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12/19/14 at 04:40:11


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Welcome to the Mystery Amp Support Forum! (Read 4401 times)
Brian
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Re: Welcome to the Mystery Amp Support Forum!
Reply #15 - 06/17/14 at 06:37:18
 
RickVee asked:
"I suppose that a good tube preamp with XLR and RCA inputs might be that much better.  Any ideas?"

Hello Rick.
Do either your phono amp or your BluRay player have gain controls? Do you know how much is the maximum voltage they can put out?  Do you know the output impedance of either device?

It seems to me that there are three purposes for a preamp. Adjust voltage, impedance match a source to your power amp, convenience as a switch box.  

I ask the panel, am I right in thinking Rick has impedance matching covered now that he has the XLR transformers on his power amp inputs?

As for voltage adjustment, this is a nice way to control the sound, but if you already have gain controls on both of your sources then I don't see that an additional gain stage can help your sound, unless one of your sources turned up to full volume is still under volted for it's best possible sound.  

- Brian
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RickVee
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Re: Welcome to the Mystery Amp Support Forum!
Reply #16 - 06/17/14 at 19:01:24
 
Hello Brian,

Thanks for raising these issues.  My OPPO BluRay has an output voltage of 2.1 Vrms RCA, and 4.2 Vrms XLR, with an output impedance of 100 ohms.  It also has a gain control.

The phono stage is an old Creek OBH 8, with an output of 250 mV, and an output impedance of 750 Ohms.  It has no gain control.  I plan to replace it after I recover from the purchase of speakers, the BluRay, and the ZMA.

With the addition of a better phono preamp, I probably will not need a line preamp.

Rick
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stone_of_tone
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Re: Welcome to the Mystery Amp Support Forum!
Reply #17 - 06/21/14 at 04:44:54
 
Having some fun tomorrow night....pitting the SE84CS against the ZMA with an without my CSP3......... .

I was able to switch her in early today....and as much as I like my ZMA's power an lower end and head room... . I still love my SE84CS! The lit from within qualities of it...do it for me. I have the CSP3 dialed into it nicely. I am going to keep it in for awhile then put the ZMA back in an then the Super Zen CKC.  Musical - musical and musical!   -Stone
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« Last Edit: 06/21/14 at 21:26:21 by stone_of_tone »  

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Brian
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Re: Welcome to the Mystery Amp Support Forum!
Reply #18 - 06/21/14 at 22:18:56
 
Hi Rick,
I think you are right. It sounds like OPPO is doing all a preamp would do.  
One of the Decware preamps goes to a maximum of 30 Volts out, so a more driven sound could be had if it were desired.
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RickVee
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Re: Welcome to the Mystery Amp Support Forum!
Reply #19 - 06/30/14 at 18:34:11
 
I was just notified that my ZMA has shipped, so I just have to wait for it to make the long (but not perilous) journey from Peoria to Albuquerque.  More to come ....
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Lonely Raven
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Re: Welcome to the Mystery Amp Support Forum!
Reply #20 - 07/01/14 at 04:52:25
 

Congrats! I'm sure you'll like it, especially with the Oppo!
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stone_of_tone
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Reply #21 - 07/02/14 at 14:20:22
 
Cool Rick! You're just days away from hearing this ZMA masterpiece.

I put the ZMA back in (on Saturday) after doing a tour of my SE84CS an CKC. Ohhh, I love (an missed) the ZMA in the System with my CSP3.... .
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jsm71
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Reply #22 - 07/03/14 at 17:13:03
 
Guys, I was wondering about the KT120s as well.  I don't understand tubes that well.  Would the 120s require more current above the 60 MA "limit" to sound correct?

A friend of mine has fallen in love (on paper) with the Quicksilver Silver 88 monos because they produce 80 watts/ch and can run the 120s as well as the new KT150s.  I guess I need to understand what that amp does so differently to be indifferent on the tube choices.  Are the stock KT88s that it uses that different of a tube over the KT66s?  Are all these KT tubes basically the same with different current requirements or are there significant differences?  

Just trying to get some education here.  I do love the sound of my ZMA, but if I could urge a tad more power just with different tubes ...

Scott
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stone_of_tone
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Reply #23 - 07/03/14 at 18:45:46
 
Someone else I'm sure will chime in here. Maybe Steve will too.
With negative feedback in the Quick Silver you can drive the hell out of it with power.... .

But, in regards to "...if I could urge a tad more power ...through the ZMA..."

This is the age old question? More power though...LESS FIDELITY.

I could own the the 88's or
http://www.vac-amps.com/productPages/Phi200.html

.....but I won't give up the Fidelity of Steve's Amps for the Power.

My CSP3 with Jupiter Bee's wax caps...pushes definition quite well...that is a great option...I love mine with ZMA (NO negative feedback an clean power design).

Plus, this begs the question. How loud do you listen? My ZMA with CSP3, when I want to, can do 88db SPL peaks....with fidelity that beats said above Amps.  
The CSP3 is a Transparent ass kicker of Definition an Weight through my ZMA.
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« Last Edit: 07/03/14 at 19:13:09 by stone_of_tone »  

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Lonely Raven
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Re: Welcome to the Mystery Amp Support Forum!
Reply #24 - 07/04/14 at 03:06:20
 
Quote:
Guys, I was wondering about the KT120s as well.  I don't understand tubes that well.  Would the 120s require more current above the 60 MA "limit" to sound correct?

A friend of mine has fallen in love (on paper) with the Quicksilver Silver 88 monos because they produce 80 watts/ch and can run the 120s as well as the new KT150s.  I guess I need to understand what that amp does so differently to be indifferent on the tube choices.  Are the stock KT88s that it uses that different of a tube over the KT66s?  Are all these KT tubes basically the same with different current requirements or are there significant differences?  


I'm no expert, and most of my experience is with guitar amps, but I have read up a bit and built a few (kit) amps before - so I have a basic understanding.

KT66 and KT88 tubes have been around for ages, they are part of the Kinkless Tetrode family (where the KT comes from) - they are designed similarly to the 6L6/EL34 audio tubes, but designed to handle more current and therefore can output more power.

The KT120 and KT150 are modern interpretations of those classic tubes, bigger, more output. Not necessarily *better* (not saying worse either - just bigger, more output). These bigger tubes simply require more current, and unless the amp is designed to supply this current required the least that could happen is the tube is starved and sounds cold and weak, at worst it would cook the amp because they are trying to draw too much juice.

ZMA is built around the more classic tubes, and just doesn't have the juice to power those bigger tubes like the fancy KT150.

I have no experience with these big tubes, and they could sound awesome, but I feel the design of the amp is really what makes or breaks the sound, not what tubes you pop in or how many watts they produce.
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jsm71
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Reply #25 - 07/04/14 at 14:56:30
 
Thanks for the input.  That pretty much matches what I assumed.  I thought negative feedback had to be in there somewhere as a crutch.  Usually the designers who use feedback don't talk about it on their web pages unless it is zero.

Quote:
Plus, this begs the question. How loud do you listen?


For me the ZMA as designed gives me plenty of volume.  It can go louder without any apparent negative impact to fidelity than I care to listen to.  My max volume in my small room is at about 80dB.  The room is very quiet so 80 seems loud.  I pushed it once with no bad effects up to about 90db but that was way too much for me.  Big impact sounds happen all the time that likely go above 90dB but I don't count those.  The amp is doing just fine and my JansZens are only 87dB.  The only interest in more power would be if I had a bigger room when I retire and need more output.  Like most of Steve's customers I won't give up fidelity to achieve that however.
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« Last Edit: 07/04/14 at 15:00:49 by jsm71 »  
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kana813
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Re: Welcome to the Mystery Amp Support Forum!
Reply #26 - 07/17/14 at 19:59:15
 
"I have no experience with these big tubes, and they could sound awesome, but I feel the design of the amp is really what makes or breaks the sound, not what tubes you pop in or how many watts they produce."

I've read a number of reports that the KT-150s are a big improvement over the KT-120s from ARC REF 75 owners.

Can the ZMA be upgraded to run these tubes?

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RickVee
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Reply #27 - 07/17/14 at 22:49:55
 
Hi, all --
The monsoon season has arrived in NM, and so has my ZMA (10 days ago).  We had an inch of rain last night (nothing for the eastern half of the USA), but as much as we have had for the first half of the year.

The ZMA is all that I expected and a worthy replacement for my old Nakamichi receiver.  Full, unadorned sound no matter whether I am playing Palestrina on BluRay audio, or Pink Floyd on my new vinyl repressing.  Despite having no controls on my phono pre, the ZMA has enough volume (92 dB speakers) on "Dark Side of the Moon" to drive my 90 lb. pitbull, Satchel, to the other end of the house (wife not home of course).

Even broadcast and satellite radio, with my NAD M4 tuner connected directly via rca, is superior.  As everything burns in nicely, I have one naive question for the group.  Since the amp has both rca and balanced inputs, not switchable, only one at a time, can I leave the cables in place, so long as only one source is powered on?  I ask because the maker of my balanced cables says they are temperamental, and do not like to be moved around, and will be cranky for a day or so after being replugged in.  This sounds a bit "barmy" to me, but ... any opinions/info would be appreciated.
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Lonely Raven
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Re: Welcome to the Mystery Amp Support Forum!
Reply #28 - 07/17/14 at 22:52:09
 
Quote:
I've read a number of reports that the KT-150s are a big improvement over the KT-120s from ARC REF 75 owners.

Can the ZMA be upgraded to run these tubes?


That would require at very least a whole new power transformer setup, and probably a power supply circuit adjustment all down the line.

I'd ask (call) Steve, but that's practically designing a new amp at that point, as any major changes like that, the amp would need to be revoiced (IMHO)
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« Last Edit: 07/17/14 at 22:53:25 by Lonely Raven »  
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Lonely Raven
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Re: Welcome to the Mystery Amp Support Forum!
Reply #29 - 07/17/14 at 22:56:11
 
Edited:
Even broadcast and satellite radio, with my NAD M4 tuner connected directly via rca, is superior.  As everything burns in nicely, I have one naive question for the group.  Since the amp has both rca and balanced inputs, not switchable, only one at a time, can I leave the cables in place, so long as only one source is powered on?  I ask because the maker of my balanced cables says they are temperamental, and do not like to be moved around, and will be cranky for a day or so after being replugged in.  This sounds a bit "barmy" to me, but ... any opinions/info would be appreciated.


The RCA inputs supersede the XLR inputs when both are plugged in. I think Steve said he would unplug the RCA before using the XLR. I'd double check with him, as I could be remembering that wrong.

Once I went XLR, I never looked back - such a great improvement with the Oppo and Reel to Reel. The ZMA really likes that voltage. But if you had to swap between the two regularly, maybe it's time to look into a preamp?
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« Last Edit: 07/17/14 at 22:58:16 by Lonely Raven »  
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