Steve does tend to have a bit of marketing flourish, and is well known for it. I know some people simply wont take him or his products seriously because of it, and some flat out *hate* him saying he's pedaling snake oil because his descriptions are a bit out there, or numbers are rounded up or whatever.

I have asked him about the wattage of the ZMA since I was pretty sure you couldn't do class A 40watts, and have gotten different answers depending on what he feels like divulging and his mood. I get the feeling that this is just a case of rounding to the nearest 10 so people are less dismissive of the amp.

I see these guys at the link also taking his marketing a bit too literally. Steve knows the laws of physics quite well, and when he says the regulator tube has no heat, he's speaking relatively; dropping resistors do get hot, and compared to other tubes the regulator tubes really don't get hot...so from the point of view of generating enough heat to effect *anything* on the amp, yeah, I get what he's saying.  

I'm betting if these solder slingers actually saw what he was doing, saw a schematic or poked around in a ZMA with a probe they'd probably nod knowingly, wax on about how they'd do things differently, and maybe even offer some comments on how "pedestrian" his work is (believe me, I've heard this before from otherwise very knowledgeable EEs and amp builders alike). The fact is Steve tends to do things outside the norm, and most amp builders are just doing the same things, the same ways, with the same circuits since the 1940s straight from the military manuals. Part of what I love about Steve's work is he does a lot of "what if I did....". He's willing to experiment and fail, try things that most don't, and probably some things he shouldn't. LOL

I figure Steve's probably bending some numbers here and there to make things look more attractive to the guys who judge everything on specs...the "math guys" who don't even give gear a listen unless it looks good on paper. (shrug) I've learned to listen and trust my ears. I really don't care that my ZMA is probably 33watts rather than 40watts, though even I've rolled my eyes at some of his flourishes, it really just reminds me of how passionate he is about all this. Besides, I'd say he's a bit more successful than those solder slingers in the forums; the proof is in the puddin'.

Lastly, as for the caps, I don't think there is a worry at all. It's silly speculation, and the caps would probably wear out from use (power cycling) long before the heat of the power tubes does anything to them...hell, the big caps appear to be wrapped in a heat shrink plastic of some sort...if that stuff hasn't melted by the heat of the tubes, I can't imagine how the heat is shortening the life of the caps!!  Also, my ZMA has the big red caps which were Milspec NOS parts intended for use in a nuclear power plant....I'm pretty sure they are up to the task of handling a little heat from the power tubes!  ::)

Two years and nine months on mine. It never gets old to say: "you will need to pry my ZMA from my cold dead hands."

It took me 37 years to arrive at this great Amp. The audio fools can pontificate all they want to. I and I bet Steve just chuckles.

Good call out Archie and insight LR.

Steve, thank you for your ART.

Jeff,

You examples help put some perspective on things.  I guess I was looking for a reality check as well as information on what the "Class" designations mean.  Also, I'm interested in heading off any problems that may only come with time.  (The disconnects between those forum critics and our experience with our Decware gear reminds me of dealing with my ex-wife!   )

I doubt it too. You enjoying the tubes Archie?

Thanks for sharing. I like them too. The truth of the matter is that I have three sets of tubes I've been popping in and out this year and with the flexibility of the Torii Mk III I can make either of them really sing in the amp and I can live with any of them. (TAD KT66, JJ 6CA7, and these). All great sound-makers!

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I might even try those myself, when I have the funds. I still need to send Lon his 6P3S-E back. I could use both the JJ and the 6P3S-E in my guitar amps, so even if they don't get use in the ZMA, they are still useful to me.  :)

I'm trying out a '40s vintage set of 807 tubes in the ZMA right now. going to give them a few more hours to burn in, then compare Lon's 6P3S-E, and my old (stock) KT66 one late night (especially now that the house is so quiet with no pets and no girlfriend)

Why, yes Virginia, there is such a thing as class-a push-pull amplifiers. You can find an excellent description here http://www.aikenamps.com/index.php/the-last-word-on-class-a
research also sez 2 kt66 tubes operating in push-pull ultra-linear can produce 50 watts. All electrical failures are mechanical in nature,so can the caps fail, of course, but that doesn't mean they are going to fail from the meager amount of heat coming from an OA3. And as far as class is concerned, Steve has it in spades, those guys over at diy, not so much.

Good question LR? .....where does he see the part about KT66 being..... .

Anyway, to further comment on your well put response LR, " I've learned to listen and trust my ears. I really don't care that my ZMA is probably 33watts rather than 40watts (38 watts)."  

Ditto for me too and if it crosses into AB when I push her....don't care either. The ZMA is the best Amp I have heard (in 40 years/got into Audio when I was 13) when I push her to compression and incomparable under it.

Jeff1, great points too. You did your homework and chose the ZMA. I would love to hear your Legacy Sigs with it.

PS~reading the Aiken paper ...last word in class A.......confirms how important the phase splitter tubes are! The Telefunken E88CC/6922's are expensive....but a damn well worth it upgrade to your ZMA, IMHO. A pair of these in the PSplit's....really lets your Input tubes shine! For me it is: Mullard E188CC's and Ediswan's.   ......Tungsrams too.

One time when I encountered someone giving me some grief about Decware amps I showed them this review. They knew Tone Audio and this had them scratching their heads and looking into Decware with a different eye.

http://www.tonepublications.com/review/decware-zen-mystery-amp/

I like and have used Lon's approach a few times with a few ''audiophiles'' and after reading Jeff's review of the ZMA asking if they could come over an listen to our little system. All have been impressed by Decware and how it gets OUT of the way of the music and you just get DRAWN in. Magic boxes by the Zen Master. Happy listening, Chris.

Hi Archie,

Sorry I didn’t see this thread sooner! To the difference between Class A or Class AB is well written in the article Denizen posted written by Randall Aiken.

As Lonely Raven illuminates there are long time Decware bashers, it goes with the territory. It’s not uncommon for “experts” on DIY forums to puff up their egos by bashing the real deal, which is the guys who have successfully built and shipped over 6000 amplifiers in the past 20 years with a lifetime warranty, all still in service.  

The big caps will not deteriorate from excessive heat from the output tubes, that’s the kind of thing that happens to DIY amplifiers that are not well engineered.  

I’m pleased to hear you’re still enjoying your ZMA after 2 1/2 years. Should be starting to get warmed up and sounding pretty good by now

Lonely Raven,

If you look at a data sheet for the KT66 (http://www.r-type.org/pdfs/kt66.pdf) you will see in Push-Pull Pentode connection typical operation is 30 watts for the pair of tubes. If you look at the same operation with fixed bias instead of a cathode resistor, your power increases to 50 watts. That’s in class AB1 operation. If you were to employee an ultra-linear output stage the power would increase significantly further. The ZMA is both fixed bias and ultra-linear.

You have asked about the wattage of the ZMA from time to time and if you got different answers it would have been the context of the question, not what I feel like divulging or my mood. Probably looks that way on my face when asked though, because I’m trying to decide how simple or complex to make the answer. For example, a simple answer would be 38/40 watts. A more truthful answer would be that it depends on the voltage at the wall outlet and it’s effect on the B+ voltage of the amplifier as well as the bias supply. All of this will determine what the tubes bias up at relative to the available plate voltage which effects power. That is to say nothing about the gain of both the input tubes and output tubes. For example, the input tube may have a gain anywhere between 25 and 35. The output tubes also test with a gain figure anywhere between 15 and 30 when measured at 400V and -48v bias.

Happen to have a set of 25 input tubes and 15 output tubes and you’re going to get less than 38 watts. Put in a set of 35 input tubes and 25 output tubes and your going to have over 38 watts. This is of course measured into a dummy resistor not a complex impedance like a loudspeaker. Since dummy resistors make no sound, no audiophiles to date have used them for speakers so the power ratings are largely misleading. I know that into a loudspeaker most of our amplifiers actually put out significantly more power instead of less.  …the more complex answer.

Regarding class A operation I am guilty of being one who thinks that if an amplifier is biased close enough to class A that it maintains class A operation through the first several watts it is basically a class A amplifier to anyone who listens to it since 95% of an amplifier’s playback resides in the first few watts.  However if I were marketing to engineers who already know it all, I would call it class AB1 and spare them the boredom
of an explanation.

Nevertheless to squelch this newly adopted rumor that a ZMA is 33 watts, I have taken the time to make a video of how we measure the power output.  It will be a helpful video for ZMA owner’s so it was no problem to make.

Steve, thanks for weighing in and clearing up the confusion -- that I started!  :P  

Can you comment on how Ultra Linear Output Stage feedback relates to "No negative feedback?"  The article referenced by Denizen mentions that feedback is used for ULOS but I'm guessing it's not the same or of a different order of magnitude?  And is the ULOS used in the ZMA the same as that of your amps with the UFO transformers or is a different concept altogether?

I realize that the proof is in the sound but somehow I'd like to be less confused when reading the add copy when comparing the various Decware amps.

Steve, thank you for taking the time to answer my questions.  Fortunately, I've just taken your "ad copy" at it's word and I run a ZMC1, ZP3, CSP3, ZMA into HR1s and couldn't be happier!

One other minor thing I've wondered about, since you don't specifically say, is if the ZMA preserves the even ordered harmonics like your SET, Torii and Torii Jr amps?

I find that I listen more in the range of "meters just starting to move" more and more.  So, I might be pushing the Class A into AB.  I can't help myself -- it's just so darned good!  

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Yes, if you watch the video, I show you the harmonics of the ZMA in real time and they are dominated by even orders.

Steve