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Mini Torii SE Amplifier (Read 74700 times)
Les Lammers
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Re: Mini Torii SE Amplifier
Reply #300 - 04/16/12 at 22:11:05
 
Radushka,

Were you a surgeon in another life?  :)
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« Last Edit: 04/16/12 at 22:12:44 by Les Lammers »  
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #301 - 04/16/12 at 22:18:20
 
we only have two lives: the second one begins when we realize that we only have one Smiley

Confucius?
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Les Lammers
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Re: Mini Torii SE Amplifier
Reply #302 - 04/16/12 at 22:39:41
 
Confucious? Na....I Confused.  :)
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« Last Edit: 04/16/12 at 22:40:03 by Les Lammers »  
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erik2a3
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Re: Mini Torii SE Amplifier
Reply #303 - 04/16/12 at 23:48:32
 
This is going to be brief as I can make it: the capacitor that comes immediately off the high voltage (B+) output of any valve rectifier is often called the capacitor input to filter cap.  Different tube rectifiers have differing values of capacitance for which they are designed to be used.  Exceeding that value by a considerable margin can increase the chance of possible (but not necessarily certain) rectifier failure.  Of course the EZ81 can be used with a 10uf film cap.  However, the lower value will also result in some reduction of plate voltage.  If you adapt the circuit for the Ez81, however, there is no need to change the 47uf that's in there right now.  In many such power supplies there will be a filter choke after this first capacitor, and then another capacitor after that -- the value of which can be much larger than the input filter cap.  There are also power supplies that use a choke as the input to the power supply ripple filter. Which offer both better regulation as well as less concern about the value of capacitance after being damaging to the rectifier.  The 47uf has and will most likely continue to work okay, but...one can't say for sure that it's longevity might be less than with something more in the range of what is listed in data sheets for the tube.  I tend to play this moremon the safe side just because I have had problems with it in the past.

Allow me to say that I can completely change the internal components and overall voicing of this little amplifier.  My situation is that I have done SO MUCH modifying, rebuilding, using piles of different wire for hookup, IC, and speaker, that I just have no interest in it any more -- mostly because for me the overall circuit design is paramount, and even more because the Mini Torii sounds pretty awesome as is. I have three other amplifiers I'm working on right now because they require it.  What is so refreshing about the MT is that, just in my view and for my needs right now, it's always  there, just as it is, and sounding splendid. Little bit of tube rolling has been neat and yeilded some changes that put it in even better company with the stuff it's used with, both music and hardware.

And Raduscha!  I am glad you're enjoying the effort to make this even more your own amplifier.  That's what this is about! Cheesy  May I ask why you're soldering both leads of that twinaxial cable to the VC inputs?  You do have the sheild connected to ground on the other end of the cable, don't you?
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« Last Edit: 04/17/12 at 01:07:11 by erik2a3 »  

Have fun!
erik
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Les Lammers
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Re: Mini Torii SE Amplifier
Reply #304 - 04/17/12 at 00:12:06
 
Erik,

Those are certainly words of wisdom! I was going to change the caps
in the amp but I think I will give it 500 hours or so and then think about it.

Les
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #305 - 04/17/12 at 01:32:30
 
Erik, that is an old photo of the stock pots.
I just ordered 2 solen 10uf 630V caps.

I am glad I waited over a year to start modifying anything in my MT. That way i got familiar with its potential as is.
Improvement only makes sense if there is something to improve upon.  I say improvement because, while other parameters have simply changed, which is a matter of taste, others have improved, such as detail and bass coherence. That builds upon the mT's initial capabilities.
I am also slowly losing interest in hoisting the amp daily to the operating room/kitchen table. Especially since it sounds so good these days. Now I can only improve upon my mind. Change the value of its resistance and rewire a few things... Tighten a few screws...
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Fireblade
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Re: Mini Torii SE Amplifier
Reply #306 - 04/17/12 at 02:57:42
 
Talking abut loose screws, I was loosing it for the long wait.  But guess what, guys:  

On Bench - Means your order is now being built.   Yippiiii!!!!!   Cheesy  (speakers have been ready for a while now).    YES!!
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Laptop-Foobar2K-ASIO Direct//WD 2.0Tb HDD//Audio Gd USB cable//Audio Gd NFB 3 (2014) DAC//Decware Silver Ref IC's//Decware Mini Torii SE//Kimber Kable spkr cbls//Decware DM945's//Velodyne DLS 3500//BJC SUB Cbls//Tripp Lite 500 Isolation Trnsf.//Jellyfish Pwr Cord
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #307 - 04/17/12 at 03:00:57
 
Happy for you Fireblade!

what speakers are those again?
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Fireblade
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Re: Mini Torii SE Amplifier
Reply #308 - 04/17/12 at 04:07:05
 
Those are the 'small ones with a BIG sound': DM945's (4 Ohms version).  Thing is, I could not fit anything larger in my listening area without the wife complaining about decor issues ...  :-[   Thanks for asking.
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« Last Edit: 04/17/12 at 04:09:28 by Fireblade »  

Laptop-Foobar2K-ASIO Direct//WD 2.0Tb HDD//Audio Gd USB cable//Audio Gd NFB 3 (2014) DAC//Decware Silver Ref IC's//Decware Mini Torii SE//Kimber Kable spkr cbls//Decware DM945's//Velodyne DLS 3500//BJC SUB Cbls//Tripp Lite 500 Isolation Trnsf.//Jellyfish Pwr Cord
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erik2a3
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Re: Mini Torii SE Amplifier
Reply #309 - 04/17/12 at 11:32:01
 
Raduscha:  ah, that makes sense.  A case of my misreading, always being in a rush, that sort of thing.  I was wondering why the old pots were in there with what I thought you were sharing in the way of new signal wire.  Speaking of which, since you are experimenting, one can sometimes obtain good performance with a twisted pair of fine wire for signal and ground from the input jack.  Twisting AC leads, which you can see in the amplifier for the filaments, primary, secondary, and grounded high voltage and filament winding center taps help prevent emission of stray hum from AC, where twisting signal and ground leads as mentioned above helps give a bit of immunity to the picking up RFI/EMI since one of the wires used is grounded, just as the shield is grounded in common coaxial cable. There is just so little current in low, line level signals that heavier wire isn't needed.  I'm actually wondering now if I should have even mentioned this!  I think maybe the time might be near for just allowing that little patient to reover and return to work, though I do see that Solen is donating a couple of new capacitors intended for transplant.  Good choice! They are IMO and IME veryngood for the price, and perfectly suited for this application.  Glad you went for the 630V version too.  If you are handy with a multi meter, I would check before and after anode voltages.  A mild drop will not do any harm.  You want to keep things within a certain tolerance, but 10uf is still high enough, I think, to keep you in the ball park.  Please allow me to urge CAUTION! You are working with an energized circuit and need to be sure of what you are doing.  I wouldn't even suggest this, though you have checked DC voltages, as you said, in the past.  The difference here is that the amp is on and thus creates a potentially lethal shock hazard.  If you are even a little bit hesistant, please just make the capacitor change and leave it, or have someone who is familiar with high voltage circuits to check it for you.  Apologies, and please understand I am not questioning your competence, Raduscha.  I just want to confirm a statement is made about this dangerous aspect of audio DIYing.  Use the clip of your volt meter for the ground connection, and take the B+ readings with the other probe using only one hand. Put your other hand in your pocket.  Make sure the storage charge from the capacitor you are removing has bled off before handling it.  Have fun and maintain a healthy respect for electricity Wink
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Have fun!
erik
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erik2a3
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Re: Mini Torii SE Amplifier
Reply #310 - 04/17/12 at 11:59:06
 
And FWIW: this cap input filter modificationmay indeed turn out to be more than just a rectifier suitability change.  Film capacitors in this position are often believed to result in some sonic improvement over an electrolytic.  There are other capacitor types commonly for this purpose, but lets just leave as is right now.  I'm just adding to what I wrote above to say that you might find you like what you hear as a result of the swap.  I hope you have had a nice visit with your family!
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Have fun!
erik
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #311 - 04/17/12 at 15:34:48
 
Erik I understand perfectly your words of caution. You could even explain to me how to tighten a nut and I wouldn't feel offended. I think you still refer back to when I answered your question regarding wiring volume pots Smiley Believe me Erik, just a few weeks back I was looking that up on Google, to learn how to wire volume pots. It is a natural process and I display a certain degree of 'beginner mind' Smiley Plus I think you assess my skill level fairly well and do not have a patronizing attitude at all. QUite the opposite. There's a compliment for you!
The hardest part would be to have the MT plugged in and open at the same time, since the heavy transformers don't make for an equilibristic setup. I could place it squarely on its head and use a cheap flexible computer power cable instead of the stiff ones I have.

Fireblade, I built a pair of small floorstanders based on a Fostex 4 or 5 inch driver and, with the speakers being so small, the music was simply floating in the air with no apparent source and going back 5 meters into the room. The resolution was not so great though compared to the AN and I had botched up the ports so the bass was inconsistent. I am looking forward to reading your impressions of the dm945 with the MT.
I know someone who had small bookshelf speakers (like you will) who told me that the soundstage was so much bigger than his listening room that when he opened his eyes he felt like vomiting! (That's cause his brain couldn't compute the spatial clues).
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Raduschka
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Re: Mini Torii SE Amplifier
Reply #312 - 04/17/12 at 15:48:03
 
and on the same topic:

“By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest.”
― Confucius
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Les Lammers
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Re: Mini Torii SE Amplifier
Reply #313 - 04/17/12 at 16:31:24
 
I saw my Shrink yesterday and my Audio Nervosa is under control. Got meds, blue M&M's, and I have to recite 'I will resist changing anything until the amp has a lot of hours on it.'
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Fireblade
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Re: Mini Torii SE Amplifier
Reply #314 - 04/17/12 at 16:33:23
 
Radu,

To me, wisdom is realizing and accepting we'll never know much at all!  I have over 30 years of a varied professional experience, having lived in several very different cultures, and these days I find myself always asking and considering everyone's opinions, about most issues.

Regarding the speakers, I have high expectations from this design.  If you look at the specs, they carry 8" woofers and planar ribbons for the higher frequencies.  In contrast, my current setup consists of JVC wooden baffles & cones 4.2" woofers and 1" wooden baffle & cones tweeters.  They look great and sound ok, but there's going to be a huge difference with the DM945's, also because the sensitivity of the JVC's is just 82 dBs and they are physically very small.  I currently use a Velodyne Sub-Woofer to compensate for the lacking lower bass.

The JVC's don't separate the different frequencies very well either, making complex music passages kind of muddled.  Soundstage is really limited, without width or depth.  Midrange and upper frequencies sound good, and wind and string instruments have nice tone and timbre, although transients (cimballs, drum plates, etc.) sound really mediocre.

Then there's the amps difference.  I'm not qualified to judge these on a technical level, but I'm sure my current (4 amplification stages for a Bi-amping/Bi-frequencies design) SS integrated is not at the audiophile level (it's hard to tell where the speakers limitations end and where the amp's limitations start though).

I'll let you all know how it works out.
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« Last Edit: 04/17/12 at 16:36:17 by Fireblade »  

Laptop-Foobar2K-ASIO Direct//WD 2.0Tb HDD//Audio Gd USB cable//Audio Gd NFB 3 (2014) DAC//Decware Silver Ref IC's//Decware Mini Torii SE//Kimber Kable spkr cbls//Decware DM945's//Velodyne DLS 3500//BJC SUB Cbls//Tripp Lite 500 Isolation Trnsf.//Jellyfish Pwr Cord
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