, more present, easily audible, in one word: satisfying. It is not an issue anymore. The sound is indeed punchy and resembles a solid state amp, as much as beautiful tubes can resemble that. I am using that comparison to say that it offers the best of the two worlds, it would be more exact to say that it sounds like a well built tube amp:-)
I was worrying that perhaps some detail and midrange had been lost after the addition of the bass, but I believe now that it was a mere belief ( along the lines: hmmm, the bass is too good, surely I can't have it all). But
it turns out I can.
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ZYGI
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Re: Mini Torii SE Amplifier
Reply #28 - 04/14/11 at 14:24:32
 
Raduschka,

Sorry I didn't see your post earlier, couldn't have helped you with your question anyway, maybe that is why no one else responded.....

Is the Torri new, or a used purchase. If new then the bass will go in and out as well as every other aspect of the amp until it burns in.

Welcome to the forum...
ZYGI
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #29 - 04/14/11 at 19:20:22
 
thank you ZYGI,

my Mini torii is brand new, I have had it for two or three weeks. Is it still settling in? I noticed the bass going in and out and up and down...

but with a pair of 0d3 instead of the 0a3 the bass became a lot more present and full, whereas before it was...thin. I do have to think hard to put words on those perceptions..
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« Last Edit: 04/14/11 at 19:22:19 by Raduschka »  
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ZYGI
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Re: Mini Torii SE Amplifier
Reply #30 - 04/14/11 at 22:38:51
 
I have a hard time putting things into words as well...and English is my native language.

The amps will do that, I found that once the mini is broken in and well seasoned, you can't make the bass sound bad. It doesn't seem to care what load you put to it, its spot on.

Your links to your photos are private, I can see them.....

ZYGI
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #31 - 04/15/11 at 03:23:48
 
hello again Rivieraranch,

I can now say that all things equal, the 0d3 are the regulators that make the amp sound best for me, they make it keep Steve's promise of great bass lines that you can follow easily. They saturate the sound in a way that makes the amp sound 'big', in my understanding of the word. They make it sound like my 70 watt jolida, but without the crap.
The only regulator I haven't tried yet is the 0c3.
Also, placing little pieces of rubber between the spikes and the floor helped a lot with the low end.

Regards
Radu
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Re: Mini Torii SE Amplifier
Reply #32 - 04/17/11 at 17:27:47
 
Raduschka,

Which Jolida 70 watt amp do you have?  Is it the 801A?  If so, I am curious about the "crap" you are hearing versus what you are hearing in the Mini Torii as I have the 801A as well.

Thanks.
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #33 - 04/17/11 at 18:10:41
 
hello Mac5u, I didn't mean to put down YOUR Jolida, I was just referring to mine... I guess now I have to stand behind my words. I know someone who has the Joilda 801...B I think, anyway, the version that has the bias pots on the bottom rather than the top. His was heavily modified (point to point internal silver wiring and everything else you can read about on Bill Baker's Response Audio site). He uses vinyl and is quite happy with the sound (driving a pair of hungry dynaudios).
I have the A version, with the pots on top and no modification other than selector pot bypass directly to volume pot, which made one hell of a difference in imaging capabilities.
So, on to the 'crap'. And I mean this with a grain of salt.
I used to drive a pair of Triangle Antal xs speakers with it. Those retailed for 3000$ new and won the diapason d'or back in 2003 or so, maybe 2002.  The Jolida could not get the bass right under any circumstance.  It was inarticulate when there was a lot of it in the recording, and absent when there was just enough to be reproduced. I had way more bass in my akg headphones and was going: ah, so this is the bass line of this song! Could not hear it in the system. Everything else seemed to be so so with the Jolida. In and of  itself it did a decent job of imaging (after the selector pot was taken out of the way). The midrange was ok, highs were ok, music was powerful. Rock music sounded good. I listened to it then on my Audio Nirvana 10inchers and I am selling both my Triangle speakers and my Jolida. After I got the Audio Nirvana, the Triangles sound as if I covered the Nirvanas with a thick wool blanket, and I am not exaggerating. After I got the Mini Torii, the Jolida sounds kind of the same. The imaging on the Mini Torii is simply incomparable, so are the timbre, the bottom end, the midrange, the highs etc etc.... What can I say? The Jolida hits hard, but the torii hits right.  I suppose I could use Steve's idea of the first watt that sucks. Some people buy the Jolida for around 700 $ (the aforementioned person got his for 800$ after full modification, which must have cost around 1000$ by itself) . I heard that they sound good once modified, but why bother when you can get a mini torii for exactly the same price for which  I bought my Jolida new, that is 1500$. of course here in Canada the torii ended up costing 1800$.
If the Jolida was a steal in terms of price, I would not be harsh on it, but it camoflages itself as high end and I find it deceiving. I still like my hybrid Jolida 301 or so, which retails for 400$ and which some would call crap. I like the way it sounds for the money Smiley

With the 801 it is the opposite.
I am sure there are a million products out there falling in all of these price per value categories. And it is all pretty relative, as I am sure the Mini Torii can be improved upon. In terms of sound, yes.

I regret having used the term crap, I was eager to put down what had let me down. I thank my Jolida 801 for a few nights of pleasure and as we part I will not regret the many hours of trying hard to make out the bass lines on old Genesis albums.
ps: if you have power hungry speakers you can try cheap effective and fantastic sounding fullrange drivers from Audio Nirvana, commonsense audio, David Dicks is a great guy to email questions to. You can build your cabinets easily and cheaply and they are so simple that you can't go wrong.
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« Last Edit: 04/17/11 at 18:19:20 by Raduschka »  
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #34 - 04/17/11 at 18:28:00
 
...the Torii sounds transparent in comparison with the Jolida. You can hear subtle differences. For exemple, a mono recording of the Miles Davis quintet (I can't find it in my massive pile of cd's unfortunately). I tried to listen to it on the Jolida. It sounded like a blob of undifferentiated sound between the two speakers. Yes, I could tell it was music, but could not listen to it. I thought, surely this is a poor recording, and even remastered as it is, they could not improve it much. I was wrong. On the torii it sounded just right and I could tell one saxophone from another and from the trumpet, the bass from the drum etc and I was not even missing the stereophony because the 'soundstage' was coherent even in mono. I call that a huge improvement.
The zen kit was doing that well too. However I prefered the Jolida to the zen kit on a number of recordings, as the Zen was lacking bass, especially on the hungry not so sensitive Triangles, and the Jolida sounded big, good for Karkwa, Bashung etc, rock bands.
The torii sounds right with mostly anything, although I wish it had Jolida's BIG sound sometimes.
Can you tell it's raining and I have nothing else to do today? Smiley
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Re: Mini Torii SE Amplifier
Reply #35 - 04/18/11 at 00:55:32
 
No need to apologize for anything at all, Raduschka.  You hear what you hear and your experience is what it is.  I have had the Jolida 801A for three year now.  It is the one with the bias pots on the bottom; really, the most ridiculous design!  As you know, to bias it, one must turn it over, and since there are three transformers, I use a coffee can as the fourth leg.  Each time I need to bias this thing, I think to myself it is time to get a new amp.

Regarding the big sound of the Jolida, remember you are comparing a 70 watt tube amp to a 4 watt tube amp.  At a certain point , no matter how good the amp might be, in my view, 4 watts isn't going to cut it in every situation.  (Now donning flame suit).  

I was going to have Bill Baker mod mine but one delay led to another and by the time I was ready, Bill stopped doing mods on it so he could concentrate on his own amps.  So, maybe it is not such a bad thing that he stopped doing mods.  It makes for a compelling reason to consider either the Mini Torii or the Zen Torii Mk III.  

The only thing stopping me on the Mini Torii is the idea of re-tubing the amp.  I like the idea of tube rolling; this amp takes that idea to an extreme and for me, might be a distraction.  

Anyway, thank for describing the differences you are hearing between the two amps.  Next time, I turn over that
!@#$ Jolida to bias it, maybe the next thing I do after that is order a Decware amp.  
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Re: Mini Torii SE Amplifier
Reply #36 - 04/18/11 at 03:19:46
 
I can't think of a worse idea than placing bias pots on the bottom of a huge and heavy amplifier. It has to be running on top of everything, connected to the speakers and everything.....
Do you have the budget for the zen torii mk3? If I hadn't wasted my money on a zen kit and a bunch of useless stuff I would have gotten one of those I guess, but I always think the next purchase will sound better, it is time for me to enjoy what I have, especially since I now have a really great amp!!!!!
I don't really see how the tube rolling would put you off, plus I am sure the mk3 is just as sensitive to it as the mini torii. If you can hear the subtle differences between tubes it means that the rest of the amp is that good, that transparent. With the Jolida I would switch tubes and cables and hear no difference, not such a good sign.
I was hesitant to build my own speakers since I was afraid I would have to play forever with the damping, afraid I would get it wrong and always wonder if my speakers could sound better if made by a professional. None of that has subsisted, I know now from experience how damping affects sound and feel responsible for part of my sound, as if I had cooked myself a good meal rather than have my grandmother expertly but secretly prepare it for me.
Tube rolling could get expensive and out of hand, but if done responsively it is a source of guiltless pleasure. I am discovering it now, because my set up allows it.
http://www.flickr.com/photos/61617415@N02/5629720211/lightbox/
http://www.flickr.com/photos/61617415@N02/5631091661/lightbox/

http://www.flickr.com/photos/61617415@N02/5631779780/lightbox/

http://www.flickr.com/photos/61617415@N02/5631196141/lightbox/

http://www.flickr.com/photos/61617415@N02/5642238854/lightbox/

http://www.flickr.com/photos/61617415@N02/5642238072/lightbox/
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« Last Edit: 04/22/11 at 02:41:14 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #37 - 04/20/11 at 01:14:16
 
Not to hijack the thread any further so one final comment about the Jolida 801A.  I have the manual and confirmed the model through Jolida using the serial # before I bought it.  The model I have is the 801A with the bias pots on the bottom. I read somewhere the B version is the an updated 801A after Jolida wised up and put the pots on the top.  I'll respond to your PM a bit later.

With respect to tube-rolling, I am not saying it wouldn't be fun.  For me, with certain time constraints and all the possible configurations to try, well, it would be a distraction because I can be impatient.  

The Decware forums have gotten more interesting lately with new members posting experiences and some of the old regulars chiming in with their own experiences or helpful suggestions and new product introductions.  

Back to our regularly scheduled programming.
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Re: Mini Torii SE Amplifier
Reply #38 - 04/22/11 at 03:23:16
 

_MG_3238 par raduschka, sur Flickr


mini t par raduschka, sur Flickr


_MG_3031 par raduschka, sur Flickr


_MG_3233 par raduschka, sur Flickr

_MG_3039 par raduschka, sur Flickr


_MG_3229 par raduschka, sur Flickr


Capture par raduschka, sur Flickr
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« Last Edit: 04/22/11 at 14:36:56 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #39 - 04/27/11 at 23:10:10
 
Hello,
does anyone have any experience with Cifte Mazda 12au7 tubes in the Mini torii? I am using them now and they sound particularly detailed, with remarkably extended highs. I keep comparing them to Mullard 12at7 and they both sound great. I think I prefer the Cifte for their capability to reveal detail in the music and the Mullard for their overall tone. Can anyone please tell me how many hours it takes to break in an input tube? That is, to make sure I am listening to the tube at its 100%.
Thank you
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Re: Mini Torii SE Amplifier
Reply #40 - 04/28/11 at 00:25:28
 
Somebody commented favorably on them a while ago. They should be broken in after a few hours.
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Re: Mini Torii SE Amplifier
Reply #41 - 04/28/11 at 00:31:36
 
Thank you!
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Re: Mini Torii SE Amplifier
Reply #42 - 04/28/11 at 01:48:11
 
Genalex - Gold Lion 6V6GT / CV511 reissue (80$ for the pair)
sound really uninvolving compared directly with the stock JJ that were on the Mini Torii (and which cost around 25$ the pair here in Canada). The JJ have punch and a sweet midrange, the Genalex have nothing special to them.
They sound nasial and unnatural in my system.
My experience.
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« Last Edit: 05/06/11 at 00:11:51 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #43 - 04/28/11 at 02:00:13
 
..
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« Last Edit: 05/06/11 at 00:10:48 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #44 - 05/02/11 at 21:19:29
 
Achtung achtung all of you,
I have received in the mail my 2 pairs of Duende Criatura tube rings. Yes, in my setup, and I do not see why it would be particularly prone to vibrations of any kind, they make a huge difference. And one desirable difference that is. I had time to relisten to a murky sounding cd I tried to listen to yesterday. With the rings in place on the 12at7 and the 6v6 I realized that there was nothing wrong with the recording (Sephardic Romances on Naxos). Timbre, soundstage, they turned out to be absolutely alright, whereas yesterday the voices sounded nasial, the strings had a weird ring to them and it was impossible to tell where everything was placed. Another visible difference, I can now turn up the volume and the sound remains palpably clean.
Not inexpensive at 100$ for 2 pairs, but very interesting per se, apparently sturdy and indestructible, backed up by 15 years of existence.
In my experience they live up to their official claims of cleaning up the soundstage and tightening the bottom end. I haven't yet tried to listen with only 1 pair in place, some say that there is a danger of overdamping the tubes and thus making the amp sound less musical. The mechanics of that elude me and I do not like to believe in things that I don't understand, but I will keep you posted if my experience confirms any of that.
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Re: Mini Torii SE Amplifier
Reply #45 - 05/02/11 at 22:48:10
 
Raduschka,

Thanks for sharing your impressions. I believe that these could work very well because they are similar in important ways to the Herbie's Audio Lab "Tube Dampers" that I use in my system. They really "focus" the sound. Pricing for Herbie's best is similar as well.
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« Last Edit: 05/02/11 at 22:48:36 by Lon »  

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Re: Mini Torii SE Amplifier
Reply #46 - 05/05/11 at 18:06:49
 
Hello everyone,

I own an isolation transformer and it has a rather thin power cord, while the rest of my system is fueled through thick gauge power cables. It seems a little odd to to see two thick power cables drawing current through a thin cheap cable from the wall outlet.
Do you think I should fit the transformer with a thick gauge power cable and quality plug?
My knowledge of isolation transformers is so limited that I depend on a kind opinion from you.
Thank you
Raduschka
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« Last Edit: 05/05/11 at 18:12:18 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #47 - 05/08/11 at 18:01:50
 
is there a quick fix for radio interference? I have had for the past 2 weeks an intermittent whistling noise in the background.
What have I done now to deserve this...:-)

Thick cable on the Tripp Lite: much better bottom end.

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Re: Mini Torii SE Amplifier
Reply #48 - 05/08/11 at 20:08:08
 
I traced back the interference problem to my new nos philips blackplate 6x4 (rats...). Is there a way to keep using them without the high pitched noise? Is there a way to shield them?
Thank you
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Re: Mini Torii SE Amplifier
Reply #49 - 05/21/11 at 15:15:46
 
As I have described in other places on this forum,  I have been searching for the best combo of tubes in the MT for my system.  Recently, I placed a pair E80CC input tubes along with a pair of Mazda 6x4 rectifiers in the MT and I am hearing much better synergy in my system.  When I have used the Mazdas in the past in other equipment, I was impressed with the bass response and these tubes are improving the bass of the MT.  I had forgotten that I had the E80CC tubes, a sort of a super 12AU7.  

Now, it is time to look at some other 6V6 power tubes to squeeze out some additional tone.  Any recommendations?
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Re: Mini Torii SE Amplifier
Reply #50 - 05/21/11 at 15:51:14
 
Hi,
I settled on a pair of NOS NEC 6v6 (from thetubestore.com) and NOS mullard 12au7. The NEC have an audible edge over other 6v6 I have tried, the bass is rounder, the mids are more credible. I have tried a pair of RCA blackplate greyglass and took them out immediately, they produced no bass at all. I don't know if smth was wrong with them or the combination of tubes... I haven't tried 6x4s yet, except for a pair of nos bplate Philips (tubestore too) and they did make everything sound ...creamier I guess, a little darker but more interesting.
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Re: Mini Torii SE Amplifier
Reply #51 - 05/21/11 at 16:38:17
 
..forgot to mention that the philips  6x4 blackplate are unusable in my Mini torii ( and perhaps in all of them???) because they whistle like there is no tomorrow...
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Re: Mini Torii SE Amplifier
Reply #52 - 05/26/11 at 01:30:48
 
I have just added a PS Duet Power conditioner to the audiofamily. In conjunction with my modified tripp-lite it has allowed the musical experience to reach new heights. The level of detail and coherence is now almost indecent and so is the level of enjoyment... I am slowly losing my fitness, as I sit at work and sit at home!
After this evening's listening session I felt like doing two things (three actually but I can only talk about two of them): one, move over to THIS chair and write to you all about what a 200$ PS Duet can do and say thanks to Lon, whose suggestion about getting the Duet lead directly to a purchase thereof from partXconnection.
two, become religious for a second so that i can thank a power higher than Steve Deckert, of which he is only a messenger. (and then return to my beloved atheism and try to explain the miracle of what I hear without invoking the supernatural).
Hugs and kisses
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Re: Mini Torii SE Amplifier
Reply #53 - 05/26/11 at 01:47:23
 
Alright, glad you had a positive experience with the Duet. I tried doing without mine but didn't like it at all when it was removed, you're right about the refinement of the sound.

Keep on enjoyin' the sounds my friend!
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Re: Mini Torii SE Amplifier
Reply #54 - 06/05/11 at 02:13:56
 
...I installed a hospital grade outlet in my living room, as the one I was using was remarkably loose. upon inspection, the wires coming out of the wall were completely darkened by decades of unattended existence so I brought their coppery shine back  with a piece of sand paper. Yes, now I have even better sound coming out of my system, easily audible in the bass zone, but the whole sound is more lifelike. Sting-dream of the Blue Turtles MSFL happened to be the cd in the player. Moon over Bourbon street-well, he is right there, on top of the bass and there is a saxophone in the back. "You can't say that"-the two notes on the bass, they feel like a real bass guitar being played  now and the percussion is life like. etc etc
I bought a red leviton hospital grade outlet from
frwoodworking on Ebay, for 7$ + 2$ shipping or so. Not the best, but it works for now.
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=230625178913&ssPageName=STRK:M...
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Re: fantastic diy pure silver interconnects
Reply #55 - 06/13/11 at 19:31:03
 
to all Mini Torii owners and everyone interested in fantastic diy interconnects: http://www.audioasylum.com/cgi/m.mpl?forum=cables&n=152650&highlight=

And vh audio: http://www.venhaus1.com/diysilverinterconnects.html

For 150$ I now have fantastic sound. My system already had a Phd, now it has finished 10 years of post doctoral studies ans is working for the UN on humanitarian missions and writing best selling books on its favourite topics. Maybe one day it will  be an accomplished painter.

These interconnects have allegedly been preferred to no-costs-barred interconnects. Although I never tested such expensive objects I can tell you that they sound way better than what I had and that the guy selling them answers all emails and is really sweet to deal with. I urge you to try making them, it is easy!!!
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Re: Mini Torii SE Amplifier
Reply #56 - 06/25/11 at 18:10:22
 
http://www.msnbc.msn.com/id/43532031/ns/technology_and_science-innovation

is anyone aware of this? Will it affect the sound? Should I move back to Europe? Smiley
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Re: Mini Torii SE Amplifier
Reply #57 - 06/25/11 at 18:31:59
 
I read that in this morning's paper and wondered the same thing. That is just what we need, someone Effin' areound with the cycles of our electricity. I can only guess on what kind of havoc this will play with our systems. I wonder how it will effect industry, I know that all of my machines are very picky about what you feed them, the drives go wacko if they don't get what they need.
I was just offered a job in China, maybe I should consider it more seriously.
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Re: Mini Torii SE Amplifier
Reply #58 - 06/25/11 at 21:19:45
 
I also wonder what effect this will have. Changes in cheap timekeeping like microwave ovens, don't worry me too much, though the aggravation will be annoying. I do wonder what frequency variability will do to line noise, if anything, and the quality of sound. Will have to pay attention to what happens on the Monster AVS-2000 and the PS Audio Power Plant when this happens.
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Decware: Ultra | Torii MKIII [2] | SE84ZS | Taboo MkIII Sources: Synology 1812+ | Baetis Revolution | PWD DAC MKII | Lumin Network Player | Mytek 192 | Oppo 105 DSP: DEQX Mate | Emotiva Outputs: ERR [6] + Servo Subs | LCD-2 & other cans
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Re: Mini Torii SE Amplifier
Reply #59 - 10/01/11 at 21:05:40
 
hello everyone!

Can anyone please spell out for me the differences between the 4 types of gas voltage regulators in regard to their impact on the sound? I own 3 of the 4 types, with the 4th in the mail, due on upcoming Monday. I have noticed that the 0d3 takes away from the bass but makes it tighter and quicker. What I would like to know is wether it also makes the soundstage appear less deep and focused, as I can't seem to decide by myself. I also have the feeling it makes the midrange less screamy and overall it feels like the amp handles the speakers better, as if it had more power.
The 0a3 seems to give bloated and slow bass notes, but I am afraid everything else is somewhat more elegant, although the percussion does seem a little lifeless in comparisaon to the 0d3 presentation.
I keep reading that the 0c3 offers the best regulation of the 4 types. I wish I understood what that means, especially in practical terms, for my mini torii and listening experience.
The 0c3 arrive, as I said, on Monday.
I suppose whatever those gas regulators do, I can find a middle path with the 0b3 and the 0c3. Hopefullt the best of 2 worlds, if there are such 2 worlds. I haven't heard a world of difference though.
Thank you for any input!
yours
Raduschka
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Re: Mini Torii SE Amplifier
Reply #60 - 12/07/11 at 02:38:32
 
hello everyone, I am about to buy a diy audio note DAC  (kit 2.1 B) and would like to know if its higher output voltage (2.5 rms) is compatible with the Mini Torii, I remember reading somewhere that the amp would actually benefit from higher input voltages, but I wouldn't sleep tight if I didn't double check. Thank you in advance
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Re: Mini Torii SE Amplifier
Reply #61 - 12/07/11 at 12:31:47
 
The MINI TORII can do more with lower voltages than a TABOO can. I think you will do fine with a 2.5 volt output in the MINI
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Re: Mini Torii SE Amplifier
Reply #62 - 12/07/11 at 12:54:02
 
thank you!
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Re: Mini Torii SE Amplifier
Reply #63 - 12/22/11 at 23:02:13
 
good Lord, I soldered together an AudioNote 2.1b D.A.C. and it is breaking in right now, sounding incredibly different from my tubed CD player that I am now using as a transport only. I tried to use a pair of EZ81 rectifiers (through adapters) instead of the native 6x4 with very poor results... I only have 1 pair of RFT (nos) EZ81 tubes, I wonder if the poor results are due to these particular tubes... By poor I mean limited depth of soundstage basically, yuck, it all sounded like a very detailed brickwall in front of me!!! Could the EZ81  be an intrinsically bad idea on a mini torii????? Rivieraranch?
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Re: Mini Torii SE Amplifier
Reply #64 - 12/23/11 at 01:47:36
 
I am sorry to hear about the problems you have had using the EZ81 rectifier.

I bought a pair of NOS RFT rectifiers from Jim McShane and the adapters you mention. I never compared the 6X4 with the EZ81 because I used my EZ81's and adapters exclusively with 6Y6G power tubes.

The 6Y6 proved too much for the 6X4 rectifier, which is why I tried  the EZ81 in the first place. When I spoke to Steve Deckert about the problems I was having with the 6X4 he conceded that the 6X4 is the "weak link" in that amp. However, the 6X4 was chosen because it sounded very good.

For me, trying the EZ81 was more of an experiment. I am using 6L6WGTB power tubes and 6X4W rectifiers right now. I might swap in the EZ81 to make a comparison when using the 6L6 family. I doubt there is anything wrong with the RFT rectifiers.

You should also consider that you could use a 9-pin 6V4 (EZ80) rectifier as well. Since you already bought the adapters you could try that alternative.

Steve also mentioned that the currently produced MINI TORII is now using the 9-pin EZ81 rectifier. I doubt it could be bad.      
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Re: Mini Torii SE Amplifier
Reply #65 - 12/23/11 at 01:54:37
 
yes, I had the same line of thought, i doubt it could be bad since Steve is using it... Could it be that he modified the circuit somehow to accommodate the ez81??   The 6x4 sounds significantly better, not just different... Hmmm... I am puzzled. The adapters are great. I wonder about the other type of rectifier...

Steve meant weak link in terms of availability I suppose?? Or current?
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Re: Mini Torii SE Amplifier
Reply #66 - 12/23/11 at 10:34:54
 
Weak link in the sense that if the power tubes are biased real high (since the unit is self-biasing) they stress the rectifier and could blow it. If your 6X4's are glowing too bright then you are headed for trouble.

You should ask Steve if there is any change to the internals with the move from the 6X4 to the EZ81.
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Re: Mini Torii SE Amplifier
Reply #67 - 02/29/12 at 00:09:07
 
Hello!  I've been having a little trouble logging in, but a call to Decware and very nice chat with Steve himself helped take of things.  As of the last post on the Mini Torii, the one my dear wife ordered for me was wrapped up in holiday ribbons and paper -- and I hadn't a clue about!  This amp is among the very first I haven't built myself (what a treat!), and Marie ( said dear wife) mentioned again how genuinely kind, friendly, and helpful everyone at Decware was to her.  You see, I've been looking at Decware amps from the beginning, and we almost purchased one of the original kits so many years go it's kind of scary.  And even then the absolute customer oriented nature of this small company was obvious -- only helpful, with no pressure of any kind.  I have built a large number of amps since that time, from OTL, to different varieties of 2a3,300b and so forth....ac filaments, dc filaments, etc., etc., including amplifiers from Moth Audio, which we bought as a chassis and bunch of parts, Bottlehead, Welborne Labs, and others.  And I love all those amps; they each have something to offer, but not equally in the same situation.

And then comes along a diminutive but not tiny, and very light weight amp called the Mini Torii. I was and am thrilled with it.  With our Lowthers and klipschhorns, and La scalas, it is without a doubt the best amp we have in terms of power supply rejection.  Hooked up to La Scalas, the sense of clarity, presence and surprising bass weight from such a small amplifier was completely not in keeping with its size and weight.  

The input jacks are not isolated from the chassis with shouldered washers, suggesting perhaps a ground plane.  But I am intrigued to get in to see exactly the kind of ground scheme is used and to discover what makes this marvelous little amp as quiet as it is with Lowther horns, which as many of you know can be ruthless in that respect.

And so, this first post has gone on long enough.  Thanks to Decware and Steve for being so helpful to a wife who wanted to surprise her husband with a genuine Decware valve amp for Christmas.  I haven't tube rolled in years but have some old Philco radios I worked on with output tubes that will work in this amp!  So for now... erik2a3
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Have fun!
erik
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Re: Mini Torii SE Amplifier
Reply #68 - 02/29/12 at 00:20:09
 
yay erik2a3, glad to have some news from a new mini T owner! As for me, today I regranished the insides of my diy audio note cabinets and decided to experiment with squares of wool attached to the rays of the speaker basket (to soften sound reflections from the backside of the paper cone). Amazing results!!!! My girlfriend graced me with a listen in and she cried a little because I played the song that always makes her cry apparently... Of all songs it is Roger Waters' 3rd track on Amused to Death Smiley I take it she doesn't quite understand the lyrics, as she is French speaking, how else could one cry to that Smiley I'll have to check with her.
My mini is also dead quiet, amazingly so with sensitive speakers, but it has developed an intermittent noise on one channel. No big deal yet, I dread having to ship it back to Steve, since it weighs half a ton. Regards
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Re: Mini Torii SE Amplifier
Reply #69 - 02/29/12 at 00:44:41
 
Congrats Erik! Welcome to the forum!
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Re: Mini Torii SE Amplifier
Reply #70 - 02/29/12 at 00:54:05
 
Maybe you will become Erik 6V6?
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Re: Mini Torii SE Amplifier
Reply #71 - 02/29/12 at 01:21:37
 
Hi erik2a3!  I'm interested in your early experiences with the Mini, as I ordered mine mid January (along with the DM945 speakers), and I still have to wait a while for its delivery.  Evidently, having previous technical exposure, you have the opportunity to judge its performance relative to the other amps at your disposal.  So, keep the comments coming.  Congrats!
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Re: Mini Torii SE Amplifier
Reply #72 - 02/29/12 at 23:53:07
 
Thanks for the warm welcome!

Raduschka: you know, Roger Waters and other former associates have written songs that are downright emotional regardless of the lyrics.  Melodies rather than accompanying words seem to stick with most, and others, such as some of Brian Eno's 'Ambient Music' can be pretty intense in that respect.  She sounds like a nice and sensitive girl!

Hi, Lon and Riviereraranch!  erik6v6?  Not so bad I guess!  I used to listen to a pair of very vintage pp 6v6 monoblocks that sounded ok, yet not even close to the single-lunged Mini-Torii.  2A3s are just kind of like old friends, I guess, and what I use in my headphone amp.

Greetings Fireblade - well, I suspect I sort of anticipated a question along the lines of what you asked, but....whew....that one could take some time to answer, and would involve a bunch of revisiting amps and doing the best I could to conduct a reiable comparison between them.  I do have some technical background, and am able to explain some of what I hear relative to circuit topology, but must confess I've learned that a technical background and design experience don't always enable one to difinitively state in a universal sort of way what is better or worse.  This hobby is just very much too subjective for that, and it seems to me the best anyone can do is draw conclusions about personal preferences that very likely may not by shared by others.   As crazy as it sounds, because it probably is crazy -- is that I have amplifiers I prefer for different reasons and different kinds of music.  And I tend to go through listening phases where for some weeks I might really be into classical Baroque, and other times prefer Bill Bruford, King Crimson, Genesis, Yes, No, ( ok...bad joke!) or Miles Davis, Eberhard Weber or Segovia.  And Audioslave, Tool, Perect Circle, Dream Theater -- much harder stuff that to sound 'right' may be better with a harder hitting amp with characteristics that heavy a tight and controlled bass response.

Although the Mini-Torii is still new, I can say that it has a certain 'rightness' in terms of tone and evidently even-handed frequency response that, while at first seemed mildly rolled off on the top (think I have that one figured out) prompted me to share with the people at Lowther America that I think it's probably the best amp I have used with my beloved Lowther PM2As.  I have other amps that sound really good with them, but leave me thinking about a few things I may want to change in terms of perhaps mild reductions in feedback, interstage coupling capacitor selection (absolutely NOT necessarily more expensive -- I've learned a thing or two about that).  The Mini-Torri was so quiet I literally thought I had forgotten to connect the speakers.  With Lowthers, that's saying something.

Feel free to email about this if you like -- I worry I write too much sometimes.  
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Re: Mini Torii SE Amplifier
Reply #73 - 03/01/12 at 01:00:04
 
Fireblade:  Reading what I wrote above, I suspect I haven't helped answer your question.  Something I discovered with the Min-Torri, but have had hints of it in the past, is that one not need spend several hundred dollars on a pair of output tubes in order to get not only satisfactory, but amazing sound reproduction.  singe-ended triodes, and triode amps in general have a sort of cult-like following (not unlike lots of tubes, actually....we seem to gather in tribes!), but I have very, very expensive 2A3s that do not better, in their associated circuits, the Mini-Torri's 6V6.   Many of you might want avert your eyes, but I recently bought a small T-class amp that with some of the heavy mentioned above sounds pretty good.  What it makes me think about, though, particularly after talking briefly with Steve, is....well, the Mini-Torri's bigger, more powerful sibling.  That will be a bit down the road, because I am really enjoying the Mini-T!  I've got some old but still good output tubes to try that is going to be fun.
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Re: Mini Torii SE Amplifier
Reply #74 - 03/01/12 at 13:36:35
 
Thanks for sharing those thoughts, erik2A3, I really enjoyed them.  In did not have a specific question, just an invitation to share your initial impressions, from the point of view of someone more versed than myself in this field and sharing the same amp.

I concur with your valid observation that everything, in the end, is personal and subjective.  Nevertheless, some of your statements already shed some light in my own conceptual image about the Mini Torii's strengths and weaknesses.

For someone looking for a do-it-all amp, like me, and willing to use it within a modest listening space, I chose the Mini-Torii (also suggested to me by Steve), because of it's versatility.  Your mentioning of the cult about SETs in general, is very true, to the point that have made me forget sometimes the reasons why I selected the Mini in the first place.

For the kinds of music I prefer, mostly classic be-bop jazz and classical (both orchestral and chamber music), I thought the Mini Torii could meet those requirements, if constrained within the physical dimensions of a small listening room.

Having pre-outs should also help with my subwoofer, a requirement for jazz listening and smaller (yet highly sensitive) speakers.  Beam tubes like the 6V6 are better at bass, too.  Best of both worlds also, as you have pointed out, the 6V6's being competitive with the best triode tubes out there.

Don't worry about writing too much, as for the interested parties in this forum, it is never enough!  Enjoy your Mini and keep us posted on new insights about it ...   Smiley


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« Last Edit: 03/01/12 at 13:41:33 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #75 - 03/02/12 at 00:01:49
 
Indeed, the transformer-derived line level output of the Mini-Torii is the best I have found in terms of integrating a subwoofer.  The gain and impedance relationsip just fits the two very well.

I honestly know but a small fraction aout this than many, Fireblade.  I've learned a bit from focused research and reading, and what I have learned about myself in the process is that, the more I get into it the more I realize how much I don't know!  I have books about audio desgin that were written such a very long time ago, and find the extense of understanding back then really sort of mind boggling impressive.  So much of what is being done today has mostly been done before, yet the Mini-Torii, which was inspired by an old instrument amp, has traits incorporated by an insightful designer.

Nice bike, by the way!
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Re: Mini Torii SE Amplifier
Reply #76 - 03/02/12 at 01:53:11
 
That's just fine, erik2A3, but you know more than I do about this, so I'm learning from you as I've from many knowledgeable people in this forum.  It's reassuring to confirm by your observations my expectations about the pre-outs for the SUB.

I also admire Steve's work, an uncommon talent indeed.  His articles, business model and the loyalty he has induced from the members of this forum convinced me to take the plunge into this peculiar and very special market niche.

Thanks for the compliments on my bike.  The one you saw earlier and this one (in my avatar) are just file photos.  Mine is a Pearl White 2009 model (exactly as the one in this avatar), but with several important mods and upgrades.  As you can see, I have these two passions Cheesy.

Take care ...

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« Last Edit: 03/02/12 at 01:59:18 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #77 - 03/11/12 at 23:06:39
 
And so, the little Torii only gets better, teaching a very expensive pair of 2A3s just how good a single-ended amp can sound.  I had called and talked to Steve about a very minor rolling off of high frequency information, and while talking with him I suddenly remembered -- a bit to my chagrin -- the HF attenuator.  And this was indeed the issue.  A flip of the switch brought back amazingly clear and clean highs. Just a really superb amp!

We share the same 2nd passion!  I had an R6 years ago, sold for something more my age and speed, Cagiva Gran Canyon, and then sold that and saved for my dream, which has a boxer twin Cheesy
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Re: Mini Torii SE Amplifier
Reply #78 - 03/12/12 at 01:57:40
 
I'm glad there were no real issues with the Mini Torii.  I'm ready to try mine as soon as it gets here!  My new USB/DAC (HRT MS II+) is sounding cool, better than I thought.  I can't wait.

Seems we share similar toys: The bike I had before this one was a 2007 candy apple YZF R1, great machine.  Two bikes before that one, and a mount I had for 5 years, was the 1997 BMW R1200C (boxer twin).  Reliable and very good handling, considering its weight and size.  Quite comfortable too.

After trying to catch up with some superbikes on the road, one day I decided I wanted that new thrill.  I hesitantly sold that BMW and bought a used (2001) CBR929RR, and never looked back.

Age is a concern for me too, as I'm not as eager to take risks as I used to.  So my current bike has seen less of my wild riding than the previous ones.  I may eventually give up on superbikes and get back to standards, but not anytime soon!  Ride safe!

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Re: Mini Torii SE Amplifier
Reply #79 - 03/13/12 at 14:16:47
 
You will love the Mini Torii.  In a short mount of time, it has distinguished itself very positively against much more expensive, not to mention much heavier amplifiers.  The first watt of this little gem is one heck of a civilized and refined first watt.  Kind of shatters the notion that the key to good sound in a valve amp is directly related to the size of its output transformers.

An R1? Fast!  Scary fast!  Be Safe!
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Re: Mini Torii SE Amplifier
Reply #80 - 03/13/12 at 18:19:38
 
I hear you, and I'm so glad you appreciate it in that context of tough competition.  That's why I asked you to report on impressions.  Your experience and familiarity with similar amps is relevant.

The '09 CBR1000RR runs rings around my ex-R1.  Lighter, more available torque, better handling, faster acceleration.  Ignition module and Power Commander III help also, along with the full Akrapovic exhaust.  It's the best one I've ever had!

Enjoy your M-T!
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Re: Mini Torii SE Amplifier
Reply #81 - 04/01/12 at 22:11:33
 
I know many of you have done some tube rolling on the Mini T.  I woke up from a short Sunday afternoon nap (a rare luxury!), happened to glance over at my c. 1930s Philco Radio, and remembered it uses a pair of 6F6 outputs.  Thirty seconds later they were installed in the M. Torii.  Well, I have to say that it is really fine sounding!  I find the 6F6 sharper and very clean and clear, where, while still excellent, the 6V6 somewhat warmer, softer.  Next went in two of the four 6L6s that are residing in an amp I bought to rebuild into a dedicated stereo amplifier -- a 1950s vintage Baldwin organ amp.  Such an awesome and flexible little amplifier!  I do prefer the 6L6 or 6F6 types, particularly the latter.  So, this was just to share.
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Re: Mini Torii SE Amplifier
Reply #82 - 04/02/12 at 17:37:18
 
Thanks for the tip.  I will be trying a couple combinations once my amp is broken-in.  There are several options in my short list.  We'll consider your suggestion.
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Re: Mini Torii SE Amplifier
Reply #83 - 04/03/12 at 01:21:14
 
Some don't care for the 6F6 type, Fireblade.  It is an older, just very neat as a vintage application, and the pair I happened to try had, for lack of a better way to describe it, a sort of purity of tone and clarity, at lower volumes, than did the particular 6V6s used before.  Also tried both 12au7 and the 12at7, and find the 12au7 not only quieter (I very much dislike background noise) but more delicate and resolving -- this with several CDs of classical guitar music.  For higher volumes and/or heavier music genres with more bass laden passages, a combination of 12at7 and perhaps 6l6 outputs might be really outstanding.  Have fun!
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Re: Mini Torii SE Amplifier
Reply #84 - 04/03/12 at 02:53:41
 
Interesting.  I would try to settle on a unique driver (i.e., 12aU7), and identify two different pairs of output tubes that would work best for each of those two scenarios, respectively.  I would only switch output tubes depending on the type of music (scenario) involved in each session.

I'm not sure this approach is attainable, but it would be ideal to keep gain in control.  I know from literature (never have had any practical experience rolling tubes) that the 6L6's, as you pointed out, are 'bigger' sounding beam tetrodes than, for example, 6V6's.

For the finer material, 6F6's may be just the ticket, based on your findings.  I would hate to try-and-err without a plan, so I'm trying to rationalize the approach.  Does this make any sense?

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Re: Mini Torii SE Amplifier
Reply #85 - 04/03/12 at 11:36:30
 
Fireblade

If there is one thing I have learned about all of this is that there is not right or wrong or better or worse that can be applied universally.  This includes not only input and output tubesin the Mini Torii, but every aspect of listening to music at home.  It is fine for us to share our (highly subjective) impressions of components and elements of those components.  What is simply impossible is to apply or impose those impressions on one another as ultimate 'truths' in all instances.  Our hearing and processing of sound is just to individualized than that, regardless of the fact that the same anatomical structures are used.  Our response and opinions differ as much as preferences of food, beverage, art, or anything else.   The only mistake you can makemis try everything you might be interested in as far as valves for this amp, and based on that, perhaps select what seems to work the best in most instances.  I have a great aversion for statements and declarations I have found on forums where one individual will criticize the choice or tastes of someone else simply because thay aren't aligned with his or her own.

So play with your amp and enjoy the search!  It's ability to be personalized is one of its virtues -- and by all means continue to have fun in the process! Smiley
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Re: Mini Torii SE Amplifier
Reply #86 - 04/03/12 at 16:50:15
 
"The only mistake you can makemis try everything you might be interested in as far as valves for this amp, and based on that, perhaps select what seems to work the best in most instances"

Why would this be a mistake?  I mean, we all know this is highly subjective.  But out of the significant number of possible alternatives, one has to try at least what seems to work for other people and maybe increase the probabilities of shortening the selection path.  It is certainly better than trying this on a blind draw.

On the general subject, though, I agree with you. Thanks.

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Re: Mini Torii SE Amplifier
Reply #87 - 04/03/12 at 20:39:44
 
FB,

Our amps will be brand new and I plan to run it stock until it settles in.
I will go real slow rolling tubes until then. O.K. I'll likely plug in a pair of 350B, after 100 hours or so.

"The only mistake you can makemis try everything you might be interested in as far as valves for this amp, and based on that, perhaps select what seems to work the best in most instances"

The above can be a mistake because you will go broke and crazy...not necessarily in that order. Don't ask me how I know that. Wink

Les
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« Last Edit: 04/03/12 at 21:57:25 by Les Lammers »  
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Re: Mini Torii SE Amplifier
Reply #88 - 04/03/12 at 23:38:37
 
Let me correct my incomplete first thing in the morning response: certainly I meant that the only mistake you can make is to NOT try,within reason, any ideas in the way of suitable tubes for this amplifier.  What I or anyone one else likes can be a start, but your ears are your ears and of course you must try for yourself.  Some find the old 6F6 soft compared to the 6v6 or 6l6, and may even question its use at all.  This is an example of the sort of imposing of ideas and opinions that I mentioned above.

Fireblade: your interest in getting the best possible you can from the Mini Torii is obvious and a very positive thing!  It's this kind of enthusiasm that is encouraging!
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« Last Edit: 04/03/12 at 23:46:01 by erik2a3 »  

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Re: Mini Torii SE Amplifier
Reply #89 - 04/04/12 at 01:51:49
 
Mini Torii chassis has beem removed from wooden bass, and headphone jack will be installed tomorrow.  I must credit Decware for a very nicely wired little amp, with very clean lead dress and classisc ground buss.  textbook soldering, and quite a bit better than what I've seen from, surprisingly, well known companies.  Truly nicely done, and that makes me happy.  I've always used carbon comp resistors in grid stop positions, but the metal films off the wiper of the volume controls are doing just dandy.

In case some of you might ne interested: I know of an extremely quiet, tube rectified and regulated amplifier that is DEAD quiet with my Grado phones.  Wow.  I have a couple of others that are quiet, but the noise floor on this thing is just really amazingly low.  The gain seems perfect for the headphones.

I'm referring of course to the Mini Torii, and comparing it to an otherwise very highly regarded and well reviewed single ended amp, the Moth Audio si 2a3, which I still very, very much like to use from time to time with Klipshorns and Lowthers.  I'm sure some of you had the phone jack installed, but I didn't so will get that done tomorrow.

Thanks for doing such a nice wiring job on our Mini Torii!!! At times in the past I have cringed at work I have seen inside tube amps, despite the super snazzy looking exterior.
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Re: Mini Torii SE Amplifier
Reply #90 - 04/04/12 at 02:39:54
 
Thanks for clearing that up, Erik.  Now it makes sense to me.  I think the key issue is finding tube rolling advice from experienced people sharing your same amp and somewhat similar setup, and whom you trust their ears/tastes, as a starting point.  The only way to ID them, is trying their suggestions once.

I appreciate the fact that you find the Mini Torii very quiet and that you are positively surprised by the quality of its craftsmanship.  All this is very reassuring for us.

BTW, presumably the Taboo is an even better option for headphone listening, especially if you intent this as the main application for the amp.  On the other hand, having an amp with so much flexibility as the M-T is very convenient.

Florida Boy, I think we're in for an amazing music sound adventure.  Let's keep the information flowing throughout the preliminary break-in and fine-tunning process ahead.  8-)
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« Last Edit: 04/04/12 at 02:48:49 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #91 - 04/04/12 at 11:04:42
 
Fireblade

Sure, apologies for any confusion there. It was early and I was in a rush to get to school to get some things done before students arrived.  

I was just curious about the headphone application, and temporarily made an external jack plus ground off the speaker outputs.  Not sure if this will be its primary function in life, but it worked just dandy!  The amp internally is also very tweakable for those so inclined because, despite its multi-stage regulation and various switching functions, the circuit is fairly straight forward and wiring layout easy to follow.  One could even get into the sometimes kind of neurotic coupling capacitor rolling (like tube rolling but involves more work) and the values of capacitance are small.  That keeps costs down.  There are also a couple cathode resistor bypass capacitor positions I'm looking at, but, as I said mich earlier on, performance is just great as itmis right now.  Have a good day!
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« Last Edit: 04/04/12 at 11:14:10 by erik2a3 »  

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Re: Mini Torii SE Amplifier
Reply #92 - 04/04/12 at 15:26:28
 
Erik,

No apologies required.  Thanks for the inputs.  It must feel great to have the skills to be able to tweak the amplifier yourself, to your own tastes.  Take care now ...
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« Last Edit: 04/04/12 at 15:27:50 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #93 - 04/04/12 at 23:30:06
 
Hi, Fireblade

Thanks for being an understanding sort of person.  It can be useful to tweak.....and sometimes something of a curse....and I have decided to leave as is except for the volume control addition.  The Mini Torii is already well balanced, quiet, and very musical.  I'll go find another amp or two I have that are actually broken and fix those!  Got some 6Y6 tubes today, but they have a bit of a higher filement current requirement.  Thus my interest in knowing the current availability withnthe stock M.T. Power transformer.  Tske care, erik
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Re: Mini Torii SE Amplifier
Reply #94 - 04/05/12 at 11:25:55
 
Erik6Y6:

BE CAREFUL with those bottles! If your MINI TORII has the 6x4 rectifier, and the 6Y6's bias too high the rectifier could go. Look for an older thread on my experiences with this. The 6CA4 EZ81 rectifier can handle any 6Y6.
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Re: Mini Torii SE Amplifier
Reply #95 - 04/05/12 at 22:02:30
 
Fireblade,

Here is how I scout tubes that I am not familiar with. Pick a tube, like RCA 6L6G, go to the Audio Asylum tube forum and search. You will find a lot of relevent info and some BS aka baseless opinion. Try it.

Les
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Re: Mini Torii SE Amplifier
Reply #96 - 04/05/12 at 22:52:01
 
Thanks for the heads up, Rivieraranch! I'll be sure to check into this before trying things out.  I appreciate it!

Edit: the main concern I had for the 6y6 had to do with its higher filament current.  That's what will cause some heat if if the power transformer is not up to the task.  To this end I had posted a request on this site for specs for the filament widning current rating.  I may to to reconfirm this, but if I remember right, the 6y6 filaments pull nearly three times the current of the of the 6v6.  If I like the 6y6 that much more, there may be space under the chassis to install dedicated filament transformers that are good for about 3A.  If plate voltage in the mini torii is siginificantly high with the 6y6, other circuit adjustments in the power supply can be made for it.
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Re: Mini Torii SE Amplifier
Reply #97 - 04/05/12 at 23:03:53
 
Thanks for the tip, Les.  I'll check it out. Smiley
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Re: Mini Torii SE Amplifier
Reply #98 - 04/06/12 at 00:00:21
 
My mini torii sounds so realistic and transparent that now I can listen to music from another room Smiley I neurotically exchanged the plate caps for a pair of CuTf Vcaps and the resistors in the signal path for some  Shinkoh 2-watters, the stock fuse for a fancy one and bypassed the source selector. All this because I have had an annoying hiss in one of the channels and didn't feel like spraying the resistors with freeze-spray. Instead I am replacing the components one by one until it goes away.
It is getting crowded in there.
150 hours burn in and things sound impressively more transparent, to a point where I discover new elements on old timers such as Pink Floyd albums, which I know by heart.
Even my dear mother thought I was insane to try to improve upon my super amp from the States, but here it is, never having sounded better and me ever so curious to listen to my collection again and hear things for the first time. And ever so eager to get rid of that hiss...
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Re: Mini Torii SE Amplifier
Reply #99 - 04/06/12 at 00:43:46
 
and since I am at it, I would like to ask you all if you know of a way to install a headphone jack inside the amp without any additional switches in the signal path? A shunt type that would present a fake load to the output transformers and be switched on by inserting the headphones, or by a switch... I don't know enough electronics at this point to figure it out by myself. Any idea will be appreciated!
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Re: Mini Torii SE Amplifier
Reply #100 - 04/06/12 at 01:31:33
 
I have an even more burning question: my current attenuators are already too loud at the 1st step!! Can you please suggest a resistance value that i should be looking at that might allow several steps before I get to the comfortable volume zone? What should I be looking for? Any quality  mono attenuators out there? Thank you very much
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Re: Mini Torii SE Amplifier
Reply #101 - 04/06/12 at 02:48:44
 
Erik6Y6:

By the way, when you have the 6Y6 tubes in the amp it runs hot as hell. The chassis and everything is a lot hotter to the touch as well.
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Re: Mini Torii SE Amplifier
Reply #102 - 04/06/12 at 03:15:49
 
I apologize for interrupting the ongoing discussion.
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Re: Mini Torii SE Amplifier
Reply #103 - 04/06/12 at 03:59:47
 
Ah Rad, as the great Monte Negran genius Nero Wolfe would say, "PFUI."

:)

Good to see you posting sir.
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Re: Mini Torii SE Amplifier
Reply #104 - 04/06/12 at 04:03:33
 
why would he spy for the Austrian government??:-)
glad you are still alive
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Re: Mini Torii SE Amplifier
Reply #105 - 04/06/12 at 20:56:03
 
Rivierafarm

Yah, gotcha.  You mentioned the heat before.  As mentioned, I can add a dedicated filament transformer good for 3A, as well as drop the B+ on the plate if needed for the 6y6.  Heavy current pull by filaments is probably a main source of heat.  All of these changes are exceedingly simple for me to do.  Thanks again for the heads up.  No worries.
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Re: Mini Torii SE Amplifier
Reply #106 - 04/06/12 at 22:00:16
 
Radushka wrote:

"I have an even more burning question: my current attenuators are already too loud at the 1st step!! Can you please suggest a resistance value that i should be looking at that might allow several steps before I get to the comfortable volume zone? What should I be looking for? Any quality  mono attenuators out there? Thank you very much "

Are you using a 12AT7?
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Re: Mini Torii SE Amplifier
Reply #107 - 04/06/12 at 22:15:16
 
hi, I am using 12au7 as input tubes. The volume pots are 100k. I am wondering if I can change that value in order to get what I want or is there an easier way...
I found these, they come in 50k, 100k and 250k if I recall correctly:
http://www.partsconnexion.com/product20925.html
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Re: Mini Torii SE Amplifier
Reply #108 - 04/06/12 at 23:09:36
 
Radu

A good way to solve this problem is not so much to use a lower value potentiometer -- that may help, but probably mildly, at least that has been my experience in the past.

Parts Express also sells in-line attenuators that essentially offers series resistance, knocking the sginal down by say 6dB or 12dB depending on the one you need for appropriate use of your volume pots.  These really work quite well. As a mattermof fact, I think I have a pair of 6dB attenuators you can have for the cost of your address Smiley.  They look like long RCA plugs (2 inches or so), and can be installed on the amp or preamp/source end -- in this case, probably the source since the jacks on the M T are on the top of the chassis.  Alternatively, you can use a fixed 100k ohm resistor in-line with the signal going into the inputs to the volume control.  If memory serves me right, 100k, which I believe is the value of the pots on the MT, will bring the signal down by about 6dBs or so.  Happy to help if you have questions.  The mini torii is an awesome amp, but some of these modifications can't be solved without mild, rather simple, changes to the circuit.  None of these change the overall character of the amplifier, so the work at Decware and essential voicing of the amplifier remains complete.
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Re: Mini Torii SE Amplifier
Reply #109 - 04/07/12 at 00:17:15
 
thank you all!!!! I think that would be a good way to go Erik2a3, but I cannot use the external attenuators for lack of space. My interconnects are hardwired into the dac and they are the exact length to the top-mounting rca on the mini torii (it was an error), so I cannot add absolutely anything btw them and the rca. Very sweet of you to propose mailing them to me!!!
So I am thinking the following: rather than install extra resistors in the signal path, isn't it possible to reduce the output of the DAC by swapping some already exising resistors in the analog board? Heere is a schematic of one DAC channel, I am not proficient enough to think any further, but perhaps you can have a look and suggest a different value for any of those resistors? Thanks
http://www.flickr.com/photos/71648043@N02/6905930510/

ps: w35 is where it goes out to the amp, just in case it helps to know...
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« Last Edit: 04/07/12 at 00:18:32 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #110 - 04/07/12 at 00:35:29
 
Hmmmm...

Instead of changing the output voltage of your DAC, as an initial experiment to see how the attenuators work you could use the inline attenuator as the means by which you add perhaps another meter length of IC to give you both some extra flexibility in terms of placement of components, but more importantly, get the added benefit of lowering the gain into the amplifier.  Do you understand?  What you would do is first disconnect the IC going into the amp.  2: plug the ends of that same IC into the female end of the in-line attenuator.  3: then use a a small, female to female RCA adaptor(which are used for adding one length of interconnect to another) on the opposite ond of the attenuator. 4: now take the remaining interconnect -- perhaps only a foot or so is really needed -- and connect one end into the remaining female end of the adaptor/attenuator combination, and the other end into the Mini Torii.  This sounds involved, butnit is very simple and should work fine.   If the connectors are of decent quality it will work exactly right.  In effect, you are just adding some length to your IC.  This would be much easier than changing your DAC outputs, which would actually achieve the exact same thing as the added resistor I mentioned inside the mini torii, only the resistance is further downstream.  Do you see?
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Re: Mini Torii SE Amplifier
Reply #111 - 04/07/12 at 01:03:50
 
Eric,

Is the volume control 'hair trigger' with your speakers? I have a 2.5 volt DAC and for got to ask Steve about this being a possible issue.
Been there before.

Les
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Re: Mini Torii SE Amplifier
Reply #112 - 04/07/12 at 01:27:26
 
I see how adding a resistor right before the volume pots or right at the exit of the dac is one and the same thing. I am convinced that that kind of attenuating method would do exactly what it promises to do. I was just wondering if perhaps there is a more direct way of lowering the dac's output voltage. I asked Brian of AudioNote too. My first step will probably be to buy a pair of 48 step mono stepped attenuators, either 100k or lower (although I do not know yet what the implications of going lower are). If I find that, again, in a few steps I reach max listening levels, I will proceed with the other kind of attenuation. Thank you, you have been most helpful!!!
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Re: Mini Torii SE Amplifier
Reply #113 - 04/07/12 at 01:35:44
 
Florida boy

No.  But they are pretty sensitive with headphones.  I'm using it with a squeezebox right now for headphone use.  I had the squeezebox output fixed, full volume, but altered the settings so that I could adjust the SB output to about middle range.  Leaving it in that position, I get good control using the pots on the Mini Torii.  But, even with the La scalas I had reasonable volume control without having the slightest rotation blow the walls down.   Just not sure of this particular situation.  It may be that changing the volume controls to something like 10k ohm might help.  If one can get away with that value ptentiometer, there are extensive tests I've read about in journals that indicate improved hogh frequency response with say 10k ohm potentiometers vs those in the range of 100k, 250k, .5meg, etc.  (I'm still struggling with typing on this ipad!). Hope you all are enjoying a nice Good Friday!
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Re: Mini Torii SE Amplifier
Reply #114 - 04/07/12 at 01:48:24
 
Radu

I know it seems sort of counter intuitive, but the lower the value of control, the LESS sensitive the control is.  Higher values like 100k or 250K present a higher impedance to the incoming signal, which means things will be more sensitive (louder) with the higher value.  The other issue that comes into play with the lower impedance, such as would be the case with a 10k control, involves the relationship between the source output impedance and the new, lower (10k) input impedance of the mini torii, which, depending on the rotation of the VC (volume control), will likely be even lower.  So, if you have a high source impedance going into an overly low amplifier input impedance, there is a chance of poor coupling between the two.  The usual result is reduced high frequency response, and overall poor performance.   Can you tell me what the output impedance spec pf the DAC is?  Also: is there a chance you can change the hard wired IC back into a situation with panel mount jacks?  That would really give you some more flexibility.

BTW: the general output/input impedance ratio is considered good if in the range of 1 to 10.  So, for example, if the output impedance of your DAC is 1kohms, the minmum suitable input impedance (established by either a fixed grid leak resistor or variable volume control) would be 10k.
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Re: Mini Torii SE Amplifier
Reply #115 - 04/07/12 at 01:51:59
 
I am trying to find out right now!
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Re: Mini Torii SE Amplifier
Reply #116 - 04/07/12 at 01:53:15
 
it is 1.3k!
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Re: Mini Torii SE Amplifier
Reply #117 - 04/07/12 at 01:56:07
 
so I should be safe with a 20k stepped attenuator, with possibly better highs but steeper taper slopes?

smeeper staple flops

yes, good night everybody and happy Good Friday, you have been good to me and I thank you once more
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« Last Edit: 04/07/12 at 01:57:01 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #118 - 04/07/12 at 03:40:44
 
Florida Boy,

I understand the M-T comes stock with a 12aU7 (low-gain) driver, which should help with the highish DAC output voltage (my USB/DAC is also 2.25 V).  

According to specs, a 12aT7 will have the M-T reach full power on 1 Volt input (clipping after half a dial of volume pot at 2.0 V input), so since the 12aU7 is significantly lower gain, the full power should be on the 2+ V mark (i.e., clipping with volume pot well beyond half dial).  

This ought to allow some leeway with volume control before max power with DAC outputs above the 2.0 V mark, like in our case.

Of course, this is just my interpretation of the specs.  Let's see if someone more versed in this matters can confirm it.  

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« Last Edit: 04/07/12 at 03:46:05 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #119 - 04/07/12 at 03:59:22
 
my dac puts out 2.5V (rms?) . I use 12au7 as input tubes and by the 2nd click out of 9 total clicks on the volume pots I start feeling uncomfortable because it is too loud for the neighbours, although it still sounds great. Any position btw the clicks is hard to dial in and maintain.
....
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Re: Mini Torii SE Amplifier
Reply #120 - 04/07/12 at 04:23:12
 
It may get relatively loud soon (depending on your speakers' sensitivity and room size), but the question is how far from the clipping point it really is.  This does not resolve the volume sensitivity you are already experiencing at 2.5V input, I suppose, but I was hoping the 12aU7 would help keep things in control.  

I know the 12aU7 is 20 Mu's only, compared to 60 Mu's for the 12aT7 (12aX7 is 100 Mu's).  The higher the Mu rating, the higher the gain imparted to the circuit.  There may be other variables involved in this that I'm not aware of, though.

However volume sensitive the M-T is at an input of 2.5 V, it would be even worse with the 12aT7, other things being equal.  Yet, people here report successful results with 12aT7 in place, so there must be some other variables in play?
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Re: Mini Torii SE Amplifier
Reply #121 - 04/07/12 at 04:27:26
 
I am a total amateur, Erik will know much more about this, but in my MT there is a 2k7 resistor btw the volume pot and the input tube. Can that play a role in this?
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Re: Mini Torii SE Amplifier
Reply #122 - 04/07/12 at 04:44:13
 
It may, but this design is supposed to work as it was built, accommodating a range of output and driver tubes to skew its performance to meet particular conditions and tastes, by replacing specific tubes and not altering the circuit's basic design.

So, there must be something in the step volume attenuator circuit (if yours is a mod over the original volume pot), that is somehow short-circuiting the gradual attenuation into a bigger step (jump) than expected.

Don't take my opinion as technical, as I'm an amateur like you.  But I would try to see where in the dial the amp is actually clipping, and you'll realize whether there is a problem or is just a relative loudness perception issue.

Let's see if Erik or Kevin can give us some light here.  

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Re: Mini Torii SE Amplifier
Reply #123 - 04/07/12 at 04:48:22
 
original pots here. I had the same volume issue with my CD player. My speakers are self made AudioNirvana 10 inchers, I think 98 db sensitivity, but I can't confirm that.

anyhow today I finally replaced the resistor that was causing a hiss and crackle phenomenon in the right channel, so I feel like I deserve the Nobel price for electronics Smiley
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Re: Mini Torii SE Amplifier
Reply #124 - 04/07/12 at 04:53:27
 
Good for you!  If you have the standard volume pots, then I'm at a loss.  Can you try to find the clipping point in that dial (without having to be expelled from the neighbourhood)?  It may well be your speakers' ultra sensitivity (anything above 96 dB is ultra sensitive for this amp).
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« Last Edit: 04/07/12 at 04:57:27 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #125 - 04/07/12 at 04:58:18
 
they should be thankful for a Nobel price in the neighbourhood.
I cannot really go there volume wise though...

but second click, that would be around 9 o,clock, off the top of my head, is already too loud, yet clear and manageable. i don't think I ever went past the 2nd click. I still do not understand clearly what I must do, but I am convinced that a high quality step attenuator will give the amp a new life. I just don't know yet if they should be 10k, 50k, Dact, Khozmo, Goldsmth, yadda
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Re: Mini Torii SE Amplifier
Reply #126 - 04/07/12 at 05:05:05
 
A preamp or ZStage may help you ride the gain also ... Control the max volume through a second device, allowing for better dynamics.  Just a thought.  Or a DAC with built-in output control.
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Re: Mini Torii SE Amplifier
Reply #127 - 04/07/12 at 05:10:06
 
I'll see how it goes with an attenuator. If the first steps are any use I can live with a steep gain. If my favourite volumem level is somewhere between those clicks I am going to have to install a resistor somewhere before the atts or lower the output of the dac somehow, maybe directly in its circuit. I am waiting for Brian of AudioNote to illuminate me on that plan. I am off to bed now! Sleep tight!
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Re: Mini Torii SE Amplifier
Reply #128 - 04/07/12 at 11:49:37
 
"I am a total amateur, Erik will know much more about this, but in my MT there is a 2k7 resistor btw the volume pot and the input tube. Can that play a role in this? "

Radushka, I would call Decware. There should be an easy way to reduce the gain. Parts Connexion has a good selection of attenuators.
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Re: Mini Torii SE Amplifier
Reply #129 - 04/07/12 at 12:10:04
 
Good morning, raduscha

That 2.7k resistor on the input to them12AU7 is in a position thatmis sometimes referred to as a 'grid stop' or grid suppressor resistor.  These are also sometimes used in the output stage. Common values are in the range of say 1k to 10k ohms or so.  There usual function is totally unrelated to gain issues.  They are are used to help sort of 'calm' a circuit that may otherwise exhibit high frequency parasitic oscillation.  Almost all of my amps use them.  My Moth Audio si2a3, which we purchsed in the form of a chassis, schematic, and box of parts, uses just such a resistor on the input stage.  In this case it's a common carbon comp resistor where the one on the mini torii is a metal film.

In any event, the output impedance of your DAC is a little high-ish, but not extraordinarily so.  The 100k of the mini torii should be well within a suitable range for it in terms of impedance matching.  Fireblade is right, however, that the higher gain 12At7 can effect this to an extent, but you aren't using that tube.  An impedance buffer could be used, I suppose, and you might try it for curiosity, but you may or may not be interested in adding additional circuitry.

Truly, the common cure for this situation are the in-line attenuators I mentioned above.  I am very picky about what I hear in terms of wanting good detail with requisite bite to the music, and I did not find the attenuators to roll off high frequencie, to cause noise, or anything else.  They just bumped the signal down a bit.  

Another part of this we haven't talked about yet has to do with the sensitivity of your speakers.  Sensitivity and efficiency are not the same thing thing, which is why an input voltage spec in the range of a bit over two volts (sensitivity) is listed in conjunction with the efficiency rating (dBs with 1 watt at a meter).   Based on your description, your speakers likely have a very simple, low order crossover, such as a 6dB per octave slope, which in a two way system consists of only two elements: a capacitor in the high pass to the tweeter and an inductor in the low pass to the woofer/mid bass driver.  If this is the case, a low order network like this presents a low insertion loss to the signal from the amplifier, which means that things will get loud more quickly than they would with a more complex network.  More sensitive still, are single driver, crossoverless systems like Lowthers, Fostex, etc.  the MT sounds beautiful with our 15 ohm crossoverless lowthers, but the mini torii is a better match for the equally efficient Klipsch La Scalas -- an extremely fine match, actually, and I spent a long time listening to this combination yesterday.  I also tried a 12at7 as the driver, and in our second listening space it proved to offer some real excitement.  The 12au7 is far better for headphones, however....

Please let us know how things progress!
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Re: Mini Torii SE Amplifier
Reply #130 - 04/07/12 at 12:13:24
 
Forgot to mention those grid stoppers are also very often used to help provide immunity against RFI, and I first used them because we live in an area plagued by nearby high power transmission antennas.  I found an even better cure for this problem, though....
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Re: Mini Torii SE Amplifier
Reply #131 - 04/07/12 at 12:36:13
 
Erik,

Thanks for your input on the Klipsch. I had the same issue Radushka has when I was driving La Scalas with 300B's and a pre amp that had too much gain. I believe his speakers are single drivers with no crossover in a ported enclosure.

Les


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Re: Mini Torii SE Amplifier
Reply #132 - 04/07/12 at 13:16:22
 
Florida Boy -- the Audio Nirvana ....yes, you're right.  So often, one can get by without the additional gain of a preamp for that very reason.  Many high sensitivity, high impedance amps only need a pretty small drive signal less than a volt, to get them up and running, in fact where the output of the source is more than enough to push the amp into clipping.  I've paddled in the same boat as both of you, and actually have one foot in it now with our Lowther horns being driven by 300 B monoblocks.  Here's my situation: I use both systems side by side but for different music genres.  The Lowthers horns, which are hugely efficient and of course sans crossovers, are being driven by the 300Bs, which in tuen have a solid state preamp in front of them.  This preamp was an unbuilt NOS Dynaco PAT 4 kit I came across and HAD to have.  It's a preamp that I have always liked, despite its vintage, and had the opportunity to put together myself in the way I prefer.  I has tone controls and a treble roll-ff switch that I use in very small amounts, and give music a very nice sharpness and fast transients where and when needed. But, the gain is a little on the high and sensitive side but acceptable.  I may throw in those attenuators I mentioned to Raduscha, but have just been enjoying the sound so much I haven't bothered.  I also have a valve preamp consisten of a quad of 6sn7s I made probably ten years ago (scary!), thatnis good, but doesn't posses the sharpness and detail I like-- probably 'cause my ears are older and I can't hear as good as I used to! Shocked
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Re: Mini Torii SE Amplifier
Reply #133 - 04/07/12 at 13:31:39
 
Raduscha

Something else: intalling a 10k linear (rather than log or audio taper) pot (trim pot) on the output of your DAC, therby allowing you to fine tune the gain into the amp.  This is not unlike what Fireblade mentioned, but withput the extra circuitry and power supply elements of an impedance buffer stage.  I'm sure you know this already but the 'Z' in Z-box is a designation of impedance.  As in: output Z  is shorthand way of referring to output impedance.

Edit: I hadn't read through all of this before responding, but Firblade did mention the output control on the DAC or a preamp.  Both excellent ideas!  I think he has great thoughts on this.  The amplifier dual pots could be used to balance and adjust the iput level into the mini torii and use the volume control on preamp as the general purpose control.  Just leave the M. Torii pots set.
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Re: Mini Torii SE Amplifier
Reply #134 - 04/07/12 at 13:42:40
 
Ok -- lastly!  Sorry, ideas keep coming to me.  Some vintage amps had potentiometers on the input into the amp so that high level and low level source signals could be matched more closely.  On the MT there are two additional holes near the binding posts that could be used for input gain pots.  These would attenuate the signal before going to the selector switches and volume control.  Again, 10k might be a good value to try, however the hole are for mini switch shafts, and might need to be drilled if a larger pot were to be used.  Just an additional thought.........
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Re: Mini Torii SE Amplifier
Reply #135 - 04/07/12 at 14:08:26
 
Erik,

No xover to suck power and a 2.5v source is the issue. I think a call to
Decware will be Radushka's best bet. I think I will be OK using  12AU7's. I am having my Mini built with a stereo volume pot and think I will purchase a very good quality one and send it to Deware to be installed. I am leaning towards using Takman carbon resistors and Audio Note copper foil caps and may send them to Decware with the attenuator. I have plenty of time to decide.

Happy Easter all,

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Re: Mini Torii SE Amplifier
Reply #136 - 04/07/12 at 14:30:47
 
Jesus and Mary, I managed to sleep well despite the whole obsession with trim pots and atts! I see you've been thinking while I was asleep Smiley  
Yes, my AudioNirvanas are fullrange inside ported cabinets, as Fireblade pointed out, so no crossovers there.
From what I understand, if the output Z of my dac is 1.3k I should be looking at a 20k or maybe 50k attenuator? I take it seriously when you say, Erik, that lower impedance pots have a better impact on high frequency reproduction. I read an article yesterday about how important a good quality volume pot is in a preamp and so I am all worked up about getting a dact or smth similar. I am willing to try those attenuators you mentioned, if you 'promise' they won't confront my purist mentality Smiley I can pm you my address and perhaps send you smth good from Montreal in return, maybe smth to eat??
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Re: Mini Torii SE Amplifier
Reply #137 - 04/07/12 at 19:27:33
 
I'm afraid now I may confront the same problem: My speakers are the DM945's (no cross-over, 94dB) and my USB/DAC is a highish 2.25V output.  What I don't understand, is how come people using even the 12aT7's as input drivers and with sensitive speakers, still find the gain manageable.  

Theoretically, the M-T is supposed to accommodate for all these variations in driver and output tubes for sources ranging from 1 to 2 V, without issues.  For example, with a 12aT7 and sensitive speakers (94-98 dB), the volume pot may reach full power at mid-dial using the stock 6V6 output tubes for typical sources @ 2 V.

Following this reasoning, someone using 12aU7 drivers in these same conditions ought to be able to go at least half dial before clipping, with source signals beyond the 2.0 V mark.  The driver's lower gain should compensate for the extra input voltage, making the setup gain profile still manageable.

Evidently, there are exceptions to this, as has been described earlier.  Anyone has a clue?  Should we prepare ourselves in advance to cope with this potential problem?  How? We'd be hard pressed to find good DACs with lower output signals than the typical 2 V.  Is the M-T condemned to be used either with an iPOD or other low output source and/or the application of a high quality volume step attenuator mod?

I'm just trying to see if I may confront this problem when my gear arrives, and to prepare myself in advance with a potential counter-measure.  Thanks for your inputs.
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Re: Mini Torii SE Amplifier
Reply #138 - 04/07/12 at 19:32:55
 
Fireblade,
remember that in my case we are dealing with appartment friendly levels, so I don't have a clue where my amp clips. My initial problem was with how little leeway I have between 0 and the first click and how hard it is to make the pot stay in place btw clicks. So in my case the second click is already too loud.
BTW I think my AudioNirvanas inside cabinets are 94 db too, but I better check.
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Re: Mini Torii SE Amplifier
Reply #139 - 04/07/12 at 19:34:14
 
Floridaboy

What I mentioned about this are the most usual ways of dealing with excessive gain....which I have dealt with over twenty years and from designing and building some of my own amps.  But doubtless you are right that Decware knows more about there products than anyone!  We are  just sharing ideas, which in my view makes for beneficial discussion.

He could also even use a variable L pad on his driver, selected to match the impedance of the same... But yuk, it would be better to take care of it at the line level, if by no other way than by putting a preamp between DAC and amp.
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Re: Mini Torii SE Amplifier
Reply #140 - 04/07/12 at 19:37:11
 
...no way am I buying a preamp Smiley
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Re: Mini Torii SE Amplifier
Reply #141 - 04/07/12 at 19:38:26
 
I am still caught btw attenuator models... Khozmo, DACT, Goldpoint....
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Re: Mini Torii SE Amplifier
Reply #142 - 04/07/12 at 19:41:35
 
I have precisely 3.6 mm under the cover of the Mini T to install 2 mono atts. Ladder type.
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Re: Mini Torii SE Amplifier
Reply #143 - 04/07/12 at 19:55:21
 
maybe i could get one of those diy goldpoint attenuators and choose my own resistor values so that I have a lot of room to adjust the volume between 7 and 12 o,clock? They come at about 150$ for 2xmono (shipping included). Am I deluded?
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Re: Mini Torii SE Amplifier
Reply #144 - 04/07/12 at 19:56:48
 
Radushka,

Even if I have less volume-level listening restrictions, having an extra-sensitive volume pod is not ideal.  I thought I would have at least half a dial to find my optimal volume level.  This may not be the case if the gain is so high, that jumping from one of the initial clicks to the next, misses the intended volume target altogether.

I have not heard about this problem before (with the M-T), so I guess in most cases is still manageable.  But then again, my DAC is 2.25 V. Sad
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Re: Mini Torii SE Amplifier
Reply #145 - 04/07/12 at 20:02:01
 
yes, I agree it is a problem, even in my case, I was just suddenly afraid I had exaggerated it, but I hadn't. So seriously, if I am not completely off the mark I will buy 2 mono atts from Goldpoint's ebay site and colonize them with my own choice of fancy resistors from PartsConnexion. And I don't even need high volumes!!!! When I move into a huge house with passive solar design, inspired by Mies von der Rohe, I will take them out and add new resistors.
Plus the Goldpoints fit nicely under the hood.
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Re: Mini Torii SE Amplifier
Reply #146 - 04/07/12 at 20:43:59
 
What is your source...what is feeding the DAC?
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Re: Mini Torii SE Amplifier
Reply #147 - 04/07/12 at 20:46:30
 
a Cayin cd t15 tubed output cd player. used as a transport only of course
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Re: Mini Torii SE Amplifier
Reply #148 - 04/07/12 at 21:08:42
 
Does it have analog outputs?
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Re: Mini Torii SE Amplifier
Reply #149 - 04/07/12 at 21:10:47
 
sure
I had the same issue with those (2 v I think) But I can't remember if it was slightly better. I could try later on, I gotta go out, eat some sushi with my girlfriend.
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Re: Mini Torii SE Amplifier
Reply #150 - 04/07/12 at 21:42:10
 
I've been assuming all along that the volume sensitivity grows linearly with the analog input signal voltage (other things being equal), but it may well be an exponential function.  Meaning, anything beyond 2.0 V may increase loudness at ever increasing rates.  

If the original design is optimized for the [sub 1 V to 2 V max] target, we may be at  the steepest stage of that function after the 2 V threshold.  This may explain the inordinate sensitivity with sources even moderately higher than the 2 V mark.  If so, Radushka is in a greater predicament than I, just because of that 0.25 V difference.

This may also explain the apparent indifference of using driver tubes with different gains, so long as that source output does not go beyond the 2.0 V max.

If this reasoning is correct, I would expect those using 12aT7 and highly sensitive speakers and not experiencing such loudness sensitivity (an apparent paradox), most probably have sources strictly under, or at, the 2.0 V mark.

Anybody cares to comment?
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« Last Edit: 04/07/12 at 21:48:13 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #151 - 04/07/12 at 21:47:57
 
wouldn't that be a function of the pot design too? Or predominantly? I emailed 'alpha inc.' a hi res photo of the pots and am waiting for them to send me a spec list.
We didn't go eat sushi after all, I am home obsessing about Dale Vishey 1% resistors and Goldpoint atts that will solve all my problems. ALL my problems Smiley
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Re: Mini Torii SE Amplifier
Reply #152 - 04/07/12 at 21:51:56
 
Not if that same pot design is replicated in most M-T's around.  The paradox would not occur and everybody (not only the ones with highish DAC output voltage) would have experienced the same ultra sensitivity issues.

Don't get obsessed, just enjoy the challenge  ;)
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Re: Mini Torii SE Amplifier
Reply #153 - 04/07/12 at 21:53:55
 
Sushi with girl friend is better thsn sny sttnuator you'll ever find.  I just tried an experiment: digital output from CDP into Lexicon DSP, and Lexicon into mini torii.  Mini torii volume control up about 3/4 way.  Using the Lexicon this way, which has it's own volume control in the preamp, works quite wondefully well.  Rmember, that if the MT were a power amp, it would used a fixed, 100k ohm resistor on the grid of the first half of the input stage to ground.  This equates to the volume controls being turned all the way up, which provides the greatest resistance relative to ground.

So, even if your source had a 5 volt output, if you have a transparent linestage, which the Lexicon very much is, ypu can adjust the gain between the volume control of the preamp and dual pots of the Mini Torii -- if you don't mind the extra electronics between the two.  I don't, it works extremely well.
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Re: Mini Torii SE Amplifier
Reply #154 - 04/07/12 at 21:58:12
 
that would mean that I replace the pots with high quality 100k resitors and use the mini t as a power amp? WHile adjusting the volume from the output of the DAC?

DO you think I could solve the issue by building my custom atts?
I am a little hypoglycemic, that is why my brain is a little slow on this issue.  I'll be in the kitchen helping my gf cook.
'helping'
hah
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Re: Mini Torii SE Amplifier
Reply #155 - 04/07/12 at 22:03:43
 
you may have noticed I am hell-bent on replacing the stock pots.
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Re: Mini Torii SE Amplifier
Reply #156 - 04/07/12 at 22:04:52
 
My brain is a little slow, period!  I had sushi for lunch today -- I love it!!

Sure, I actully toyed with the idea of using it as a straight ahead power amp.  You take out the volume controls and replace them with a fixed resistor.  This may or may not solve the problem, though....

With a preamp in the mix (I know you don't like the idea), you can sort pf balance things out between both components.
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Re: Mini Torii SE Amplifier
Reply #157 - 04/07/12 at 22:15:16
 
I like the idea, but I think good volume pots will work wonders in term of sound quality and I don't have any more money to invest in expensive parts (after I buy the atts and their resistors that is:-)) .
I still do not understand what determines an att's nominal resistance.  Erik said a ratio of 1 to 10 btw output Z and pot resistance was optimal. The dac's output z being 1.3, my att should be 20k let us say (13k sounds odd). How do I achieve that on a custom att??? I will look it up on the Goldpoint site, they have lists about just that.
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Re: Mini Torii SE Amplifier
Reply #158 - 04/07/12 at 22:20:31
 
http://www.flickr.com/photos/71648043@N02/6908641606/

there is a 'resistor designator' bottom left, going to gnd, I suppose that one determines the resistance of the att when it is wide open? (maximum volume I presume)
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Re: Mini Torii SE Amplifier
Reply #159 - 04/07/12 at 22:27:20
 
As I mentioned yesterday, a definite solution is to 'ride the gain' through the use of a second component, be it a preamp, a ZStage or an output controllable DAC.  Yet, it should not be the case, as the M-T design is supposed to be robust enough to handle the popular range of market sources' (CD players, DACs) output specs.  Besides, this would be against the 'purist' approach!

Although I've been contemplating the addition of a ZStage to the M-T myself, just to be able to get the benefits or 'riding the gain' (better dynamics, for example), I had planned to wait until the gear is broken-in before making any additions or adjustments.

The other straightforward solution is to replace our DACs with something under the 2.0 V mark output.  But I would hate to do that just now.  I think I'll wait for my Mini Torii and DM945's to arrive and we'll see.  

In the case of Radushka, a fine, highly-stepped attenuator design may be just the ticket (i.e., an attenuator with double the number of ticks per arc-sweep).  Sonic degradation is the only possible risk here (not because of the concept, but in terms of design and build quality).  

Just my thoughts.
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« Last Edit: 04/07/12 at 22:35:10 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #160 - 04/07/12 at 22:32:00
 
the atts I am looking at are the series, not the ladder type, but they have a very good reputation, especially when paired with non-noisy resistors. I could make a non linear att, with the most used volume levels right after the zero position, so I can dial in directly :
1st click: day level volume,
2nd click : evening
3rd click: late night
linear from 4th click on
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Re: Mini Torii SE Amplifier
Reply #161 - 04/07/12 at 22:33:19
 
I guess I think this isn't an attenuator issue.  I have used very expensive stepped attenuators years ago, and found the only real improvement had to do with the better channel to channel tracking in the stereo voume control.  Sound-wise it was perhaps marginally better than the cheap carbon comp control.  I've been using Alps blue volume controls almost exclusively, which are a good balance in terms of cost and performance.

I could be completely wrong.  Maybe a nice Goldpoint, which I think are very but also very expensive controls would make all thendifference in the world.....my gut feeling is that it won't change the sensitivity problem appreciably.
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Re: Mini Torii SE Amplifier
Reply #162 - 04/07/12 at 22:33:53
 
Fireblade, do you think an att would degrade the sound more than a preamp? A preamp has its own volume pot. I am worried now, what do you mean by sonic degradation?
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Re: Mini Torii SE Amplifier
Reply #163 - 04/07/12 at 22:35:34
 
so Erik, from your experience you think a 200$ att will not bring about a marked improvement over the stock volume pots?
regardless of the input sensitivity issue. Just sound wise
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Re: Mini Torii SE Amplifier
Reply #164 - 04/07/12 at 22:48:21
 
Not at all.  In both cases it's going to depend on the quality of their design, materials, build, etc.  Although, what Erik is pointing out may suggest the attenuator won't really solve the sensitivity issue.  

I'm not qualified to suggest anything other than trying the attenuator should at least allow you that in-between volume target you're missing now.  Assuming there's no sonic degradation and the cost is less than an additional component, you'll be better off in purists terms and presumably able to dial-in the optimum volume level.

If, on the other hand, you want to take advantage of the situation and tap the benefits of riding the gain, there's always the second-component alternative, if you care to invest in it.
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Re: Mini Torii SE Amplifier
Reply #165 - 04/07/12 at 22:56:33
 
GOLDPOINT MONAURAL MINI-V STEPPED ATTENUATOR (2) 10K, 20K, 25K, 50K or 100K

I still do not understand which resistnce value works best in my set up. The dac puts out 2.5v, and output Z is 1.3K. How do I match up the dac with the mini t here? 20k to replace the stock 100k??
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Re: Mini Torii SE Amplifier
Reply #166 - 04/07/12 at 23:04:54
 
Radu: I'm not really saying it wouldn't be worth it.  Like caps and other passive parts, the end result is probably kind of subjective.  Fireblade stated this as I also see it -- that the type of attenuator may not be the main culprit.  With two basic types of controls, those being log taper and linear, the really nice attenuators approximate the log or audio taper with values of resistance that match the way we perceive incremental changes in volume, which is how the cheap pots in the torii, mini, also do.  Fwiw: I am honestly not in the least inclined to change them.  But this just me, only becausenI have learned after truly ridiculous amounts of comparing caps, resistors, transformers, volume controls, etc., thatmthe best one in a particular circuit is quite truly not necessarily the most expensive one.  I have had $60 capacitor in one hand, and a $0.25 one in the other, and after comparing both both decided to use the cheaper. But the opposite has also been the case.  My point is that despite the lower costnof some of the parts on this amp, they work very well, and for that I am happy!  I think a really good sounding preamp is what would do the trick in your case...but I might be completely off base.  I say this because I just tried it and it can work as well or better than not having one in the signal chain.
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Re: Mini Torii SE Amplifier
Reply #167 - 04/07/12 at 23:10:10
 
I would encourage you to ask Steve this question, directly.  That phone call is worth it, given all the uncertainties involved, and may shed some light on this issue, once and for all.  Sometimes, defining the right question is tantamount to solving the problem optimally, especially if you can talk to The Man.
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Re: Mini Torii SE Amplifier
Reply #168 - 04/07/12 at 23:12:10
 
I am listening carefully Erik! I am still afraid that the Vcaps might have made it sound too forward compared to the original caps, so I can see in practice how expensive parts do not automatically improve things. At this point, even though a preamp might be the best solution, I don't want (can't rather, who doesn't want? Smiley)
to invest in a more than decent preamp. That is why I am focusing on the volume pots, not as much to solve the gain issue as to make sure such an important part as the volume pot gets a fair treatment.
Yeah, I should call Steve. I am just a bit intimidated...Plus I installed Vcaps in the man's amp. I am ashamed Smiley
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Re: Mini Torii SE Amplifier
Reply #169 - 04/07/12 at 23:20:35
 
I wrote to Steve. He usually answers. Otherwise I will call. I would still like to know what attenuator value I should be looking at.
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Re: Mini Torii SE Amplifier
Reply #170 - 04/07/12 at 23:43:29
 
I wasn't aware you had VCaps (Teflon or Copper-Teflon?).  This may be the 'X' variable that may explain the odd behavior and the apparent paradox.  Which means the M-T design is robust, after all, in handling moderate deviations in DAC output voltages beyond the 2.0 V mark (with the original Caps in place).  So, Erik was right in discarding a possible volume pot issue.

You may still need that stepped attenuator now to compensate for the added VCap effect, and only Steve may give you the specs for it.  It's odd, but I thought Steve mentioned once that VCaps would not fit in the Mini-Torii (there are 4 Caps total), given their size.  He stated VCaps were not an option for the Mini Torii.

Anyway, good luck!
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Re: Mini Torii SE Amplifier
Reply #171 - 04/08/12 at 00:16:11
 
Fireblade,

the Vcaps did not add anything to the gain issue. Rivieraranch had warned me that they would add even more gain, however I haven't noticed an iota of difference. I had this issue even with my 2V cd player, with the stock volume pots of course.
I had read Steve's recent (feb 2012) post about Vcaps not fitting inside the MT. In light of my successfully installing 0.22 Vcaps in there, I do not fully understand. He also mentioned there are 4 caps to be replaced, which would make it expensive. That I can see immediately Smiley I do not know how big the 0.1 Vcaps are, maybe those would not fit indeed. Although where there's a will, there's a ... drill.  I still need to listen before I decide it was a good idea to replace the stock caps. I recently replaced a bad resistor and I believe it screwed up my soundstage focus. So far the Vcaps have brought about a vast change in musicality and detail (the kind of detail you would crave). Change is an euphemism, I dare not say improvement. For me and my ears. If anything though, the presentation may have become more forward, which I dislike. But like I said, it may be due to a few odd resistors I put in there, we'll see.
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Re: Mini Torii SE Amplifier
Reply #172 - 04/08/12 at 00:22:42
 
Here is a schematic of how to add a resistor in series with the signal input before the att, which is what Erik suggested in the first place and which I now have come to consider the easiest way out, in case I still have issues with it after I install the att.



add usable steps to attenuator par raduschkamuschka, sur Flickr


resistor values par raduschkamuschka, sur Flickr
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« Last Edit: 04/08/12 at 00:38:03 by Raduschka »  
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Re: Mini Torii SE Amplifier
Reply #173 - 04/08/12 at 01:52:28
 
Having a more 'in your face' or forward sound with the VCaps may contribute to the perception of inordinate loudness also.  

It's interesting from the schematics you upploaded to see how my earlier argument for a highly stepped attenuator, needing more clicks for the same arc sweep, is put into practice.  This is exactly what I think you need, although the reasons why you need it are vague.  Could be some of the resistors going bad you mentioned earlier.  I still wouldn't rule out the VCaps as a possible cause, though.

You need to discuss it with Steve, just to be sure. There must be a reason why he disaproves the VCaps in the Mini Torii.  Over and out! Smiley
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Re: Mini Torii SE Amplifier
Reply #174 - 04/08/12 at 02:12:48
 
It is not the V-caps. The info on the Goldpoint page is correct. High gain amp, hgh ivoltage source and efficient speakers with no xover
equals hair trigger volume control.

However, before I did anything I would wait for Steve's reply. I think he will have a solution.
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Re: Mini Torii SE Amplifier
Reply #175 - 04/08/12 at 02:59:00
 
So how do you explain the paradox (most people under similar conditions without an unmanageable gain problem)?  Of course the Goldpoint page is correct.  The issue is why it happens so dramatically in Radushka's case, relative to the rest of M-T owners.
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Re: Mini Torii SE Amplifier
Reply #176 - 04/08/12 at 03:00:17
 
Floridaboy

What I mentioned about this are the most usual ways of dealing with excessive gain....which I have dealt with over twenty years and from designing and building some of my own amps.  But doubtless you are right that Decware knows more about there products than anyone!  We are  just sharing ideas, which in my view makes for beneficial discussion.

He could also even use a variable L pad on his driver, selected to match the impedance of the same... But yuk, it would be better to take care of it at the line level, if by no other way than by putting a preamp between DAC and amp.  
 

Erik, I understand the sharing of ideas and I don't have any audio ego.
I hope the solution is simple. Now I am curious about how the high gain is achieved in the amp.
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Re: Mini Torii SE Amplifier
Reply #177 - 04/08/12 at 03:21:51
 
here is what the tech at Goldpoint told me (he seems to think the output impedance of the dac is overboard):

Raduschka,
Lower attenuator impedance is not directly related to better high frequency response necessarily.
In your case, however, it could be borderline. That's why we don't generally recommend stepped
attenuators above 100K for use with tube gear. But, you have an additional problem, and that is
the output impedance of your signal source is way too high, unfortunately. It should be below a
few 100 Ohms.

However, to start off with fixing up your system there, you either have to install preattenuation
(a 2-resistor voltage divider) or reduce the gain in your amplifier. In that way, the stepped attenuator
will be adjusted to work with your system. Instructions on how to do this are on the Goldpoint
web site. Find it on the DIY page. Handle this first. If you still have high frequency roll-off,
which you shouldn't, we can discuss alternatives at that point. But, it is unlikely that even with
1.3K signal source output impedance that you're getting high frequency roll-off.

Arn Roatcap
Goldpoint Level Controls
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Re: Mini Torii SE Amplifier
Reply #178 - 04/08/12 at 03:23:57
 
here is what i got from Eli Duttman od DIYaudio (I will need translation Smiley :

Applying the 1:10 rule of thumb to the DAC's O/P impedance of 1.3 KOhms tells us that 15 KOhms or a bit less will be adequate.  You really need to employ a padding resistor in series with each control to tame the "hair trigger" issue.  My seat of the pants guess is that a 4.7 KOhm metal film part in series with a 10 KOhm log. taper control will do the job.  You can always increase the padding value, if control is still "touchy".

No way do I spend big money on those Goldpoint attenuators.  Hot molded carbon controls made by PEC of Canada cost lots less and certainly have a "warmer" sonic signature.  PEC controls are milspec tough and also reasonably priced.  A pair of DigiKey stock # KA1031S28-ND is what I suggest you use.

BTW, hold the interconnect cable capacitance between DAC and amp down.
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Re: Mini Torii SE Amplifier
Reply #179 - 04/08/12 at 03:39:54
 
I would guess Floridaboy and Goldpoint have a point: High gain amp, hgh ivoltage source and efficient speakers with no xover
equals hair trigger volume control. Plus the output Z seems to be high, not that I really understand , but....
Once again, I was warned about the Vcaps adding gain and I did not notice any subjective difference, if that matters to anyone. This si no way a new issue, brought about by the Vcaps. And I also do not know how 'extreme' it is. Maybe it 'appears' extreme.
I am torn between all the interesting reviews of expensive attenuators and the cold showers of  savy people who suggest cheap parts.
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Re: Mini Torii SE Amplifier
Reply #180 - 04/08/12 at 16:08:59
 
Floridaboy: Noted, and I understand where you are coming from.

Raduscha: to explain the high frequency issue related to lower value potentiometers would take a long time.  I think, however, that you got sound (truly not an intended pun!) advice from Eli and elswhere.  The in-line attenuator I mentioned works very much the same.  And as I mentioned too, and of course just my opinion, that the output impedance of your DAC is just a wee bit high, but not at all unreasonably so.  Short ICs can be important in such cases, particulalrly in instances of higher output impedances in conjunction with passive volume controls, regardless of how much the cost or stepped or not.  This is because higher output Z has difficulty driving the capacitance associated with long lengths if cable.  So keeping them as ASAP (as short as possible  ::) is better than not.

The reason that your Vcaps might very mildly increased gain is because that type of cap, vs say an electrolytic (which, believe is or not, can be found in interstage coulping positions) is that they have rather low ESR (Equivalent Series Resistance).  Remeber awhile back or in an email I mentioned that even capacitors have elements of inductance and resistance? This is to what I was referring.

Here is something you can try: get a small box of some kind to use as a chassis.  Cheap plastic would be fine.  Drill four holes that are correctly sized for cheap RCA jacks.  Install the jacks.  Drill another hole to fit the shaft of a cheap potentiometer -- say 10k to start with, either linear or audio taper.  Install the volume control.  Do you know how to wire a pot as far as input, wiper (output) and ground?  One set of RCAs will be for the input.  The wiper, center lug on each section of a stereo control is the output in a standard configuration (there are different ways to wire a pot, including a shunt type of contro -- I'll talk about later, it's an idea that may help in ypur case, and have the added benefit of a potentially better sounding pot) will be connected to the output jacks.  Connect the grounds and potentiometer ground.  And run leads from the center of the input RCAs to the input lugs of the colume control.  And what you have just made is a very cheapmbut effective passive volume control.  Goldpointmsells these for a few hundred dollars.

Now plug your DAC into the input RCAs of the box, and the outputs of the box to the inputs of the mini torii.  What you end up with is what I suggested could be done using those two remaining holes in the mini torii, which is essentially a passive preamp built into the chassis. Trymit first the way I mentioned above.  Please, if I may say this, don't overly rebuild your amp right now.  Deal with the gain issues first, and then, perhaps do other modifications you might be interested in.  If too much is done too fast, you can end up feeling exasperated.  Ask me how I know! Undecided. What all of this is really sort of a variable rather than fixed voltage divider.  And apologies for spelling errors.  I have typed all of this very quickly.

Another note: the 6y6 may be my favorite tube with this amp.  It does run quite warm, but I knew that would be the case, as Florida boy also mentioned.  My dad, who is truly experienced in vacuum tube radio electronics often laughs at what I interpret as being hot as far as power supplly components go.  Moreover, I have a very good but low powered OTL amp that runs in single ended class A that will literally sizzle of I dampen my finger and touch the chassis.  Very heavy currents run through the chassis and the heatmis actually normal.  If you are not sure about anything I've written let me know and I'll explain it.
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Re: Mini Torii SE Amplifier
Reply #181 - 04/08/12 at 16:48:07
 
Erik and all,

This has been a good discussion for sure.  We all may have some small issues with this amp due to our associated components and it is impossible for Deware to make a 'one size fits all ' product. Since this amp is built to order it may be easy for Steve to reduce the gain a bit.

Fireblade,

I am not going to get worked up over this and neither should you. JMHO. Tubes, capacitors, resistors etc. are quite subjective. There is no best...only what sounds best to you. Me? I don't care for Teflon caps or Tantalum resistors...but you may. Hope this makes sense.

What I want from this amp is a good all 'round music machine, musicality before the ultimate in transparency. I have had rigs that were so revealing that I could only listen to a small percentage of my CD's and I do not want to go there again.
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« Last Edit: 04/08/12 at 17:59:02 by Les Lammers »  
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Re: Mini Torii SE Amplifier
Reply #182 - 04/08/12 at 18:14:34
 
FB,

I agree.  I just want to rule out potential shortcomings and prepare myself with possible solutions.  I won't be doing anything mod-wise until I hear it, totally broken-in, but these discussions help me learn more about its intricacies.  I don't know about you (with experience in these topics), but I want to learn as much as I can.  It's all part of the fun. Have a good listening! Smiley
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« Last Edit: 04/08/12 at 18:19:08 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #183 - 04/08/12 at 18:37:48
 
Let me also explain my intentions further.  I have two weaknesses in relation to music appreciation: Classic Bebop jazz and classical music.  From classical, I enjoy both orchestral works and smaller ensemble works.  These three different source types pose correspondingly different demands on the audio gear.  I envision eventually having sorted out two or three different setup configurations, aimed at each of these genres, as to tap the potential from the gear in each case.

One way to enable this adaptive process, other than blind trial-and-error, is to learn about the amp's inner workings, tube rolling and other tweaks that may help me identify possible setting tradeoffs for each particular type of music.

I prefer this approach than the one many people choose, namely, buying different amps/speakers for each particular application.  I think you end up really familiarizing with your particular gear and it may be a more practical (and economical) approach.  One can also learn a lot in the process.

So let the arguments begin ...  ;)
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Re: Mini Torii SE Amplifier
Reply #184 - 04/08/12 at 19:32:29
 
I really enjoy the fact that all  of a sudden the forum topic lights up and draws so much attention and investment. It has been pretty dead for a while.
Myself I specialize in psychotherapy, but I keep wanting more from my sound system and feel claustrophobic when limited. I know some of you have been playing around with audio for decades and were able to come to conclusions, but I can only make my own mistakes and find my own taste. Right now I am amazed by transparency, and how new parts can reveal more of what is hidden on those cd's. So far the setup has remained very musical. Maybe if I overdo it I will know (from experience) what it means to have an overanalytical system.
Erik, I understand very well the idea of installing volume pots on the incoming signal, before the amp's atts. I know how to solder volume pots, although I don't know much in general. I work deductively in electronics, which oftentimes doesn't take me far and sometimes backfires. Literally Smiley
After all this discussion I must say that if a new attenuator offers me ONE single click that I can use I will be satisfied, as long as it sounds better than those I have now, which I do not trust particularly. The gain issue is secondary for me and now I know how to solve it, thanks to your collective efforts, thank you very much.
So for me the question still remains whether I should get an att of the same value as the one the MT comes with (100k) or lower (50k or even 25k), given my present setup.
As for the Vcaps, my observations so far are of the hesitant kind, which dwindle from day to day and I need more time to say for sure if the soundstage is really more fwd, or perhaps I need to reposition my speakers etc etc, or perhaps I hear more detail or who knows. One thing is clear though, the sound has changed and I hear strings, let us say, which really sound like strings, metallic or not, to a degree that gives me goose bumps. That is an uncontrovertible observation, compared to the ones I mentioned before.
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Re: Mini Torii SE Amplifier
Reply #185 - 04/08/12 at 20:17:16
 
soldered back in the 240k resistors (took out 2w kiwame) and voilà! The soundstage depth and focus are restored!!! Phew!
I had replaced the 2k7 resistors to the input tube (from vol.pot out) with 2w Shinkoh and there was a marked improvement in detail. May try a 0.5 watt shinkoh one day. Once again, no change in gain whatsoever, don't go thinking it appeared after my mods Smiley
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Re: Mini Torii SE Amplifier
Reply #186 - 04/08/12 at 20:39:16
 
Radu

I hope I didn't sound like I thought you didn't understand what to do.  I  just wanted to clarify what I might have written in the way of a lousy or poorly worded description.  And I of course I don't know your electronics ability.  Steve, by the way, has to be one of nicest guys in the business.  I have talked with many designers over the years, and Steve is down to earth and a gentleman.  I of course can't speak for him or anyone, but I think he would understand the urge to tweak and experiment.  That's how this amp came into being after all.

And good grief it makes sense to have only one system that does everything well, fireblade.  Very good sense, in fact.  I think of that sometimes when I look at the two pair of huge horns staring back at me from across the room.  I love what they both do very well but differently, though!

Anyway, all have a good Sunday with your firends and family.  You'll get this gain issue solved, Raduscha!
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Re: Mini Torii SE Amplifier
Reply #187 - 04/08/12 at 20:59:10
 
no  no Erik, where did you get that idea?? I just said that I knew how to solder volume pots, in direct response to your question: 'do you know how to solder volume pots?' Smiley  Imagine if I strated feeling offended everytime someone helping me out fails to guess what I can and cannot do.....
I do apprehend explaining to Steve how I improved his amp, hahahah  ...wait, I am really laughing...arf arf...
but I suppose he'll understand. Anyhow , I wrote to him and am waiting to see if he thinks it is a substantial email.
For now I am happy that the resistors I put back in are not the faulty ones and that my perfect holographic imaging is back!!!! I had definite treble rolloff with the 2watt Kiwame. Now I feel ready for good atts. Please Erik, tell me what value I should get, 50k or 100k?? Please please,
I am now going out to buy groceries. Just thaught you all needed to know that.
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Re: Mini Torii SE Amplifier
Reply #188 - 04/08/12 at 21:08:53
 
" but I can only make my own mistakes and find my own taste. Right now I am amazed by transparency, and how new parts can reveal more of what is hidden on those cd's. So far the setup has remained very musical. Maybe if I overdo it I will know (from experience) what it means to have an overanalytical system."

It is a journey and only you can decide when and where to stop.

Here is a tip: Go slow with changes and give each one a good listening to before moving forward.
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Re: Mini Torii SE Amplifier
Reply #189 - 04/08/12 at 21:40:10
 
Wait ....  What 240k resistors had you removed?  Did you replace them with like values of some other brand?

I just got back from buyong groceries, and at mymdear wife's request, some paper towels!  You can never have too many paper towels!
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Re: Mini Torii SE Amplifier
Reply #190 - 04/08/12 at 21:56:08
 
I had replaced the 240k resistor btw pins 1 and 6 with a 2watt kiwame. I had replaced 2 pairs of resistors at the same time and lost the highs but solved a nagging right channel crackle and hiss problem. I put back the original 240k and  got back my dignity. And realized at the same time that the bad resistor was one of the 47k!!

The 47 k I have installed now are 2 watt audionotes. The 2 watt is overkill and possibly a wrong decision, will have to swap with 0.5 watters. But as is it sounds great too.
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Re: Mini Torii SE Amplifier
Reply #191 - 04/08/12 at 21:57:45
 
I love my girlfriend too Erik. She confirmed that the sound got back on track. I always ask her to listen to the same song, 'some days are better than others' on zooropa. The only U2 album I like.
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Re: Mini Torii SE Amplifier
Reply #192 - 04/08/12 at 22:00:45
 
Fireblade wrote on 04/08/12 at 18:37:48:
Let me also explain my intentions further.  I have two weaknesses in relation to music appreciation: Classic Bebop jazz and classical music.  From classical, I enjoy both orchestral works and smaller ensemble works.  These three different source types pose correspondingly different demands on the audio gear.  I envision eventually having sorted out two or three different setup configurations, aimed at each of these genres, as to tap the potential from the gear in each case.

One way to enable this adaptive process, other than blind trial-and-error, is to learn about the amp's inner workings, tube rolling and other tweaks that may help me identify possible setting tradeoffs for each particular type of music.

I prefer this approach than the one many people choose, namely, buying different amps/speakers for each particular application.  I think you end up really familiarizing with your particular gear and it may be a more practical (and economical) approach.  One can also learn a lot in the process.

So let the arguments begin ...  ;)


FB, I always chuckle when you say "classic bebop" because on jazz boards there are all kinds of arguments of nomenclature. "Classic jazz" is the New Orleans tradition and the 40's revival and the "Chicago Sound." "Bebop" is "modern jazz", and to call it "classic" can only make sense in this classificational world of jazz bulletin boards in referring to the very first years of modern jazz and its originators, that is "classic bebop" would just be the jam sessions at Minton's (some recordings) and so many other places that weren't recorded because of the "recording ban," and could maybe be stretched to include the first groups of Charlie Parker, Dizzy Gillespie, the Coleman Hawkins group with boppers, the short-lived Eckstine big band, etc.

Anyway, "classic bebop" is close to nonsense in that world! Gives me big chuckles to read. Thanks.

My real post is to say I commend your intentions. I hope you have on order the amp that will be THE amp for YOUR speakers and you can start right in on tuning the sound. My observation: I think you may discover as I have that there's ONE assemblage of tubes that is right for BOTH your jazz and classical recordings. One group that makes the amp sing it's unique song with the source material. I've found one that I can just pop in and spin rock, jazz, classical, Brazilian, blues, what's in my voluminous shelving. That's my prediction: you'll find one group of tubes that sets the amp free to show you what's on all the discs.
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Re: Mini Torii SE Amplifier
Reply #193 - 04/08/12 at 22:21:28
 
For the first time we are now testing with 15 ohm silver coil Lowther PM2As.  Tube compliment for the mini torii are 12at7 and 6y6.  This combination is just amazing....
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Re: Mini Torii SE Amplifier
Reply #194 - 04/08/12 at 23:32:44
 
Erik, I tested 6L6 tubes in my MT and did not like the presentation one bit. Things were pretty much out of focus, although the bass was great and everything sounded somewhat fuzzy. Someone on the forum told me that it sounded pretty much like what I could expect from 6l6's. Could you please resume in a nutshell what is specific to the 6y6 in the MT, as compared to the 6v6?
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Re: Mini Torii SE Amplifier
Reply #195 - 04/09/12 at 00:31:40
 
Lon,

As you should know, defining Bebop is already a very difficult task.  The only sure characteristic is the free improvisation license to all  musicians.  Within this very obscure and vague definition, there are myriads of styles possible.  I call classic Bebop, just as an example, the earlier works by Miles Davis, not the middle or final ones from his prolific and varied career.

I call Classic Bebop everything that encompasses music from Charlie Parker all the way up to earlier Hard Bop. Period.  So there you have my own definition of Classic Bebop.  It usually consists of music from the 50's and 60's, but extends up to the 70's in some traditional musicians (it's a style, not a chronological issue).  Also, the blues are very much imbedded in this style.

It is a particular style ideal for trios, quartets, quintets and even sextets, and usually combines solos from wind instruments (trumpet and sax, for example) or striing instruments (guitar) or vibraphone, in most cases interacting with piano.  Piano trios are the most basic ensembles for this particular style.  Although bass and drums are permanent side instruments in these arrangements, the Classic Bebop structure implies sections of the song including bass and drum solos, respectively, usually interacting with wind or piano leads.

Being very independent in my way of thinking and perceiving life, I could not care less about how other people 'classify' my description of this sub-component of jazz.  What is important for me to enjoy is the virtuosistic improvisation playing around a simple melody, that is used only as a vague reference throughout the session.  I admire musicianship at this level, and I'm also very taken by the simple yet moving effect of the bass rhythm throughout this musical structure.

In my personal appreciation, usually older or more modern attempts or interpretations are seldom to my liking, simply because they lack this acquired cultural ability to demostrate full command of their instruments around a simple melodic line, with great good taste and never boringly.  It is virtuosism, not showmanship.  For example, Charlie Parker was sometimes contaminated by this interest of showing off those wonderfull skills, sometimes to the detriment of the melodic structure.  Mostly, though, the man was unbelievable!

In my appreciation, the best exponents of what I call Classic Bebop are (in no particular order): Chet Baker, Art Pepper, Ben Webster, Charlie Parker, Miles Davis, Stan Getz, art Farmer, Coleman Hawkins, Gene Ammons, Gerry Mulligan, Duke Jordan, the great Bill Evans, Jim Hall, Jimmy Cobb, Lester Young, Roy Hargrove (modern old-style), Lionel Hampton, Cannonball Adderley, Arturo Sandoval, Benny Carter, Brad Mehldau (modern-old style), Bud Powell, Keith Jarret, Dave Brubeck, the great Oscar Peterson, Paul Desmond (by himself), Sonny Stitt, Sonny Rollins, Sonny Clark, Phil Woods, Duke Ellington, Freddy Hubbard, Dizzy Gillespie, Grant Green, Kenny Burrell, Johnny Hodges ... and countless others I can't remember just now.

So, there! You can chuckle all you want, Lon, this is my own definition of the best jazz style I've come to appreciate, and which has offered me innumerable hours of sheer listening pleasure.

Have a nice listening session ...
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« Last Edit: 04/09/12 at 02:20:04 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #196 - 04/09/12 at 00:54:32
 
Lon,

Regarding your prediction about a fixed set of tubes handling all music genres, I hope you got that one right.  It would be much easier to have a fixed set and know that the sound is relatively the best possible for the particular setting ...  Let's keep our fingers crossed, we'll see.
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« Last Edit: 04/09/12 at 02:15:44 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #197 - 04/09/12 at 00:55:54
 
FB, I love that stuff too, and the swing that came before it and the classic jazz that came before that and much that came beyond.

Sometimes when you talk to others about your interests you have to concede to nomenclature to avoid confusion. On my own I can call almost anything whatever I want to. But when I communicate with others there are some common touchstones I have to reference.

Most of what you are calling "classic bebop" I'd simply call "bebop" and would be called that on the boards.  Some of it more like swing, hard bop or perhaps even "modal jazz." Realistically, it could all be called "modern jazz."

It doesn't matter unless you're conversing in a community, which you aren't. Whatever it's called we love the music. I wasn't chuckling at you. I was chuckling at the attitudes of some of the posters I know well at your definition were you to proffer it in their little kingdoms. They don't matter, but they can be entertaining to me. I'm sort of a closet nihilist.

Have a fun evening. I'm hitting a few backroads.
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« Last Edit: 04/09/12 at 01:50:42 by Lon »  

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Re: Mini Torii SE Amplifier
Reply #198 - 04/09/12 at 01:05:41
 
Regarding the tubes: I use as a major reference to the basic sound for my systems recordings that I made in my then garage apartment of bands I rehearsed with and performed with and recorded rehearsals and demo tracks for. I used the same microphones, the same tape deck, and the same space for four different groups of musicians that included acoustic and electronic percussion over several groups, electric and acoustic guitars and basses and keyboards over several groups, vocalists and reed players and one crazy trumpeter over several groups. I know these recordings pretty darned well and the room and people and I myself participate in the music-making. It gives me a good reference. In all my tube systems I've been able to find a tube set that will represent realistically what I feel is on both the electric instrument material, the acoustic instrument material, and the material with a mix of both acoustic and instrumental material. When I get this set established, I can feel confident that my purchased recordings will be represented pretty realistically.

I therefore really believe it's possible, and will be interested to see if you discover this too in time.
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Re: Mini Torii SE Amplifier
Reply #199 - 04/09/12 at 03:10:19
 
Lon,

I did not think you were laughing at me.  And, to some extent, I agree we all need some conventionalisms.  But, I would argue that concept does not apply to this particular topic, as it is very subjective and full of inconsistencies.  I do agree the general term should be Bebop, but I'm always afraid of conveying a too open compass by that definition, as I don't really like a good portion of the music that may be included under this more general term.

Regarding the fine-tunning, I will also select specific reference material I'm quite familiar with, in comparing settings when the time comes.

I haven't been riding much lately, as weather here has changed already into frequent, randomly distributed heavy raining.  I usually can predict a few hours of dry weather very early in the morning, but not after that.  I think I need to change my schedules very soon!  8-)

Take care now ...
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« Last Edit: 04/09/12 at 03:13:03 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #200 - 04/09/12 at 03:20:17
 
Had a nice ride. We had weeks of rain in March and a few showers early this month, but it's already in the nineties here damnit and I can at least take advantage of the cool evenings for a spin!

Well, I don't really agree that this particular topic is any more full of inconsistencies as any other jazz topic, and I guess you have a right to say "classic bebop means only the bebop that I happen to like" but that seems a little silly! Smiley

Anyway have a nice night. Time to watch Mad Men.
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Re: Mini Torii SE Amplifier
Reply #201 - 04/10/12 at 00:21:44
 
Raduscha
The thing.....or let me restate this.  ONE of the things about valves is that not alll types or brands of the same tube necessarily sound the same.  Explaining in a nut shell takes the pressure off a bit. Smiley I did not find it to be the least bit fuzzy or vague.  It sort of sounded like a more robust 6F6, which was which I think is what I prefer for headphone listening.  The 6y6 with the 12at7 in front of it was, for some reason, a particulaly nice match with the high impedance Lowthers, and in that sense coupled with the speakers better, with better grip and bite than the 6v6.

We can't speak of any of this in absolute terms, of course, and this tube type preference issue is totally subjective.  My 6y6 in my system might in fact sound fuzzy or totally out of whack to someone else, and that is absolutely fine with me.  It's one of the reasons that it's nice that the Mini Torii was designed to be as flexible as it is.  If someone thought I was nuts about being interested in any of the tubes we have talked about, I would agree that I probably am nuts, but that I know what I like!
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Re: Mini Torii SE Amplifier
Reply #202 - 04/10/12 at 00:27:11
 
I see:-) I won't go anywhere near the 12at7 right now. I am curious as a cat to try out all of the 6x6 tubes. I understand of course the relativity issues. My speakers are 4ohm I think.
Coffee makes me write short sentences. Maybe I should drink it more often before posting.
you all wish
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Re: Mini Torii SE Amplifier
Reply #203 - 04/10/12 at 00:48:37
 
Erik...we are all a bit crazy and I agree 100% on the system dependency and synergy of tubes.

Radushka,

You are too funny! You might find a container of coffee on your doorstep...decaffinated.  ;D

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« Last Edit: 04/10/12 at 00:49:05 by Les Lammers »  
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Re: Mini Torii SE Amplifier
Reply #204 - 04/10/12 at 01:36:32
 
The sentence I wrote above about the tube I think I like most for headphone listening is ridiculous! LOL

Time for bedtime reading....what else.... Stereophile, Hi-Fi+, it never ends..... Your are right Floridaboy.

Until later, erik
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Re: Mini Torii SE Amplifier
Reply #205 - 04/10/12 at 01:41:00
 
have a nice sleep all of you while I listen to my favourite band: MT Vcap Auricap Haytron 6v6. They play all kinds of genres, including classic bebop.
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Re: Mini Torii SE Amplifier
Reply #206 - 04/10/12 at 03:16:02
 
Fireblade,

now that I think of it, I also have strange issues with my 6x4 whistling in my MT. I have a couple of them that I can't use because they whistle loudly. Not through the speakers, just by themselves. I haven't seen anyone report that kind of phenomenon here on the forum. If I am a rare case, perhaps I could measure the resistors running from my 6x4s and compare them against the spec value, if someone knows it. Otherwise I will call Steve. I warn you Smiley
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Re: Mini Torii SE Amplifier
Reply #207 - 04/10/12 at 13:05:03
 
In spring 2011, Steve decided to replace the 6x4's with EZ81 rectifiers.  I don't know the reasons for this, but it may have to do with that problem.  In any event, I suggest you talk to Steve, and maybe get the list of adjustmentss required to migrate from 6x4's to EZ81's in your amp.  

I would also ask him about the effects of the VCaps in the M-T.  These may pose no problems and maybe they are ruled out due to space constrictions only, but there may be something else.

I would also make sure somehow, the loudness sensitivity issues you are experimenting are a perception and not a real problem.  This is important to rule out 'organic' problems with your gear.

I hope you solve those problems soon.  Good luck!
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« Last Edit: 04/10/12 at 13:06:41 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #208 - 04/10/12 at 22:55:19
 
The reason for the switch from EZ90 (6x4) rectifiers to EZ81 (6CA4) was because the 6x4 sounded great, but was the weak link in the amp. My own experience proved this when some, frisky, 6Y6's blew out one of the 6X4 rectifiers
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Re: Mini Torii SE Amplifier
Reply #209 - 04/10/12 at 23:42:30
 
My experience with valve rectified power supplies is that various rectifiers are intended to be used with specific amounts of maximum capacitance in capacitor input to filter based supplies.  It's less critical when an inductor is used as the input to filter.  In other words, it may not be so much a case of output tube destroying a rectifier as it is the first element in the B+ ripple filter.  From what I remember -- and want to double check this because I have been curious about it -- the rated capacitance for 6X4 cap input to filter design is 10uf.  If an amp with a 6X4 were designed with say 50 or 100uf capacitor right off the rectifier, that can cause a problem.  For example, about 15 years ago I built an amplifier (2a3 single ended) that used a very hoghly regarded Mullard GZ37 rectifier.  That tube is intended for about 4uf in the way of the input to filter capacitor.  However, the design I built used a 10uf capacitor, which is twice the suggested value for the type of filter used.  And we experienced some rectifier failure.

Not saying or implying this is an issue in the MT, but is something I intend to check the next time I open it up.  A schematic sure would be helpful.  I can draw one out long hand by studying the circuit design, but it's just a very time consuming thing to do.  I have schematics for all the amps I have built over the years.  Not this one, though.
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Re: Mini Torii SE Amplifier
Reply #210 - 04/11/12 at 01:17:38
 
So, if some might be worrying or wondering -- the capacitance rating of the EZ81 for capacitor input to filter design is 50uf.  My MT uses 33uf as the first cap after the rectifier, which is well within tolerance.  The other nice thing about the EZ81 is that it's an indirectly heated rectifier, whereas the 6x4 is directly heated.  Thus, the EZ81 provides a more gradual voltage increase (aka slow turn on) compared to the instant in-rush of solid state diodes and quicker, directly heated valve rectifiers).  If 33uf had always been the value of cap input capacitance, it may over time have eventually taken its toll on the 6X4.  Seems a very prudent thing of Steve and Decware's part to change to the EZ81 -- for a number of reasons, what is mentioned above, perhaps, being possibly associated with it.
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« Last Edit: 04/11/12 at 01:31:54 by erik2a3 »  

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Re: Mini Torii SE Amplifier
Reply #211 - 04/11/12 at 23:51:56
 
Regarding the choice of coupling capacitor: VCap or any capacitor can be used if the working voltage specifications and values are appropriate for the application.  Mild caution is encouraged in the sense that this is an area that can become an area of too much concern, IMO and at least in my experience.  Lots of builders, and something I've done myself, also experiment with the type of capacitor (as in oil or poly tubular type) used for the aforementioned input to filter capacitor, the first capacitor off the rectifier.  Same goes for the cathode bias resistor bypass capacitor.  

I want to just offer my opinion, which is of course nothing more than an opinion, that what I found so refreshing about this particular amplifier is that the circuit, which in my view is far more critical than the type or brand, rather, of passive parts used, is one that is not dependent on ultra expensive parts to provide, again in my opinion, extremely satisfactory performance.  The most expensive cap in the world is going to do nothing for a compromised design, and in fact might it even worse.  I tend to enjoy experimenting with some of the different tubes that can be used in the MT as a way of finding what works best for us -- and leave the basic circuit as it is.  Certainly one should feel free to do other things if one is so inclined.  If you don't have experience working with high voltage circuits, however, you MUST realize that the shock hazards posed can be extremely serious.  I knew someone once who took this rather lightly and the following week got zapped terribly hard -- by an amplifier that wasn't even plugged in.  The very heavy charge came from power supply reservoir capacitors in an amplifier that did not use a bleeder circuit, as it's called, on the output of the power supply.  I remember how this felt, because the person was me.  Be sure to measure the storage charge with a volt meter before doing ANYTHING.  There are safe ways of releasing these dangerous voltages, which do NOT include simply shorting capacitors to ground. If you're not sure about what you're doing, don't take the chance and get help.  Apologies, but I have to say this.....
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Re: Mini Torii SE Amplifier
Reply #212 - 04/12/12 at 00:07:59
 
Erik,
every single time I open up the MT I measure compulsively all 8 caps in the power section, although the 6x4 caps hold no current. I always get around 30V each on one side and 20V each on the other side... I discharge them using a led soldered to a 100k resistor to ground. Does that sound acceptable?
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Re: Mini Torii SE Amplifier
Reply #213 - 04/12/12 at 01:07:50
 
Radu: 20 or 30 volts is much better than 500, and you've got the right idea for bleeding off the storage charge, providing the resistor is a high wattage, power type.
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Re: Mini Torii SE Amplifier
Reply #214 - 04/12/12 at 01:23:49
 
What's also pretty cool about the Mini Torii is that they achieved such a vanishingly low noise floor with AC on filaments.  It's a very classic way of wiring the amp, and in this case clear proof how good AC heater supplies can sound.
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Re: Mini Torii SE Amplifier
Reply #215 - 04/12/12 at 02:07:19
 
The way this amp is designed, with such a flexible and robust imbedded tube rolling platform, I believe there's plenty of experimentation potential just by trying out different output, driver and regulator tubes, for anyone to play with, for years.  The possible number of combinations is staggering.

I'm assuming, of course, the amp sounds good enough to satisfy serious audiophile enthusiasts, to the point where the most probable improvement should come from other components in the setup.  Tube rolling would enhance specific character, timbre or tone differences, but always with audiophile SQ results.

Therefore, I would not attempt to change basic design parameters, and would settle instead on a couple chosen tube configuration sets as a reference for my particular system, to be able then to judge everything else.

This is evidently just MHO.  I suppose technically experienced owners may probably disagree, although I think most users will go about it as proposed.  

BTW my M-T order is already on "Parts Pulled"   Hurray!!!   Cheesy

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« Last Edit: 04/12/12 at 02:13:20 by Fireblade »  

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Re: Mini Torii SE Amplifier
Reply #216 - 04/12/12 at 02:24:11
 
to me the MT is a fantastic little amp which manages to sound incredibly good with not so fancy parts. I of course rolled tubes neurotically until I hit a wall and could not go any further, so... I decided to roll caps Smiley It was a year long transition from no experience at all, where I worshipped the MT as a fetishistic object that I would have to ship to the USA for 200$ a shot in case anything went wrong to now, where I tenderly solder and unsolder parts inside it like a surgeon would operate on a beloved one, or himself. I am slowly becoming one with my MT and feel sad or joyful, just like the sound that comes out of it, depending on what I have just installed, whether it is Mundorf or Vcaps or Khozmo attenuators... I for one found that a change  of cap brought about change impossible to obtain through tube rolling. As always, I make no claim to exhaustive scientific research.
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Re: Mini Torii SE Amplifier
Reply #217 - 04/12/12 at 02:37:55
 
Point well taken.  I assume this evolution may take place eventually, especially if one does not live in the US (like me).  But in my case, although I'm the analytical type, I'm very clumsy with my hands ... So unless I'm confronted with a real problem and forced to do something about it, I think I would hesitate to even open that chassis.

Good for you!
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Re: Mini Torii SE Amplifier
Reply #218 - 04/12/12 at 11:30:21
 
Radu:  believe me when I say it's possible to bump into that same wall with capacitor changes (I intentionally refrain from the use of the word 'upgrade' regardless of cost).  What can begin to happen over time with frequent trials and their often attendant errors, is that other parts next to or near those being switched in and out can begin to suffer as well.  Excessive heating from the iron isn't beneficial, and tube socket pins can begin to fatigue and actually even eventually break.  But as I mentioned to you, I completely understand the urge to experiment.  Being very familiar with a specific sound I like to hear feom an amplifier, I found the Mini Torii quite well balanced from top to bottom from the get-go.  Once a deaigner completes am overall circuit design, small subjective changes can be obtained -- seasoning to taste, as it were -- with coupling capacitors, and so forth.  Parts are not at all necessarily chosen because they are the most or least expensive, but because they sound correct without respect to cost.  

So, anyway, just my $.05 worth.  A minor point of interest I do have is concerned with the value of the first capacitor coming off the rectifier.  In the case of the 6X4, 10uf at 450VDC is not so large that it wouldn't fit if it were a poly film capacitor rather than an electrolytic, but again, whether an improvement (vs simply a change) were obtained is certainly not something all would agree upon, and, moreover, adds to the cost of the final product.
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Re: Mini Torii SE Amplifier
Reply #219 - 04/12/12 at 11:35:34
 
The EZ81 also of course has the added benefit of being a more rubust rectifier in terms of current delivery.  If your amp is using the earlier rectifier, it might just be worth giving that some consideration.  Have a great day, erik
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Re: Mini Torii SE Amplifier
Reply #220 - 04/12/12 at 12:46:46
 
Yes, there is a point where it must stop, despite the urges. In my case this is the first time I do this, so I have years in front of me hopefully Smiley So far so good, I only swapped a few things.
off to work
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Re: Mini Torii SE Amplifier
Reply #221 - 04/12/12 at 13:29:38
 
"I for one found that a change  of cap brought about change impossible to obtain through tube rolling."

Me too. These 'small parts' are like spice and I use them to get the 'sound' I prefer. What works for me may not work for someone
else, your associated gear and room also come into play. The high price parts are not always what will work best in your system. It's all about synergy. However, you can't 'fix' a poorly designed amp
with tube rolling and/or caps and resistors.
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Re: Mini Torii SE Amplifier
Reply #222 - 04/12/12 at 13:37:59
 
I am finding this out as we speak Smiley
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Re: Mini Torii SE Amplifier
Reply #223 - 04/12/12 at 14:08:58
 
I have a question, since I do not know much about much:

The volume of the first step on my att is too loud for late-night listening. I have 2 switches available near the inputs on the MT. Can I add two switchable resistors OUTSIDE the signal path, that i can switch on at night and reduce the signal going into the atts and switch back off during the day? If not I guess they can even be IN the signal path, if I can switch them off during the day.
Thank you
ps: and if so what value should they be to achieve useful attenuation?
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Re: Mini Torii SE Amplifier
Reply #224 - 04/12/12 at 22:06:12
 
does this look right to anyone?  switchable 47k from rca hot to rca ground to achieve 6db attenuation on demand...


47k par raduschkamuschka, sur Flickr
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Re: Mini Torii SE Amplifier
Reply #225 - 04/13/12 at 02:47:30
 
duh... I figured it out finally. I am afraid there is no way to attenuate the signal without adding an extra resistor in the signal path. Unless I swap some of the resistors in the atts, to make them get silent more abruptly.



mike2 par raduschkamuschka, sur Flickr
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Re: Mini Torii SE Amplifier
Reply #226 - 04/13/12 at 10:38:09
 
When did gain become an issue? The AN 2.5 volt DAC? Was it after you went to the OD3 or was it always an issue? There has to be a simple mod to reduce the gain but I am not technical enough to help.
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« Last Edit: 04/13/12 at 13:47:16 by Les Lammers »  
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Re: Mini Torii SE Amplifier
Reply #227 - 04/13/12 at 11:26:05
 
Do you have the same problem with the analog output from your CDP? IMHO, pehaps an extra series resistor or small voltage divider is not such a crime.  I also know there are people who use a good preamp, passive or active, between a DAC and amplifier -- because it works.  I'm just wondering if going straight from the cd player to the amp would be an improvement.

In any event, best luck working this out -- enjoy listening to some music this weekend, as well.
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Re: Mini Torii SE Amplifier
Reply #228 - 04/13/12 at 15:37:03
 
Decware's ZStage literature quote:

Just plug the ZSTAGE into the back of your CD player or DAC and you will have the power of an adjustable output level ( from zero to over 5 volts!) which means DYNAMICS are now in your control!  Not to mention the beauty of pure single-ended triodes adding dimensionality to your music that was never there before!

Just my $0.02. It's my next step after break-in.   Wink
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Re: Mini Torii SE Amplifier
Reply #229 - 04/13/12 at 22:33:34
 
I received instructions on how to lower the output voltage of my dac from Brian of AudioNote, by swapping one resistor and playing with various values. If there is no trade off that I am not aware of right now, this seems to be the most elegant solution.

You bet I will build my own preamp and use my new Khozmo atts in it Smiley
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Re: Mini Torii SE Amplifier
Reply #230 - 04/13/12 at 22:39:01
 
Valuable few cents worth, too.  I think its' a great idea, and of course we must respect Radu's desire to keep things as simple as he wishes them to be.  I remember feeling justas he does.  The inline attenuators I mentioned would help, too.  You out there Radu? Smiley i have those 6dB attenuators if ypu want them.  I think you might meed more than that, but maybe not!  Send your address and I'll mail tomorrow.
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Re: Mini Torii SE Amplifier
Reply #231 - 04/13/12 at 22:41:37
 
Oh, there you are.  Keep us informed with how this works out. Erik
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Re: Mini Torii SE Amplifier
Reply #232 - 04/13/12 at 22:43:00
 
i 'm here Erik! That sounds great, you are very kind. Let me try my new idea tonight and if it doesn't work i will try resistor attenuation, especially since now I understood how to wire those resistors. The tech from Partsconnexion, after seeing my drawings said: you are a good artist but you still don't get it.... Smiley

I will solder 2x  2k7 resistors in parallel with the 330R in the dac to lower the resistance to about 290r. Is that electrically correct?
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Re: Mini Torii SE Amplifier
Reply #233 - 04/13/12 at 22:48:41
 
Fireblade,
changing my DAc's output voltage...isn't it similar to using a preamp to match the gains and get great dynamic performance? Not a rethorical question, but a real one... Anyhow, i am not plugging my CD's dac into my amp again as long as my DIY AudioNote dac is functional!!!!!!!!
Ever!!
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Re: Mini Torii SE Amplifier
Reply #234 - 04/13/12 at 22:54:09
 

Untitled-1 par raduschkamuschka, sur Flickr
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Re: Mini Torii SE Amplifier
Reply #235 - 04/14/12 at 00:06:25
 
Raduscha:  remember I said I was an art teacher?  I had thought you could sketch quite well, and with the last drawing above, some very nice use of foreshortening and value.  Your style reminds me a bit of the expressive quality of Van Gogh's achromatic drawings.  Really, I like your work!  Okay, I get it loud and clear that you don't want to go straight from the CDP to the amp.  :)
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Re: Mini Torii SE Amplifier
Reply #236 - 04/14/12 at 00:29:00
 
Zbox really does look pretty good.  I was wondering if it might be based the familiar cathode follower topology, but probably not.  Output impedance is not really low, but not overly high, either -- a bit lower it seems than the audionote.  Nice powder coated finish, too.  I'm glad Fireblade brought this up, because I didn't even think of it!
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Re: Mini Torii SE Amplifier
Reply #237 - 04/14/12 at 00:37:00
 
I think you mean ZStage. ZBox won't help, no extra gain.
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Re: Mini Torii SE Amplifier
Reply #238 - 04/14/12 at 00:38:15
 
thanks Erik, I remember you told me that. Thanks
I should post more of my work Smiley
i am on to something here. I added 2k7 on top of 330R and lowered the output voltage (I am told) by some amount. I should measure with the 1khz signal from audioNote and I will. I will try to find a lower value resistor around the house to see what happens if I lower it some more, because as is it is still loud for late at night.
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Re: Mini Torii SE Amplifier
Reply #239 - 04/14/12 at 01:49:00
 
370 r on top of 330r lowered the output voltage even further. Should be ok for late at night and am in the process of listening for changes in dynamics. I am actually listening to music! Brian ENo and Robert Fripp, Equatorial Stars.
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Re: Mini Torii SE Amplifier
Reply #240 - 04/14/12 at 02:12:40
 
What? You call that music? Smiley Just kidding. Glad you're listening to music.
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Re: Mini Torii SE Amplifier
Reply #241 - 04/14/12 at 02:30:11
 
haha,

is that an inexact category again? Smiley
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Re: Mini Torii SE Amplifier
Reply #242 - 04/14/12 at 03:08:18
 
Radu,

Lowering the DAC's output voltage will help you attain a lower volume at that 2nd click, but it does not necessarilly have any effect upon dynamics, IMHO.

The idea behind 'riding the gain' to improve overall dynamics, is to accumulate unreleased gain potential on the input side, so as to be able to release a fraction of it through your amp's volume controls (output side of the equation).  With the ZStage in place, you achieve the desired end volume control, plus the dynamics effect.

It also works the other way around: If the music source is heavy and congested, lean up the input side and increase the conditional volume (end volume is the compounded effect of both input and output controls) on your amp, for a leaner, more transparent sound.  This, also attainable at the desired optimum end volume setting.

One thing is to correct the hyper sensitivity of your amp's volume control (just reducing the DAC's output voltage), another, more synergistic approach, is to achieve the same results but with added, more lively dynamics.

I may be wrong, but this is how I see it.   Great drawings, BTW!
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Re: Mini Torii SE Amplifier
Reply #243 - 04/14/12 at 03:17:32
 
A tube gain stage should be easy to make.... I just need to find a schematic.
But won't it add a layer of circuitry between the source and the amp? A new pair of pots, etc...
I just got a pair of pretty expensive atts!
Won't it blur the details in exchange of better dynamics? I never used a preamp, so please forgive the amateurism.
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Re: Mini Torii SE Amplifier
Reply #244 - 04/14/12 at 03:21:54
 
oh wait, I got it! If I make a tube gain stage I can take out the attenuators from the MT and use it as a power amp? Is that the idea?
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Re: Mini Torii SE Amplifier
Reply #245 - 04/14/12 at 03:42:07
 
Yes to your first question, no to the second.  Indeed, with the ZStage there's another component and a pair of added cables involved, which, from a purist viewpoint, is not ideal.  But in return, you get boosted dynamics.  Decware's components are really transparent, so the ZStage should not pose much in terms of degradation relative to more common preamps.

You already ordered the attenuators and I would suggest (if you want the added benefits of increased dynamics), to replace the current volume pots on the M-T with them.  Then, you can plug in a ZStage (or CSP2+ if you need more inputs) in the signal path between the DAC and the M-T and get the best overall results.  Make sure to use short, good quality IC's.

If you can build your own ZStage-like version, that's even better, except make sure it ends up being really transparent, otherwise you run the risk of adding non-insignificant sonic degradation.

In the end, the attenuators can be useful at pinpointing the exact volume you want (both day and night sessions), and the ZStage will improve upon sound dynamics.  Best of both worlds, on top of already having installed those great VCaps.   Wink







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Re: Mini Torii SE Amplifier
Reply #246 - 04/14/12 at 03:45:18
 
I love your optimism Fireblade! All I need now is a schematic and I could start gathering the parts.
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Re: Mini Torii SE Amplifier
Reply #247 - 04/14/12 at 04:33:28
 
this is the analog output board of my DIY audionote dac (6922 tubes)I rewired the original pcb in point-to-point on a piece of crap-wood from the 1$ store Smiley
If I made the output of this dac variable, would that equate to a zstage? Or rather a zbox, because I couldn't push it higher than its maximum 2.5V. Is it necessary to go up to 5v in order to be able to 'ride the gain' on the MT?

audionote dac2.1 ptp par raduschkamuschka, sur Flickr
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Re: Mini Torii SE Amplifier
Reply #248 - 04/14/12 at 04:35:44
 
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Re: Mini Torii SE Amplifier
Reply #249 - 04/14/12 at 07:24:38
 
I am about to build a zstage, based on the kit4 schematic provided by Steve on the website. i assume this is the same concept as the finished product, minus the frontal switch and the 0c2 rectifier. I ordered parts from partsconnexion and I happen to have a lot of useful parts, including a great transformer that came with the zkit1. I have the auricaps he uses in the zstage, one stereo alps pot lying around, one great 6922, etc. I just do not understand where the solid core copper wire goes from the input rca's. It goes straight to the tube alright, but what does it do there? Shouldn't it rather go to the volume pot ground?
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Re: Mini Torii SE Amplifier
Reply #250 - 04/14/12 at 12:22:43
 
Lon: I surely mean ZBox for the very reason that is simply an interstage impedance buffer.  Gain is the last thing that is needed in this case.  However, the input  voltage to it can be attenuated, which is precisely why it is particularly well suited here.  The output impededence spec. satisfactory, but not really low, which wouls be better, and have the additional capability of being able to drive the increased capacitance associates with longer ICs.
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