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09-25-2007

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	21
Post ID:	5413
Reply to:	5412

All my Berning amps

Merlin wrote:
Are your observations regarding the ZH270 relating to comparisons with other push pull designs or SET's?

Well, both push-pull and SET and also some transistor designs as well, as I used to be quite a fan of Nelson Pass and have an old Threshold and Aleph amp lying about.

Merlin wrote:
I wasn't aware you had owned two Bernings - just the one. Which models did you own? The ZH270?

Well, the one was the ZH270, whose name I couldn't remember (all those numbers and letters!). Also, there was the EA-2101, a wholly different design but made by Berning. Also there was the BaM-235, Berning's car amplifier. So actually three if you count that one, but I think the ZH270 is the most salient one for this discussion as it shares the toplogy.

Merlin wrote:
Secondly could you explain which characteristics of the recording are destroyed, and what mechanism David Berning uses to acheive this?

Musical loss is never intentional. We try to expunge the bad (distortion, noise) and preserve the good (music). But, as with any real-world process, this happens imperfectly. When we polish silverware, the hallmark is rubbed away a bit; when we scour a dirty pan, the surface is scratched, when we shave, we may get a cut.

I simply mean that Berning's topological design, while innovative, is a solution with some clear benefits (e.g., reduction in hysteresis) but there will be some losses as well. To my ear, while I clearly heard the benefits, there was a loss of musical involvement which I value highly. How does it happen, specifically in the ZH270? I don't know; if I did I would fix it. I expound on this conept in more detail in the thread:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?postID=4116#4116

09-25-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	22
Post ID:	5414
Reply to:	5412

Siegfried - the monsters killing hero.

Merlin, I have nothing against Bernings, in fact I found it all educational as I never had exposure to them. Well, perhaps I did hear them at some kind of hi-fi show but just did not paid attention. I hardly believe that I will hear Bernings as I’m loosing more and more interest to amplifiers out there, do not go to shows/demos and hardly ever willing to practice lately in listening of other playbacks. The glories and Moronic times of audiophic Psychoticism are gone for me... I have interest only in a very limited scope of subjects that I am interested, no more or less, and my experience with “new” is restricted not my exposure but my wish…. That all makes highly unlikely that I will hear that Siegfried SET.

Considering above, I might only to bark to the passing train, regardless if the train cares gold of shit. So, subsequent with “barking instinct” I will tell you what I do not like in that Bernings saga – I do not like how David Berning and you talk and to think about the advantages of Berning topology.

I read careful what David says about his ideas and there are very many slippery moments that do not make me comfortable. I would defiantly not implicate David in the moments but in what we hear from others we’re mostly looking in their expressed thinking the moments that are related to our experience. In what David say I like many aspects beside the rational the leaded him to invention of his amplifiers. In his experiments David got rid of transformer and replaced it with a DC transformer, claiming that it is “better”. His “A Time to Dream” section is clearly indicates that David tend to conceptual thinking and in design his amplifier he was fighting with absentminded engineering objectives and design an amplifiers instead of designing of Sound, Do you remember the biblical tail how Jacob left his uncle Laban , the spotted sheep story? I personally accept or believe in nothing less than that “designs philosophy”. Therefore the David’s complains about what he see dissatisfying in transformers, cyclotrons or Futtermans I take with a certain dose of skepticism.

If (a definitive “if”) that Siegfried sounds interesting then it sounds interesting but it is NOT because what you and David are trying to convince yourself and others. The allegatively-positive sound from Siegfried is NOT an indication that transformers are bad and I feel Davis preoccupation with the subject of “transformer hate” is juts his obsession. (That he is perfectly entitled to have, BTW).

As for me, I feel a little difficult to accept an idea of using 70-years ago-made direct heated triode and then drive with it a pulse amplifier. From a different perspective I did not feel absurd a couple years ago to accept an idea of a time delay machine for upperbass horns that use FM modulator/demodulator, what a hypostat!!!

The “resulting sound” is the only one thing that maters, right? If so then, let toss away the prejudges and let the that Siegfried to fight for it’s space under sun. It looks like he does the things for you and for your ported JBL driver, the driver that enfeebled you to feel “extremes limitation due to the ML2’s core saturation”....

Ok,ok, ok it was not your quote but it was very close… :-)

Rgs, Romy the caT

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-25-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	23
Post ID:	5415
Reply to:	5412

Do not hate me, the transformer.

Merlin wrote:
Secondly could you explain which characteristics of the recording are destroyed, and what mechanism David Berning uses to acheive this?

Actually it would be a reversed question to David Berning:

“What kind evaluation mechanism he used in order to assert that his pulses -modulating impedance matching devise is more characteristically–transparent then a transformer.”

What is particular should be under the aim BTW is not the “characteristics of the recording” but the “characteristics of performance”. There are many audio devises with transformer in a signal path the do sound very correct. World it mean that the transformers are not the evil and were not the quality party to begin with?

The caT

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-25-2007

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Merlin
Cheam, United Kingdom
Posts 50
Joined on 03-03-2007

Post #:	24
Post ID:	5416
Reply to:	5414

Different strokes

I think it is a simple case of different strokes for different folks.

Drdna writes about communicating the essence of sound - I write about the essence of music. He writes about wondering what Coltrane was thinking. I write about hearing him looking across at Jimmy and Elvin, smiling, and taking off together as one. Of improvised unity and rythmnic togetherness.

What the Berning provides that I find utterly lacking in so many popular SET's is that rythmnic control, that feeling of all the musicians playing as one and with great joy. That's where the essence of the music lies to me - the essence of sound may lie in the precise timbre of Trane's tenor but in it's own it is just that - sound. Not music.

I'm pretty convinced that most SET's suffer rythmnically and I ddo not know exactly why. The OPT and PS regulation are the most likely suspects, the former measurably causing non linearities at the bottom end that is audible in most designs. The only SET I personally have heard that seems to over come these limitations to a great degree are the Border Patrol S20 and the Siegfried, although I would say the latter isever so slighly sluggish in comparison with it's PP brother. The PP design excites whilst the SET moves. Again a case of horses for courses.

For my tastes the two amps I mention get closer to providing everything I want than any others. I cannot live with timing failures. I find a jazz quartet utterly boring if they sound disconnected from each other - regardless of how wonderfully tangible their instruments sound. That's high end hifi not music.

In my experience, very few output transformers are transparent enough to not heavily impact on the signal passing through them. Some of the finer Japanese iron can sound delightful, but in most designs the non linearities at the frequency extremes ruin the illusion of reality all too easily depending on program material. As an aside, one listen to a tube vs SS Mcintosh dem will amply highlight the infludence the OPT has on the sound you hear. I personally thing David Berning's goal is a very important one - and one that has very clear benefits that are essential to me. Romy, you too are essentially trying to remove the non linearities of the OPT from the replay system in your own way but using iron dedicated to narrow bandwidths. David's solution seeks to achieve similar benefits on a more practical level. The 811 based Siegfried sold for $6K. The quality on offer at that price rather puts much of today's overpriced audio jewellry into perspective in my opinion.

Anyway, in closing we are clearly looking for different definitions of ultimate musical enjoyment and veracity. To me, the Bernings I have used have made many other amplifiers sound so utterly electronic as to almost seem broken. That would include Nelson Pass' designs - although I do rate his active crossover very highly. The fact that you will never find a Siegfried for sale speaks volumes. Proud owners are quite likely to take them to their graves! The new Western Electric design will be interesting.

09-25-2007

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	25
Post ID:	5417
Reply to:	5414

The specific problems with Berning's design

Romy the Cat wrote:
David got rid of transformer and replaced it with a DC transformer, claiming that it is “better”.

And I should point out that not only is there still a transformer in the circuit, but many other components are added, including transistors. I have no doubt that this topology give reduced measured hysteresis distortion, but I wonder what all the other components are doing to the sound?

It really depends on what you focus on in sound. If you value inner detail, speed, and clarity above all else, I bet you would love these amps. I remember Berning amps as being very accurate in a unassuming way. Still for me there is more to music than inner detail, which is why I don't own the Berning amps any more.

09-25-2007

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

Post #:	26
Post ID:	5418
Reply to:	5412

Early in the thread

Merlin, early in the thread you seemed to be enjoying your position as the only person who knew what the hell you were talking about, and not much has changed since. Are you trying to share what you know or hold fast to some pre-conceived ideas that you keep pulling out like hole cards?

Please understand that I am not trying to say that I know more than you do about your amp, or your speakers, or whatever. I have heard the amp on two occasions, with three pairs of speakers, enough I think to make the few specific comments about the sound I heard and, more importantly, enough to make the decision that it's not for me, sonically, compared to what I did choose. I did say why. Conversely, I bought Lamm ML2s although I heard them but briefly on two occasions driving speakers I do not even like. Clearly I guessed at Siegfried's circuit details, but there is the circuit in question, above, no thanks to you, and obviously I was not far off the mark, not that I am worried if I was. Meanwhile, if your aim has been to shine light on the Siegfried - you being the expert - your reproach seems all out of proportion to what you have contributed so far.

But perhaps we are talking about two different things here? I hoped to find out what specifically you do not like about DSET and how/whether the Siegfried (once you revealed it) solves those problems in terms of sound. I also hoped the discussion would broaden into OTL versus OPT designs, in practical terms, as they relate to problems we all deal with in our hobby, again with the emphesis on sound.

I don't give a rip about the theoretical advantages of having perfect tube transfer characteristics if I don't care for the results in my listening room, not to mention the fact that two different signal tubes of the same type in the same amp give you two different sounds, anyway. At the same time, I am always casting about looking for good ideas to pirate, modify, etc., to make use of them in a way that works for me.

I concur that the Siegfried is worth a careful listen by SoundClubbers, given that it is not over driven, and I will not say that about every amp. But that was not where or how you came into this. Also, I would not go so far as to say that the Siegfried is a do-all, FR amp, as you have obviously determined for yourself, remembering that your initial post on the subject was a sort of underhanded slap at Romy's claim that DSET is better than expensive SETs, which claim you have hardly addressed, really, let alone countered.

I am still not clear if you are saying that the Siegfried represents a least-and-therefore-best approach or whether you are repeating design desiderata to bolster claims that this is The Amp. How HR got into it, I have no idea.

Best regards,
Paul S

09-25-2007

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Merlin
Cheam, United Kingdom
Posts 50
Joined on 03-03-2007

Post #:	27
Post ID:	5419
Reply to:	5417

Circuit.

drdna wrote:
Romy the Cat wrote:
David got rid of transformer and replaced it with a DC transformer, claiming that it is “better”.
And I should point out that not only is there still a transformer in the circuit, but many other components are added, including transistors.  I have no doubt that this topology give reduced measured hysteresis distortion, but I wonder what all the other components are doing to the sound?

Here's what Berning said about the circuit when questioned

"The ZOTL falls into a generic class of amplifier described by the acronym OTL both technically and in spirit. The power conversion transformers called out by the patent cannot and do not operate at audio frequencies. The semiconductor devices called out by the patent drive these transformers at a fixed 250 kHz and do not operate at audio frequencies or as amplifiers. The patented ZOTL circuit is a two-way coupling circuit that performs impedance matching like an audio output transformer, but does not have any of the limitations and distortions imposed by audio output transformers. This circuit is in no way a buffer, such as a transistor output stage in a hybrid tube-transistor amplifier. There is no power gain, and more importantly, the speaker “sees” the tube transfer characteristics and the tubes “see” the speaker’s dynamic characteristics."

Next something I have said in the past about the circuit when it was suggested it was a switching amp

"Power is transferred from the valve to the speakers as the plate current in the valve varies in response to the audio signal on it's grid. As the anode current increases, the current drawn from the converter bridge power supply increases in proportion to the converter transformer ratio. Since the speaker is connected in series to the primary winding , it's current increases by the same amount.

The switching transistors in the impedance converter bridge are not variables in the signal path. The current through the loudspeaker load follows the transfer characteristics of the valve. With a Mosfet switching amplifier, the signal is converted to PWM . With the Berning this is not the case . So again from my point of view, to use the term switching amp is misleading - switching amps are Class D. This is not class D"

And to help matters further , something the late Terry Cain had to say on the subject

"The Bernings use a device, (not mosfets or transistor nor another gain stage)to change impedance up into mhz, and to an output suitable for driving spkrs. The -device- is a unique Berning designed inductor of sorts, has a "wound" turns ratio, this is where the confusion lies. The tube directly drives the load, through this high freq "inductor".

Inductor is a misnomer because no "inductor" has ever been made this way.

Personally I think it is every bit -otl- as circlotron only much more advanced. OK, it uses less than 1% of _some_ inductance so it is still using inductance but in a weird and unusual way. So in a way it -has- an inductor. But not at all suspect to the usual saturation and inductance distortions like every other tube amp, except circlotron and hybrid otl's.

Berning is unique, and far away the most advanced circuit for tubes period. True to thermionic dissapation as a musical fuel for amplification, it does things no other amp can. It's very stable, efficient and very low in distorion and hum. DC couled and flat response to 2hz and ultimate stability."

And finally the flowery prose of Doctor Gizmo,

" MARK MY WORDS: I have seen the future and it is ultra high frequency switching power supplies with regulators for tube amplifier who aspire to the thermionic concresence of coolosity. David started this trend almost two decades ago and now others will soon follow. Remember my 100% batting average.

Because so few have experienced David’s new ZOTL, and even fewer the single-ended version, it is easy to understand the angst in the Rec. Audio chat groups. There is much whining and complaining about this circuit because it is so threatening to makers of conventional transformer coupled amplifiers and conventional OTL amplifiers, but let me assure you that like The Harmonic Plasma Transducer, David single-ended 300B ZOTL is, in the truest sense a breakthrough in the most serious end of the audio arts. This circuit is not an incremental step, but a major leap forward in thermionics, is totally unexpected, understood by few, including me, is totally "untweakable", and the best reason in the world why others would want to assassinate David. Who would have imagined listening to a directly heated triode without an audio transformer? Who would have imagined a single-ended directly heated output transformerless amplifier....and the elimination of OTL’s impedance sensitivity?

Let me be clear that neither of these products are designed for "sodbuster" audiophiles. This is ultra serious stuff for those who have been witness to the thermionic fire; to whose who have walked across the burning coals, and are living on the edge. This is the place you arrive at after you have taken Sid Arthur’s journey, and know the sound of one 300B clapping. If you have any doubt about David’s alien genius just consider this...in a ten pound box David is able to create what it took the savants of New York Audio Labs to accomplish in a 250 pound form of the Futterman OTL-1. After listening to ZOTL when you pick up the box, which weighs less than you preamp, your brain goes.....Duh! How is this extreme level of anti-gravity performance possible my fellow earthlings?"

I post these to shed some background and to answer some technical questions - not to make any claims as Paul seems to think. In a subjective hobby there is no one true path.

Paul, you have an attitude - please let it rest. To correct some errors in your rather agressive post though, no I did not make any claims other than stating that my SET was not bandwidth limited as Romy had suggested all SET's were. And secondly, no you didn't guess I was talking about the Berning - Be did. Given your ignorance of the subject at the beginning of the thread I now find it most amusing that you claim to have heard the device on numerous occasions and preferred the Lamm. Forgive my cynicism - you appear to feel threatened by the unknown here. There's no need to be - none of us know everything.

09-25-2007

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

Post #:	28
Post ID:	5420
Reply to:	5419

Everything and more

Thanks for the extra information, Merlin, it tells much. Please re-read the post you took umbrage with and you will see that I said I took a guess about the circuit (once you confirmed the amp's identiy), and I did not say that I guessed the make and model of the amp [from your teasers]. And I don't get this: Did you expect me able to identify your amp from your teasers and also display solid technical understanding of the amp for you, given that my experience with it is hearing it twice? Or are you saying that if I understood it better technically I would have heard it differently? I don't understand.

FWIW, I really don't care specifically about OPT or OTL, size, weight, color, theory, etc. PER SE, with respect to hi-fi gear, and therefore I have no reason to resist new ideas, per se. I may be lazy and cynical in my own right, but truly, I am not "invested". I only keep track of tech information to further my own personal ends, and I air my thoughts just to share ideas and get some feedback and perhaps some fellowship.

In fact, if I heard the Siegfried again and thought differently I could just up and get one with no inner sense that I was violating any personal creedo. You could say, I told you so, and I would say, sure did.

I am comfortable with your stated preference for the Siegfried over the ML2, and it is easy for me, especially now, to accept as a given that you have heard both and then chosen as you did. I wish you had been as forthcoming earlier; but this has been a fun thread, after all.

Bet good money that I will walk a mile to hear the Siegfreid again if the chance presents itself.

Best regards,
Paul S

09-26-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	29
Post ID:	5423
Reply to:	5419

The transformer-less Masonic secretive handshake...

Meriln, this is one of the subjects that disturbs me in your description: your bring OTL consciousness to justify Berning and you bring all those foolish OTL people as witnesses to give credentials to Berning. We all know Doctor Gizmo and all know his view about the things and the reasons of his interest in the things. Read my article “Immediate Gratification by Surrogate Sonic Effects” at:

http://www.goodsoundclub.com/GetPost.aspx?PostID=3611

Dr. Gizmo was not a fool but he knew that he writes for fools. So, his cherishing and blabbering the entertainable and hyper-selebrateable mediocrity was his routine, and it was not something that other might care or take under consideration. The late Terry Cain was in the same, or even in the more shattered boat. He was very pleasant guy personally but his results in Audio were beyond any rational criticism. Presumably his understanding of Sound and Audio methods were at the same level and It is no surprise that all “those” people crowded around the OTL world. I do not mean just the Gizmo and Terry but all that community of full-range drivers with sewer-pipe-horns, driven by some kind of Atmosphere OTL. I am not accidentally mention the Atmosphere amps – people involved with them should have ears cut, Still I do know a lot of people who do sing serenades to the Atmosphere OTL… The familiar serenades…. I would not even mention your comments about the “facts” that no one sell the Berning amps – it was openly cheap and you know it.

What was actually interesting in this thread were not your attempt to convince yourself publicly that Bernings is worthy amp but you posting your own thoughts about your amplification. I think if you did it initially I would eliminate many unnecessary posts. Still, as I can see it, - making amplifier that would make jazz to sound Gizmo impressive is as simple/primitive as to compete with the handicap athletes from local Special Olympic team.

I still do not feel comfortable with Berning idea and I relay do not see rational behind what David offers. He butters up people with fear of core saturation at LF but it is truely bogusness. There are zillion way to deal with the problem, block DC with a cap and use no gap-transformer for instance. I do not say that it is better solution for the “transformers fear” but it will sound like shit and at the same time have no “feared saturation”, think about it.

What I do say is that each conversion mechanism has own language and own intrusion into the fine, and in many instances mysterious, mechanism of sound organization. I do feel (and that feeling is NOT backed up by any evidences) that pulses modulator might be more intrusive and more disturbing “ceremony” then a transformer. A transformer has easy understandable, easy predictable and easy measurable boundaries - LF limitations. There are ways to deal with it (DSET one of them, BTW). Also, transformers (or DSETness) allow mitigating of demands. You might go for ambitious transformer or for DEST if your sonic objective, your room and the capacity of your acoustic system might accommodate those demands. Dose it mean that if you use no lower then 60hz capable speakers (most of the speakers out there) then you do not need Berning’s impedance matching as it would not stress low end? Sure, David Burning offers a very different approach but it has nothing to do with the fact of transformer absents, in fact I would not call David’s amplifiers as SET at all as they’re not truly triode amplifiers anymore.

I certainly am not saying that the Berning conversion is bad but I do say the David’s conversion is much more complicated in terms of sound transformations. David is preoccupied with pushing his Zero-Hysteresis hyperbola and it is very much possible that his design do have no hysteresis. So what? David, stresses juts one among dozens others measurable factors, and it is among those factors that we know. Do I have to remind you how many amplifiers sound out there where their designers have in this mind ONLY the lowest number of harmonic distortions?

You see, we do not hear distortions. Let me say it again, as it is very loaded statement: humans do not hear distortions. We do not register distortion but only hear ONLY the residue of mechanisms that create the distortions. I afraid that Mr. Berning’s ZOTL ideas have larger opportunities for exhibiting various electronic contamination of sound becose his conversion is MUCH more complex. Will those contaminations be shown on David’s Berning measurement tools? Ro answer this question it is necessary to look much further then “design concepts” and to use different assessing methodologies that would be serving the interests of Sound instead of the interests of design objectives….

BTW, the comments of some folks who reportedly heard Bernings amp as who found that it was juts a “good” Hi-Fi is a good illustration that to build an amp having only no-hysteresis objective is too undemanding objective to have.

I have a local guy here in Massachusetts: Dan Banquer. He is some kind amplifier designer that trying to make noise in the same level community where Bernings makes waves. Dan has a mental fixation that amplifier should not hase noise and all his metals capacity completely enslaved with this objective. I heard his amps in his home a few years back, and it is true – his amps have no noise; however it is all that his amps do as in any other aspects of music reproductions his amps demonstrate the intelligence of a refrigerator. When Dan Banquer played to me his amps and asked me what I think I told him, after which he kicked me out of his house – he juts did not know that he was doing a favor for me by aborting that session…

What I am trying to say? I am trying to deliver a thought that in a seriously sounding amplification there is a LOT OF MORE then absent of hysteresis-inspire distortions and hate of transformers. Your pointing to Berning amps was very good thing but I hardly see it as some kind of Pandora Box. Rather I see it as another entry in a long line of “opportunities”, the opportunities that might or might not burst though then a higher level then a Masonic secretive handshake …

Rgs, The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-26-2007

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Merlin
Cheam, United Kingdom
Posts 50
Joined on 03-03-2007

Post #:	30
Post ID:	5424
Reply to:	5423

OK

If there's one thing I hate about internet forums it's people postulating about sounic characteristics and possible failing in equipment they have never heard.

FWIW Romy, David has been making waves and creating groundbreaking designs for over 30 years - this is no new kid on the block. David is preoccupied with improving on existing solutions. That is his raison d'etre. I think he succeeds in many areas and a number of very knowlegable individuals tend to agree with that. If you don't, that's fine. Opinions are interesting. But good opinions are based on experience.

As I've said - I think we listen for different things. I can't live with the failings of Lamm for instance, nor can I abide any number of single ended triodes. The Siegfried addresses my concerns neatly and successfully - and is without doubt as pure a form of triode amplification as anything on the market as evidenced by the transfer characteristics being preserved so clearly.

I'm not here to "big up" the amp anyway - you can't buy one even if you want to. But at least now you are aware of the existance of amps that don't suffer from the traditional SET failings.

09-26-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	31
Post ID:	5425
Reply to:	5424

“….the linearity of the Berning in comparison with the Lamm is quite remarkable”

Merlin wrote:
If there's one thing I hate about internet forums it's people postulating about sounic characteristics and possible failing in equipment they have never heard.

Merlin, I was under impression that it is very obvious that whatever I am able to say on the subject is pure speculation. You know very well that if I did have any personal familiarity with Siegfried amplifier then I would speak with very different tone and manner, regardless if I were right or wrong. I did not see me postulating about “sonic characteristics of Siegfried” but rather I explored my initial reaction to the Siegfried’s anecdotic rumor. I do not see anything wrong with it …

Merlin wrote:
FWIW Romy, David has been making waves and creating groundbreaking designs for over 30 years - this is no new kid on the block. David is preoccupied with improving on existing solutions. That is his raison d'etre. I think he succeeds in many areas and a number of very knowlegable individuals tend to agree with that. If you don't, that's fine. Opinions are interesting. But good opinions are based on experience.

But I do not think you would be satisfied if in responds to your motioning Siegfried I would reply only with word “OK”, would you? You went a long way from obscure phraseology of your initial posts to quite eloquent explanations of own views – I appreciate it and I think it serves good service to the subject of this thread.

Merlin wrote:
The Siegfried addresses my concerns neatly and successfully - and is without doubt as pure a form of triode amplification as anything on the market as evidenced by the transfer characteristics being preserved so clearly.

The “transfer characteristics being preserved so clearly”… Interesting view….

Merlin wrote:
I'm not here to "big up" the amp anyway - you can't buy one even if you want to. But at least now you are aware of the existance of amps that don't suffer from the traditional SET failings.

Merlin, I think you are missing a whole point. The Siegfried might not suffer from the traditional SET failings but it is not a SET topology anymore. It is still a single-ended amplifier it is uses triode of course but it sound does not necessary is indicative to the sound, advantage and disadvantages of single-ended amplifiers. If you have an out stage of CD player build around a bipolar transistor and the CD player us used in a broadcast of in your local FM radio station then would it be possible to label the sound that you pick at your FM tuner as something the is characteristic to the bipolar out stages? I doubt. Siegfried own class amplifiers, I think and I wish your guys when try to talk about advantages of Siegfried will talks about it’s own sound instead of accusing SET in what they do. A reasonable question would be: why I do not feel that you just do the following:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=432

because so far I did not hear from you that you explore the subject of SET appropriately. David, decagrams do not show SET operation but show actually an operation of a broken amplifier. You suggest that your 93dB ported driver, which is notoriously “upper bass” (like all the rest JBL bass drivers), did not allow you to be happy with ML2 extreme frequency. You might be right in your conclusions (even if you are Jazz listener) but I doubt that you are correct claiming SET for your finding. Then we have Terry Cain, the most indicative person in this testimony. Do you know if Terry used Siegfried during his demonstrations? Because it he did then I might heard the Bernings and the only question I would have: “how the Berning’s frequency extremes helped to Terry Cain’s Sound”? Do you see where I am coming from? I am trying to put together what I heard from numerous Terry’s attempts and your comment: “large increases on 2nd harmonic at the bottom end”.

Rgs, The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-27-2007

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Gregm
Greece
Posts 91
Joined on 02-16-2005

Post #:	32
Post ID:	5431
Reply to:	5424

OK, a word on approach & point of view

Merlin wrote:
If there's one thing I hate about internet forums it's people postulating about sounic characteristics and possible failing in equipment they have never heard.

Quite so. However, the approach here is simply to ask -- it doesn't matter if I've heard the thing: you have, and can talk about it.

David has been making waves and creating groundbreaking designs for over 30 years - this is no new kid on the block. David is preoccupied with improving on existing solutions. (...) I think he succeeds in many areas and a number of very knowlegable individuals tend to agree with that. If you don't, that's fine. Opinions are interesting. But good opinions are based on experience.

OK, that's where you come in: you have the experience, so it's fine. We don't need the references to knowledgeable individuals. Your well supported opinion will suffice. You talk first-hand...

But at least now you are aware of the existance of amps that don't suffer from the traditional SET failings.

Quite. Hence the interest in obtaining details about said amp, the set failings as you conceive them, and the specific application that makes you happy.

Not to discourage you, but here it's not a matter of challenging your positive experience -- rather, it's a matter of understanding how you came to reach that positive opinion, and the underlying application from which you sourced this satisfaction...
Educational, if you will, exchanging views. Really.

10-02-2007

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morricab
Posts 51
Joined on 07-13-2005

Post #:	33
Post ID:	5489
Reply to:	5398

Underdamped bass on SETs

"Indeed for classical work I often find a slightly under damped bass response to be emotionally evocative and of benefit to the illusion of the acoustic"

Have you looked at the primary cause of this issue with most SET amps? I can tell you that the number one reason for it is output transformer saturation. Another is an inadequate driver stage. Get these two things right and you will not have sloppy underdamped bass. Take the KR audio amplifiers as a good example. Their latest generation hybrid amps (yes the input and driver stages are SS) show almost no distortion increases at bass frequencies. Other SETs regularly show >1% in the bass even at almost no power! OTLs have the problem of dynamic bias drift when asked to deliver a lot of current (ie. in the bass). You can see this quite clearly when you watch a DC offset meter as it pulls to one side or another with big bass signals. This always means a big increase in distortion and therefore sloppy bass. IF you get the output transformer right you will have transparency and good control in the bass frequencies and a high damping factor, requiring a lot of signal destroying negative feedback, is not necessary. Prevention of transformer saturation is sadly neglected by most SET manufaturers and perpetuates the myth that these amps can't have good bass control.

10-02-2007

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morricab
Posts 51
Joined on 07-13-2005

Post #:	34
Post ID:	5490
Reply to:	5424

The Lamm and OPT core saturation

Merlin here is the Stereophile measurements on the Lamm ML2.1
http://stereophile.com/tubepoweramps/1004lamm/index4.html

As you can see the rise in distortion vs. frequency shows only a small rise in distortion even down to 10Hz. This is an indication that the transformer that Lamm selected is adequate for its job without saturation. To get a comparison of this look at this SET.

http://stereophile.com/tubepoweramps/304antique/index4.html

As you can see in Figures 9 and 10 the distortion in the bass is gross and will for sure lead to an opaque muddy mess in the bass. The Lamm is very similar to a SS amp in this regard.

Now look at a PP tube amp.

http://stereophile.com/tubepoweramps/807ar/index4.html

As you can see there is a marked increase in the bass distortion here as well, although it is still below 1% at the given power rating. This is a new PP tube amp design and has a marginally adequate OPT.

Here is another SET from Air Tight that has a good reputation but again somewhat flabby bass:
http://stereophile.com/tubepoweramps/687/index6.html

It is complicated to see but at 16 and 8 ohms the bass distortion rises dramatically at low freqs.

Now here is something quite different, a hybrid amp that measures like a good SET amp:
http://www.soundstagemagazine.com/measurements/monarchy_se160/

Finally a Lamm PP amp the ML1.1:
http://www.soundstagemagazine.com/measurements/lamm_ml11/
Note also that it has almost no distortion rise in the bass and it has very good bass control and definition.

Here is a KR Audio amp model VA340. It is a hybrid SET (tube output!!)
http://www.vi-fi.nl/assets/s2dmain.html?http://www.vi-fi.nl/xtrartikelen/testen/meetrapportkraudiova340/index.html

Note again only a slight rise in low freq distortion. This amp has bass control as good or better than top SS amps (more musical but very controlled). Note that the damping factor varies between about 5 and 7 and there is no neg feedback in this amp.

10-02-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	35
Post ID:	5491
Reply to:	5490

Advantage of disadvantage of a given topology

The excellent post, morricab! There is secondary point in your post - the core saturation is not the fundamental problem of SETs but it is become an issue when we go for power. If you do not need to drive 92dB sensitive bass drivers with a 6W SET and the core saturation might not become the subject.

What is important in this thread is that Devid Berning promotes his topology as something that offsets the imperfection of the transformers and particularly the core saturation problems. However, as we clearly see the core saturations are a problem only if the designer is Morons. Yes the truly HF capable transformer for high current as with high inductance to keep the saturations of the back is very difficult and costly to make and here is where the DSET topology save everything and has virtually no limitations. So, I frankly speaking do not take Devid Berning’s pitching about the harm of transforms seriously, in fact I feel he fools himself in it. The Berning’s solution is a perfectly reasonable stand-alone solution – it is good or bad solution - it still does not illustrate anything about the subject of SETs and output transformers.

So, what is better: Berning’s DC transformers circuits or the classic gaped AC transformers? Who knows! It would be interesting to put together a properly made SET against the Berning amps use the same diver and the same output tubes. Still, it would likely portray the specific implementation then the advantage of disadvantage of a given topology…. Listening the stand along Berning would do as well….

If to place bids then I would bid on the classic SETs as I feel that it would have way less convoluted and less intricate conversios. Still, my bid worth as much my Daw predation for a new day…

Rgs, Romy the Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

10-02-2007

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morricab
Posts 51
Joined on 07-13-2005

Post #:	36
Post ID:	5492
Reply to:	5491

Saturation contd.

What I find interesting though, Romy, is that many of the SET measurements show gross distortion even when putting out very low power, which suggests that they are saturated from the high static DC current running through them as they must for a Class A SET. You are also right that to get everything you want from an output transformer requires a VERY expensive construction and top materials. However; even an expensive transformer is no guarantee of success. Look at the stereophile website (see you thought there was nothing useful there but in this case the measurements tell a lot!) at the WAVAC amp. This crazy priced SET has very bad distortion in the bass. I am sure the OPT is very expensive in this amp but the manufacturer apparently never bothered to check if the OPT they chose was appropriate to the situation! Of course it will sound big and wooly and bloated with 10% or more distortion.

http://stereophile.com/tubepoweramps/704wavac/index5.html

Overall SET amps like Lamm and KR audio sound cleaner and more correct AND they also measure cleaner and more correct...with little or no corrective feedback (Lamm uses a bit I believe and KR audio uses none). I think that in fact measurements DO mean something when the amp is not using negative feedback, which seems to mask the true behavior of the amplifier (ie. open loop linearity). The more linear an amp is open loop (ie. without negative feedback) I think overall the better it will sound. This includes errors from the power supply, circuit layout (eg. hum and noise), OPT, thermal issues etc. All of these things will have a profound affect on the open loop linearity and many designers cover up these issues (but do not cure them) with negative feedback.

I mentioned the dynamic bias issue with PP amps. It is more a problem with OTL but it is also a problem with transformer coupled PP amps and is partially why they don't achieve the overall purity of a SET. When you bias an amp statically, you can match them pretty closely. However; put a demand on the tubes and watch them diverge! I know of only one amp on the market that addresses this issue with a kind of dynamic biasing scheme (not disclosed) and that comes from VacuumState. It is an 18 watt 300B PP amp (the designer refers to it as differential as it has no phase splitter and is fully differential) that is the first I have heard to get the low level resolution and tone color of a SET. Also bass is quite controlled and natural. It is better than most SETs I have heard and as it uses a very good OPT, my guess is that it has minimal distortion in the bass as well in addition to being zero negative feedback. www.vacuumstate.com

10-02-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	37
Post ID:	5496
Reply to:	5492

What might be more simplistic and elegant?

morricab wrote:
You are also right that to get everything you want from an output transformer requires a VERY expensive construction and top materials. However; even an expensive transformer is no guarantee of success.

Sorry to accent it again but the DSET is. A LF transformer of DSET dos not care about capacitance and HF phase shifts - is just pumps inductance with core mass or with turns. The MF-HF transformer of DSET do not care about inductance of power saturation as LF are filtered out from the channel. What might be more simplistic and elegant?

morricab wrote:
Overall SET amps like Lamm and KR audio sound cleaner and more correct AND they also measure cleaner and more correct...with little or no corrective feedback (Lamm uses a bit I believe and KR audio uses none).

It would be interesting to learn why Lamm wean for feedback in ML2. Obviously he wanted to keep the amp as much as possible accommodated for wider margin of perspective speakers. Also he had no good driver in input stage as 12AX7 can not handle the line-level input (too low bias). So, he jacked up the 12AX7’s bias with feedback in order do not drive the input stage into overload.

morricab wrote:
I think that in fact measurements DO mean something when the amp is not using negative feedback, which seems to mask the true behavior of the amplifier (ie. open loop linearity). The more linear an amp is open loop (ie. without negative feedback) I think overall the better it will sound. This includes errors from the power supply, circuit layout (eg. hum and noise), OPT, thermal issues etc. All of these things will have a profound affect on the open loop linearity and many designers cover up these issues (but do not cure them) with negative feedback.

I mentioned the dynamic bias issue with PP amps. It is more a problem with OTL but it is also a problem with transformer coupled PP amps and is partially why they don't achieve the overall purity of a SET. When you bias an amp statically, you can match them pretty closely. However; put a demand on the tubes and watch them diverge! I know of only one amp on the market that addresses this issue with a kind of dynamic biasing scheme (not disclosed) and that comes from VacuumState. It is an 18 watt 300B PP amp (the designer refers to it as differential as it has no phase splitter and is fully differential) that is the first I have heard to get the low level resolution and tone color of a SET. Also bass is quite controlled and natural. It is better than most SETs I have heard and as it uses a very good OPT, my guess is that it has minimal distortion in the bass as well in addition to being zero negative feedback. www.vacuumstate.com

What you say sounds logical to me but I have no further PERSONAL experiences with feedback in power amps. I heard many of then with different feedbacks, including positive feedback but was about all that I did with feedbacks….

Rgs, the caT

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

10-02-2007

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

Post #:	38
Post ID:	5499
Reply to:	5496

IMO the Berning sounds like nice PP with some well done feedback

And I do not mean this as a criticism.

I had for some time an "original" Music Reference RM9, which was made by another well-educated genius, Roger Modjeski. The RM9 was AB PP with adjustable bias and feedback/gain, with 6DJ8 drivers and a choice of EL34, KT88 or 6550 output tubes.

The idea was to set feedback/gain by ear according to the speakers used, but I found that the low-feedback/ Hi gain setting was the only way to get proper timbre, harmonics and bass, regardless of the speakers I used. Yes, bass with more feedback had more "impact", but it was not musical.

I have no idea whether/how the Berning Siegfried uses some "deniable" form/variant/iteration of "feedback" to co-modulate some part of the circuit, but it did sound to me that something in that circuit is sensing and reacting to signal modulations in a way that audibly suggests some kind of feedback to me. Perhaps this is just an artifact of the complex switching PS, I absolutely don't know. Please understand that to me this is not a "problem" on the face of it, since I really don't care about anything but sound in my listening room and decent reliability. I absolutely hear the feedback working in the ML2, and I happen to like the effect a lot. However, the Berning simply does not "breathe" as well as typical decent SETs do, at least when they are in their comfort zones, and it does not offer enough else to make up for this, IMO. Push the amps, however, and the tables turn. The Siegfried may offer "less" going in, but it maintains its character/delivers its best better/more consitently under stress. At least, this is how I remember it. But in any case is this the "transformerlessness" at work or is it some other genius application?

I have not had enough experience with the ML2s to speak of the audible effects of transformer core saturation in the design. In my case this owes to the fact that the amps just stay stable and sound good if they are biased correctly, so the issue has not come up. I would like to have someone listen to my system and point out the core saturation. So far the only thoughts I've had of it were dispelled when I found runaway bias, and correcting that problem brought everything back into focus.

I would be willing to say at this point that my problems are related to ~97 dB speaker efficiency and wayward speaker input impedance, not some problematic quality inherent in transformers. Rather, in the real world I think it is just a matter of matching the amp/transformer to the task at hand in order to get the best possible sound, versus cutting off the OPT to spite possible core saturation.

Right now, in terms of otimizing my present speakers, I would think of adding transformers in the form of LF amps before I ever got into scourging the demon transformers. By this I mean that nothing I have seen or heard to date has convinced me that an OTL variant is The Solution, in so far as one compares audible transformer core saturation problems to audible OTL problems. In fact, far from it.

YMMV, of course; enjoy yourself.

Best regards,
Paul S

10-14-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	39
Post ID:	5608
Reply to:	5385

David Berning at Rocky Mountain Audio Fest 2007

Welcome to the club:

"Debuting the new Quadrate Z, David Berning was displaying a new amplifier designed to output 200 watts per channel. The design is comprised totally of tubes and incorporates ZOTL technology. The amplifier retails for $29,900."

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

12-06-2007

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	40
Post ID:	6068
Reply to:	5385

Berning amps and “switching Oops” injection?

Merlin,

might I ask you if you can recognize anything from my post:

http://www.GoodSoundClub.com/TreeItem.aspx?PostID=6020

... in the sound of your Berning amp?

Rgs, teh caT

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

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