Welcome, Guest. Please Login or Register
Decware Audio Forums
10/02/14 at 13:43:33


Pages: 1 ... 69 70 71 72 73 74
Send Topic Print
The MYSTERY AMP ! (Read 146584 times)
Leigh
Verified Member
**




Posts: 1
Re: The MYSTERY AMP !
Reply #1050 - 04/11/14 at 21:45:04
 
Hello, all. I'm taking the plunge with the Mystery Amp! I've read through this entire thread. I tip my hat to those brave souls who jumped in the water before me!

Over the years I've upgraded my speakers, digital front end, and, last year, turntable/phono preamp... and all of it has been amplified by a heavily modified Dynaco ST-70. By "heavily modified" I mean all that is original is the chassis and transformers! It's been a fun DIY project and it still performs surprisingly well, with lots of magic. But.... it's probably the weak link. Even though I have done the power supply upgrade, and a decent driver board upgrade (Triode Electronics) I just itch for something a little more... pure, with a bit more clean power.

I've been drooling over Decware amps (and others) for a while now. But, I wanted more power than the Torii and the dual monos are just too far outside of my budget. So when I recently discovered this new amp it just hit all the right buttons. Hoping it's the last one I ever buy! What specifically drew me to this amp: (1) Dual mono design. Just makes good sense (2) Being able to use a variety of power tubes... I have lots of 6CA7/KT77/EL34 types lying around. I've never heard 6L6 type tubes in operation, so this will be fun (3) An intelligent biasing system. This is something I've always wanted. And those analog meters... drool (I'm also a ham radio nerd and have done radio/audio stuff so meters make me happy). (4) I am intrigued by the lack of global negative feedback. I don't see the existence or lack of global negative feedback to be a black and white issue, but I have a sneaky suspicion that a lot of the good things people are hearing with this amp has to do with a type of sonic purity in the signal path that may reflect a lack of global negative feedback. So cool beans. (5) Made in the US. This is not a slam on other countries or a jingoistic rah rah thing, it's just that so little stuff is made here and I like to support local(ish) businesses when I can. Oh, (6) It looks fan-f***ing-tastic. I'm going with the maple frame - a brighter happier look Smiley. The only other upgrade I chose was the stepped attenuator - I just will feel more at ease with that.

So now that I'm officially on the build waiting list I thought I'd chime in and say hi. I'll be sure to share my impressions when that lovely heavy package makes its way to my doorstep in a couple months.
Back to top
 
 
  IP Logged
Lonely Raven
Seasoned Member
****


Jack of all Trades,
Master of None

Posts: 1400
Re: The MYSTERY AMP !
Reply #1051 - 04/11/14 at 21:51:25
 

Congrats on the Purchase!

I've played with a few Dynaco amps over the years, and was tempted to build one from scratch using the Triode parts (they are Chicago based). The ZMA is for sure in a different league than the Dynaco stuff. Your ST-70 will be quickly relegated to your "second system" LOL

I look forward to hearing what you think of the Mystery Amp when it arrives. I swear every 100 hours the amp bumps up a notch - so you'll have a lot to look forward to.
Back to top
 
 
WWW Lonely Raven   IP Logged
Dave1210
Seasoned Member
****




Posts: 375
Re: The MYSTERY AMP !
Reply #1052 - 04/12/14 at 14:57:31
 
I did a little searching on negative feedback a couple weeks ago after a listening session and below is some information I found. NOTE: I pulled these references from the internet so they must be fact.

Excerpts from an interview with Charlie Hansen from Ayre (Ayre Audio only produces solid state amplifiers, so this isn't specific to tubes)

http://www.ayre.com/insights/APJ10_Reprint_Ayre.pdf

Feedback also happens to improve the measurable characteristics of amplifier circuits by increasing the bandwidth, reducing the distortion (at least for steady-state signals), and lowering the output impedance. And this is why its use became so universal in audio circuits. For decades, it was assumed that there was a direct correlation between measurements and sound quality. But there is something about feedback that we can't really measure that seems to have a detrimental effect on the sound quality of real musical instruments. It seems to be related to time domain performance.

Time domain performance? Can you elaborate?
Well, the simplest way to think about this is that feedback cannot respond to an error until after the error has occurred. And this correlates pretty well with what we hear. Compared to a zero-feedback design, adding feedback seems to overemphasize the leading edge of transients. This can give a more "spectacular" sound in the hi-fi sense, but it is less musically natural than a zero-feedback design. And this sonic "thumbprint" seems to exist under a wide variety of conditions. On the other hand, a zero-feedback design becomes very chameleon-like from a sonic standpoint. In my experience, the zero-feedback designs will "get out of the way" of the music with a wide variety of source material. And with our designs there isn't any reason to use feedback.

The below reference is from an article comparing SS vs. Tube, but there was some discussion on feedback:

http://spectrum.ieee.org/consumer-electronics/audiovideo/the-cool-sound-of-tubes...

In Atwood's opinion, "Some of the differences in the audio qualities between tubes and transistors have to do with the inherent physical properties of the devices and with the circuit topologies and components used with each type of device. There is no way around it: linear [triode] vacuum tubes have lower overall distortion than bipolar transistors or FETs, and the distortion products are primarily lower-order...the clipping characteristic of tubes is actually not much softer than transistors, but feedback tends to 'square-up' the clipping. Thus, the heavy feedback in most solid-state designs gives them worse overload performance.

"A low- or no-feedback design can be driven harder without audible distortion," Atwood continued. "High feedback also can lead to transient intermodulation distortion (TIM), caused by clipping or slew-rate limiting within the feedback loop." See following table for a comparison of the attributes of tubes and transistors in audio applications."

Speaking about solid-state designs, Whitlock asserted that they † †"...depend on huge amounts of negative feedback to 'fix everything', including crossover distortion. Op amps commonly have open-loop THD in the 20 percent to 70 percent range. Stabilization generally requires open-loop gain to fall at 6 dB per octave. This means that, for ultrasonic input signals, the op amp has little gain margin to fix its own distortion. The ultrasonic signals, along with distortion products, are fed to the next stage for further distortion and intermodulation. This intermodulation creates audible, but non-harmonically related, artifacts which contaminate the noise floor and mask many subtle features of the music."

Nelson Pass did some simple distortion experiments, see the article for additional detail †https://passlabs.com/articles/audio-distortion-and-feedback

Negative feedback can reduce the total quantity of distortion, but it adds new components on its own, and tempts the designer to use more cascaded gain stages in search of better numbers, accompanied by greater feedback frequency stability issues. The resulting complexity creates distortion which is unlike the simple harmonics associated with musical instruments, and we see that these complex waves can gather to create the occasional tsunami of distortion, peaking at values far above those imagined by the distortion specifications.
Back to top
 
« Last Edit: 04/12/14 at 19:48:10 by Dave1210 »  
  IP Logged
Steve Deckert
Administrator
*****


If the 1st watt
sucks why continue?

Posts: 2417
Re: The MYSTERY AMP !
Reply #1053 - 04/13/14 at 05:39:01
 
Smile...

In the very early pre Decware days during the 17 years between my first wife and my second wife, I did my serious listening every night from 10:45 P.M. to 2:45 A.M. †During this time, my corner horns were my primary reference speaker and were on either side of a 6 foot opening into another room of equal size which opened up to a third room of equal size. The speakers were a mere 13 feet apart putting me at 6 feet back due to the 45 degree toe in. Of course with an opening in front of me with some 30 feet of optical depth I certainly didn't feel like I was sitting that close.

Just to mess with my brain, I put a baby grand piano in the second room behind the speakers... that was fun.  It was especially fun when listening to piano music.  The typical recording put the piano right where it actually sat.  Good stuff Wink

I learned about negative feedback in this place.

The first time I lifted the feedback on a tube amp in this room I almost pissed my pants. You see the stereotypical soundstage I was used to went 6 feet behind the speakers (on a good night). With the feedback removed the sound stage suddenly exploded back into the back wall of the third room. That was 30 some physical feet but it sounded like 90. †

This illusion became an obsession of mine that lasted for several years where the depth of the sound stage became the ruler by which one amplifier's stripes were measured against another. I can remember many times when two amplifiers were tried and... same frequency balance, same bass, same dynamics, same sound but one went back to the third room and one didn't. †Winner!

It doesn't really take a lot of math to understand that it takes a finite amount of time for the signal to pass through an amplifier and during that process it gets delayed more at some frequencies than others aka phase shift. †

So if you take a signal from the output of the amplifier that is delayed and no longer in-phase relative to the input at most of it's frequencies and feed it back into the input... the end result is smeared time and smeared phase. It's so smeared in fact that the low level ambient information that contains the sound stage depth cues is completely destroyed. Add to the casualty list: transparency, openness, presence and micro detail and of course ambience. †

Taking the momentum of this thought a bit further, imagine taking the tube circuit poisoned with negative feedback and exchange it for solid state with 10 times as many parts and 4 to 10 times MORE feedback. hmmm yummy. Then invent CD's. Take away the last hope and make us listen to our miserable crap on an equally miserable format. After all, since CD is missing some 40 percent of the music, and solid state amplifiers gross amounts of negative feedback kill about that same amount, no one will even notice.

Frankly I was mortified. †Decware was born from that disgust.

On a happier note, despite the corner horns having perhaps the best bass ever... and extension to the mid 20's... †Imagine the following: †The house was over 150 years old. There was a basement. I build a concrete horn in the basement that wrapped around the furnace. †It has a throat that was 3 inches x 48 inches and a mouth that was 10 feet by 48 inches with a total length of 18 feet. The wall thickness of the horn was 4 inches on one side and infinity on the other being underground. I estimate it weighed over 3000 lbs for just one side wall of the horn. †(grin)

With a single 12 inch woofer I cracked my basement in 72 places in on the very first test. The bass from this sub when you were upstairs in the listening chair was so fast you perceived the kick drum coming out of your chest.... agh the good old days... †when i was still crazy.

Happy listening!

Back to top
 
« Last Edit: 04/13/14 at 06:01:53 by Steve Deckert »  
WWW   IP Logged
Lonely Raven
Seasoned Member
****


Jack of all Trades,
Master of None

Posts: 1400
Re: The MYSTERY AMP !
Reply #1054 - 04/13/14 at 15:07:13
 

I remember that sub-woofer you build out of the curvature of your basement. It was practically a bucket list item for me to sit inside it when I first went to visit you at the old place. I never did get to hear it though.

That's great info on the negative feedback. The reasoning behind it makes sense, but I've heard time and time again how if the electricity is moving almost at the speed of light, it would be impossible for us to perceive the difference of time in the negative feedback. But then time and time again, I find amps that don't smear the micro-detail and timing (and digital with the least jitter) always seems more life like and those ambiance cues pop out.

I think there is still a lot about sound and how the brain processes it that we don't know, or that scientists may know, but haven't explored because they really don't see a reason too. (or how to make money off of the research)
Back to top
 
 
WWW Lonely Raven   IP Logged
stone_of_tone
Seasoned Member
****


Listen Often/Listen
Deep

Posts: 831
Re: The MYSTERY AMP !
Reply #1055 - 04/16/14 at 17:31:23
 
No doubt... . I can't enjoy a 75 watt per channel push pull Amp like the Audio Research because of the Negative Feedback in the VSi75.
http://www.audioresearch.com/VSi75.html
....the negative feedback and not Steve's Topology. I also did my best to enjoy this one.......
http://www.audioresearch.com/Reference75.html

....nope....the CSP3 & ZMA win... . ...not about the money either...if the AR stuff was better (either one)...I would have bought it. Being able to also dial in the Voltage output to my ZMA for my Anthony Gallo Reference 3.1's...is a shat your pants factor too.
Back to top
 
« Last Edit: 04/16/14 at 17:34:31 by stone_of_tone »  

Sony as Transport
Illuminati D-60
Audio Alchemy DTI-Pro
Audio Magic Mystic Reference I2S
Audio Alchemy DDE 3.0
Kimber Select 1030
Zen Select #76
Kimber Select 3033
Polk Audio LS-90
Tri-config/TipToes & Vibropods underneath Speakers
360 degree Rm Treats
  IP Logged
Alaska Dave
Verified Member
**




Posts: 1
Re: The MYSTERY AMP !
Reply #1056 - 04/17/14 at 08:07:16
 
Hello, Folks.  Iím new to Decware, and to this forum.  Since my Mystery Amplifier shipped today, Iím thinking itís a good time to introduce myself.  My handle is Alaska Dave, out of Juneau, Alaska.

Iíve been in the audio game seriously something over 20 years.  Like many of you, Iím dedicated to the purest, most natural and present sound I can get.  I like to do a major upgrade to my system about once per year.  Since 2000, Iíve been using an Art Audio Diavolo amplifier (13 watts, SET, Class A, no negative feedback, KR 842 VHD output tubes).  This is a superb single-ended amplifier, but is showing its age, so Iíve been looking toward a new amp for quite a while.  End of last year I was trying to narrow the field, and the Mystery amp came up on the radar.  Itís apparent potential and promise intrigued me, and after a couple of conversations with Steve Deckert, I placed the order in January.  Frankly, the review of the Torii Mk III in Tone Audio gave me confidence, too.  So the waiting game is almost over.

My speakers are Marten Miles 5s, Accuton drivers, 90 dB, new last spring.  I had the Miles 3s for seven years prior, and the 13-watt Diavolo drove them easily (substantial power supply there, too).  The speakers are highly resolving, accurate, and musical, which is why I upgraded to the new model.  My source is an EAR Acute 3 DAC/CD player with tube output stage, with hi-res music files pending, soon as I figure that out.  Audience aR6-TSS power conditioner and Acoustic System Liveline cables.

Actually, besides being a dedicated audio nut, Iím a very small, out-of-home, two-channel, audio dealer in Juneau.  I keep up with the market very closely; Iíve attended all but one of the 10 RMAF shows and several CES and other shows.  And Iím retired, which is a wonderful thing!

This Forum has been impressive as to the breadth and depth of knowledge, and for its dedication to the art.  I look forward to beginning the Mystery amp experience, and to sharing it with all of you.  And let me know if youíre ever in the neighborhood!  Good listening!

Back to top
 
 
  IP Logged
Lon
Seasoned Member
****


"Love without
guts is
worthless!"
Philip K. D*ck

Posts: 7584
Re: The MYSTERY AMP !
Reply #1057 - 04/17/14 at 10:53:40
 
Welcome Dave! I am sure you are going to be impressed with the Mystery Amp!
Back to top
 
 

Decware:ERR,HR-1,ZP3,CSP2+,Torii Mk III,PS Audio PWT+DS,PowerBases,PPP,AC-12 pcs, Denon DBP-A100, Denon DCD-A100,Rega RP3 +TTPSU,white belt+Exact2, VooDoo Cable:Evo,Ultra Linear, Iso-PodMapleshade:Double Heiix Plus.Samsonv2+v3 +4" platforms,Herbie's Iso-Cup
  IP Logged
Lonely Raven
Seasoned Member
****


Jack of all Trades,
Master of None

Posts: 1400
Re: The MYSTERY AMP !
Reply #1058 - 04/17/14 at 12:44:23
 
Hey Dave! It's good to see you posting here!

With the experience you have in two channel audio, I really look forward to your reports on the Zen Mystery Amp. While I think I have a decent ear for listening, I don't have the experience many of you have to (physically or mentally) compare the ZMA to other modern amps.

Congrats on the imminent arrival of your new amp!

Just give it about 100 hours before you really give it a listen. I swear it seems to step up a notch about every 100, and that first step for me was about 125 hours.
Back to top
 
« Last Edit: 04/17/14 at 15:20:55 by Lonely Raven »  
WWW Lonely Raven   IP Logged
stone_of_tone
Seasoned Member
****


Listen Often/Listen
Deep

Posts: 831
Re: The MYSTERY AMP !
Reply #1059 - 04/17/14 at 15:17:02
 
Welcome Dave!

I am glad to read you have great Speakers & Cables! You will get to hear what the ZMA can really do...(like me). I use a pair of Gallo Acoustic Reference 3.1's currently an Kimber Select 1030 IC an Select 3035 Speaker Cables.

I remember a gentlemen at the 2005 DecFest that was a Dealer for Art Audio...and he was there to hear if Decware was hype. He left knowing these Amps can compete with Art Audio.

I am very pleased with my ZMA & CSP3 combo! †I am now looking at your choice in Speakers! I am always out for improvement... .
Back to top
 
« Last Edit: 04/17/14 at 15:17:27 by stone_of_tone »  

Sony as Transport
Illuminati D-60
Audio Alchemy DTI-Pro
Audio Magic Mystic Reference I2S
Audio Alchemy DDE 3.0
Kimber Select 1030
Zen Select #76
Kimber Select 3033
Polk Audio LS-90
Tri-config/TipToes & Vibropods underneath Speakers
360 degree Rm Treats
  IP Logged
Doorman
Seasoned Member
****


"pouring from
the empty into the
void"

Posts: 424
Re: The MYSTERY AMP !
Reply #1060 - 04/17/14 at 15:23:57
 
Can you say more about your current amp "showing it's age" ?
(- not sure what that means. I'd have thought an amp like that would
perform well for many years)

Sounds like the rest of your system will really compliment your ZMA !
Back to top
 
 

Decware SE34I w/ CCE mod, ZCD, Heybrook/Linn/Clearaudio, Hagerman,
Goertz/Wireworld/cat-5/MarkAudio Alpair 10.2 drivers
(eN) in DIY Mar-Ken cabs
  IP Logged
stone_of_tone
Seasoned Member
****


Listen Often/Listen
Deep

Posts: 831
Re: The MYSTERY AMP !
Reply #1061 - 04/20/14 at 16:53:36
 
....Morning Jam Session with the CSP3 an ZMA combo. I am pounding the ZMA right now at 88db SPL...and peaks of 92! The beautiful tube compression with no ear fatigue an such clarity of focus! †

Cheeeeeeeers, an Happy Spring! †

402 hours on the ZMA as I type...an 42 on the CSP3...+/- only .5 hours.
Back to top
 
« Last Edit: 04/20/14 at 16:55:24 by stone_of_tone »  

Sony as Transport
Illuminati D-60
Audio Alchemy DTI-Pro
Audio Magic Mystic Reference I2S
Audio Alchemy DDE 3.0
Kimber Select 1030
Zen Select #76
Kimber Select 3033
Polk Audio LS-90
Tri-config/TipToes & Vibropods underneath Speakers
360 degree Rm Treats
  IP Logged
Lonely Raven
Seasoned Member
****


Jack of all Trades,
Master of None

Posts: 1400
Re: The MYSTERY AMP !
Reply #1062 - 04/20/14 at 18:13:41
 

Stone, do you feel your ZMA is developing anymore? I'm not far behind you in hours, and I'm feeling like mines starting to plateau (if it hasn't already).
Back to top
 
 
WWW Lonely Raven   IP Logged
lLance
Verified Member
**




Posts: 14
Re: The MYSTERY AMP !
Reply #1063 - 04/20/14 at 21:32:48
 
Has anyone here done any tube rolling? I just tried some cryoed KT88 Gold Lion tubes. I liked the sound but didn't continue because I could not adjust the bias to the 50 mark. It seems I'm bottomed out on my adjustment at almost 70 on gauges. Thought I would check with you guys while I'm waiting for a reply from Steve.

Lance
Back to top
 
 

ZMA, Tori MK3, Audible Illusions M3B pre, NAD M51 DAC, VPI Scout 1.1 & Soundsmith Zepher Cart, Janszen zA2.1 Speakers, Berkeley Audio Alpha USB, PS Audio P10, Win 8 & J River app, Audioquest Sky XLR, Triode Wire Labs #7 & Black Sands Z1 PC, VooDoo AES/
  IP Logged
Lonely Raven
Seasoned Member
****


Jack of all Trades,
Master of None

Posts: 1400
Re: The MYSTERY AMP !
Reply #1064 - 04/20/14 at 22:45:45
 

Steve has a specific bias window set for safety reasons. If you've got the bias knobs cranked full right (which makes the needle go left) and you aren't anywhere in range, then it's good you pulled the plug on that. I believe Steve said you could pretty much use any of the common output tubes you wanted, as long as you're able to bias it at 60ma or less. Any more than that would strain the power transformers and run them to an early demise.
Back to top
 
 
WWW Lonely Raven   IP Logged
Pages: 1 ... 69 70 71 72 73 74
Send Topic Print