There is always progress.

But to answer your question:

Can a Amp be "timeless" and compete with todays amps?

The correct answer is ’no’. The single thing that has held back amplifier improvement is something called Gain Bandwidth Product (GBP). Over the years you may have noticed that feedback in amplifiers has gotten a bad rap. This is because limitations in GBP have prevented enough feedback from actually being applied. The result has been that the application of feedback has resulted in added distortion on account of the feedback itself, and increasing distortion with frequency above a certain point.

This has caused feedback to be conflated (and rightfully so) with harshness and brightness.

What happens if there is insufficient GBP is that the feedback starts to fall off at higher frequencies and so with less feedback comes greater distortion. If you graph distortion vs frequency you can see this in almost any amplifier made in the last 60 years employing feedback. Since the ear converts distortion into tonality and since the ear is keenly sensitive to the higher ordered harmonics generated by feedback itself, the result is harshness and brightness over the last 60 years.

That is why there are many zero feedback amplifier designs. Zero feedback is about the only traditional way of getting around this problem.

If you can manage about 35 dB of feedback in the amplifier design and there is sufficient GBP, the result is that the feedback can ’clean up’ its own mess, resulting in less higher ordered harmonics. Since the feedback is consistent at all frequencies, the distortion and the distortion signature (the spectra of harmonics) does not change as frequency is increased.

Its a simple fact that no tube amp is capable of this! You need a lot of gain and a lot of bandwidth; the former is simply not available in tube designs without associated phase shift, which would cause the amp to oscillate at some higher frequency.

There are now designs that satisfy these goals, designs that were not possible 20 or 30 years ago because the amplifying devices didn’t exist.

What this means is its possible to build a solid state amp that is every bit as smooth in the mids and highs as the best tube amps and leave nothing on the table in terms of detail, sound stage and the like, in such a way that vintage amps simply cannot compete (not that they sound bad, just they don’t sound as good). This is one of those things that is easy to hear and easy to measure.

IMO, I totally agree with atmosphere...well written and it just magnifies how stupid that statement "amp is an amp" is...

I agree too because he know what he is talking about ...

We cannot reduce technology progress to embellishment only for sure...

I would sincerely suggest to the OP to listen to an example of a modern high negative feedback solid state amplifier as described above and compare its sound quality to the Renaissance 70/70 and be your own judge. I’m not convinced that the "modern " high feedback would be  superior sounding. Hard to know which you will find musically preferable without an actual listening experience.

Charles

Aberyclark: is spot on. IMPE I have stayed with "Vintage" High End equipment. Re cap and re tube. In some cases will provide todays equipment with a respectable comparison .

So based on Atmasphere's response with "SS low feedback" designs being superior, does the Peachtree Audio Gan400 qualify as an amplifier that fulfills this description?

agree with @charles1dad

modern amps have technological advancements which allow them to reproduce sound and interact with speakers differently (and perhaps measureably better) than older amps, and especially tube amps where impedance match with driven loads can be highly variable... all this said, what combinations of amp and speaker, modern or aged, and what sound quality and character would be produced for the owner trying to enjoy music is still subjectively determined...

some modern super low distortion amps can produce a somewhat harmonically lean, clean-white, antiseptic kind of sound that may be not be favored by listeners used to a more saturated, rich, bloomy type of sound that some tube amps deliver... all subjective in this hobby, which is what makes it all the more fun...

People can argue about design in amp, and i am with atmasphere about the evident technical progress that have been made here like in any other field...

But dont forgot that the sound impression is not only created by the design of an amplifier but also with the speakers relation to a room...

And our preference each of us differ much because our listening history differ also...And our acoustic condition differ too...

There is no ABSOLUTE here...

The only rule is the ratio S.Q. /price for most of us....And the way we can optimize some system to reach the minimal satisfaction threshold...

Here acoustic control help a lot....More than upgrades half of the time...

I will live happy with my 1978 Sansui and will nor buy the superior Berning or any other very superior new design...

😁😊

«Why do you keep this old gramphone Groucho? Acoustic is timeless brother»-Groucho Marx audiophile 🤓

«Music too brother»-Harpo Marx

I would sincerely suggest to the OP to listen to an example of a modern high negative feedback solid state amplifier as described above and compare its sound quality to the Renaissance 70/70 and be your own judge. I’m not convinced that the "modern " high feedback would be  superior sounding.

Emphasis added

I completely agree with this advice, although not his conclusion :)

IME the distortion spectra (the distortion signature) has to be right; too many designers ignore this simple fact.

Most speakers today are designed assuming that the amplifier is able to behave as a voltage source (meaning it can make the same voltage output regardless of load). Some speakers in high end audio are not designed for this behavior- and for those few, sometimes an amp with a high output impedance will sound better.

some modern super low distortion amps can produce a somewhat harmonically lean, clean-white, antiseptic kind of sound that may be not be favored by listeners used to a more saturated, rich, bloomy type of sound that some tube amps deliver...

Once any frequency response issues are sorted, the differences we hear between amps is the distortion signature. You can think of any amp as having a perfect amplifying aspect and also a distortion aspect thru which the signal travels. That distortion aspect is the 'sonic signature' of the amplifier. SETs have a pronounced 2nd and 3rd harmonic, which masks the higher orders (SETs actually have more higher ordered harmonics than any other kind of amp, but when masked you don't hear them), giving them a lush, smooth sound. Some amps which do not have such pronounced 2nd and 3rd have unmasked higher orders, which contribute to the description in the quote above.

That's not just a subjective thing; these aspects are easily measured; and if the proper distortion spectra results in the amplifier design, no matter if solid state or tube, the amp will be easy to listen to, involving and relaxed. So an SET might have the right distortion signature, but imagine two or three orders of magnitude less. you'd hear more detail with no downside (no brightness or harshness).

I know how hard it can be to understand that this is so- for the last 70 years we've simply had to listen to know if an amplifier was going to be musical and satisfying in our systems. That's a lot to overcome! But also for most of that time, building an amp with enough GBP wasn't possible, and the industry really didn't want the market to know that. Heck, that wasn't too hard to sweep under the carpet because of how hard it is to explain what gain bandwidth product even is!

OK Ralph, so you are ditching everything you have espoused (if not self-promoted) on this forum for twenty years in order to go all-in to self-promote your new Class D amps. Fine. Let history be the judge! Over 60 years time has proven that the basics continue to be valid and that the newest ground breaking production is two steps forward and three steps back. So go ahead and make a fool of yourself. I will sit back and eat popcorn. With extra butter. 

@fsonicsmith

Let history be the judge! Over 60 years time has proven that the basics continue to be valid and that the newest ground breaking production is two steps forward and three steps back. So go ahead and make a fool of yourself. I will sit back and eat popcorn. With extra butter.

I understand new technology is introduced and time marches on, No problem with accepting that. My point is simply everything new is not necessarily better. Can it be?Sure, but it is not a given.

The wonderful thing about audio endeavors is you have the ability to listen to music being reproduced and deciding which truly is better sounding and convincing to you the individual.

I hope that the OP is able at some point to compare his beautiful and timeless (In my humble opinion) VAC Renaissance 70/70 to a modern high NFB circuit design solid state amplifier and draw his own conclusion. Just listen to the music, which amplifier  is the more compelling and promotes more listener engagement and emotion/passion? That’s the better amplifier.

Charles

Technology only moves on one direction.   My ears tell me things are possible today that were not in years past with amplifier technology.  There are some very good older amps but I would have no interest in moving backwards. 

Lancelock mentioned the Altec Lansing 1570B (170 Watt mono). I have a pair of the Altec 1568A (40 Watt mono), also about sixty years old and they sound beautiful.
These Altec theater amps had some of the finest transformers ever put in audio amplifiers but the power supplies were primitive. Tightening up the PS with new, larger electrolytics and poly bypass caps, maybe adding a choke, turned these into some of the finest sounding amplifiers, tube or SS, money can buy -

But not quite up to the level of a (modded) Harman Kardon Citation II (Stereo 60/60), again with superb transformers, probably THE best ever, which I am currently using and which replaced the Altecs.

There’s probably something to be said for vintage Audio Research and Marantz 9’s but those get crazy expensive and I haven’t had them in my system.

I have copious notes on the mods for both the Altec and HK which I’d be pleased to share if you’re interested.

Marc Stager
New York City
https://stagersound.com/silver

I am running a 20 year old BAT VK-60SE that destroys everything I compare it to (that I can afford).  Of course that is kind of the point of this hobby…finding those relatively affordable gems, new or used, that just break the mold for years to come and stand the test of time of musical enjoyment, if not also technical accuracy.  

I recently listened to some vintage Fisher gear, having had a Fisher 400 as a kid but not realizing what I had.  My part-time paycheck replaced it with an Onkyo separates and CD player.  I thought it was broken when I hooked it up…but I digress.

Listening to that amp 35 years later I remembered the lack of extension and warmth, but was floored by the textures, image and musicality, remembering that moment when I realized SS then, as now, just cannot compete with tubes, for me at least.

However, my 20 year old BAT has none of those shortcomings and the qualities in spades.  I only have, for heat issues, a less vintage Ayre SS amp that while very good in its own right and a fantastic, reliable, great sounding amp, is a disappointment every time I turn it on.

I have two pieces of gear that I will never sell: the BAT and my LS-50s.  Not because they are faultless, but because they so fundamentally make the music sing that ‘better’ ceases to be relevant.  Now or in 20 years.

Enjoy your VAC.

My ears tell me things are possible today that were not in years past with amplifier technology. There are some very good older amps but I would have no interest in moving backwards

Precisely my point , use your ears and decide. If you genuinely believe that the new betters the older alternatives then case closed as far as you’re concerned, I get it.

For other fellow music lovers who also listen and compare, their outcome and conclusions may tell them otherwise. The epitome of individuality. No consensus correct or incorrect but rather what sounds best in each unique listener’s case.

Charles

The vintage amplifiers still sound good but parts quality has definitely improved over the years with Capacitors and other low noise parts. IMHO, it's possible to build a superior amplifier now but it will be at a cost!

technological advancement is not always for the better in a subjectively driven, aesthetic pursuit where criteria people care about are highly complex and multi-variate

well worn example of sports/performance cars... new cars are better technologically in so many ways, but are boring to drive, lacks soul, involvement -- computerized/robotic perfect in some ways, as appliances and easy speed machines, but for those seeking thrills, man machine involvement, emotional engagement, development and sharpening of skills, they are sorely lacking

similarly, machines we buy to make music for ourselves to enjoy should, at their best, stir the senses, invigorate the soul, transport our spirits, connect us with beloved artists at the height of their artistry... technology in such devices makes for more choices, an expanse of possible presentations -- but different may/may not be better... we all strive to experience, and decide for ourselves....

@jjss49 

+10 for your well stated comments. 3 weeks ago I attended a classical music performance featuring a cello and piano duet. This past weekend my daughter and I went to a local jazz venue . Both experiences were quite different obviously but what they shared in common was the high degree of emotional involvement and listening joy. Both outings were simply wonderful. 

I believe most of us who love music strive to obtain some reasonable degree of this engagement and the stirring of emotions through our home audio systems (At least that's my objective). Newer audio technology  may certainly have the potential to achieve this goal. Time and listening will tell. 

I just do not buy the idea that by virtue of being the next new thing it  by default is superior to what already exists and is performance proven. I've heard the VAC Renaissance amplifiers and know it is quite capable of providing a highly emotionally engaging music listening experience. High NFB solid state may or may not. Actually listening is the true arbiter for better or worse. 

Charles 

 New is not necessarily better. Remember that it is promoted that way by the audio media to help perpetuate the hobby. That's a fact all hobbies go through fads and it gets promoted that you need this not what we told you ten years ago. Get rid of your old stuff buy new! I love currently the idea of stereo pieces that have upper end sparkle. I have listened to some of the pieces that are written about in that way and thirty years ago things like that were called bright! And we're to be avoided. Now it seems like bright is being promoted is that because the average audiofile has gotten older as the hobby doesn't seems to attract the you g anymore and us old audiofiles are losing our high frequency hearing? That's something to ponder. You see the exact same thing going on in hunting magazines the rifle calibres they promote now compared to the past. All hobbies have this promotion directly for sales. 

The other thing I would ask the original posted are you sure when you send your amp back to be modified it will be better? You might get a surprise and that you don't like the changes. Be careful. 

Regards

so you are ditching everything you have espoused (if not self-promoted) on this forum for twenty years in order to go all-in to self-promote your new Class D amps.

Wow. Did you see me promoting our class D amps here? I simply stated the underlying engineering issue that any designer faces if they wish to advance the art.

I'm not stating anything in conflict with anything I've stated before. You'll notice that our OTLs are zero feedback- that was done because applying enough feedback to avoid brightness and harshness was never possible. Personally, I find harshness and brightness to be the biggest sin audio can commit. So they are zero feedback, class A(2), a single stage of gain, all triode, fully differential and balanced from input to output, and output transformerless. This was done to eliminate as many distortion sources as possible. It worked- the OTLs have dramatically lower distortion than any SET, are obviously more transparent on that account and have garnered a lot of nice reviews and awards in the high end press. So we know they work, as if our ears weren't telling us that:

Precisely my point , use your ears and decide. If you genuinely believe that the new betters the older alternatives then case closed as far as you’re concerned, I get it.

Let’s simplify negative feedback = taking something ( the AC audio signal aka music ) that has ALREADY happened, flip it around out of phase ( that’s the negative part ) and feed it back into the input where something new and unequal is happening ( unless you think sine ways are music )… then apply some critical thinking….

I will point you to this, the Amp I have is zero feedback design.

RENAISSANCE SEVENTY/SEVENTY Mk. III Dual Mono Zero Feedback All Triode Power Amplifier

FWIW. Attached is the PDF manual.

@retiredfarmer Yes, the Mk III updates were in essence the last version of this amp and preamp, so it is improved upon in their design, their finest version of them if you will.

The issue with negative feedback is tied to the maligning of the micro aspects (in time and level) of transient leading edges.

Since our hearing is based upon this area of a signal, this means that, to overstate it a hair..that..100% of our hearing is in the 1-0.5% (and less) of the signal that negative feedback makes a total mess out of.

Linear measurement wise, this small error is meaningless, as mathematical ratios may go, in mathematical weighting and evaluation.

Which has pretty well SQUAT to do with how humans hear. (the given unweighted and disconnected mathematics)

Negative feedback is, generally, a solution to a problem that humans don’t really understand. at least in the idea of book learned electrical and electronic engineers of audio gear. We have to connect the problem and the solution together and that requires an intimate understanding of the problem. the problem, or question, is the REAL specifics the REAL internal meat and neural and cranial aspects of how humans hear, in the minute and total sum details.

Until then, these methods of making audio, like class D or negative feedback will continue to be the ill ought out abominations that they are. Like idiots on gobos and crutches, trying to run a world class 100 meter dash. Bad attempt, bad understanding, wrongheaded result of dubious value.. looks good on paper, though. works like a bear dancing.

bears don’t dance, they hit the sweet spot in our minds that sees the motions as being akin to dancing so we mentally place a dancing mental envelope of interpretation over the lurching about.

With bad audio we are dealing with the aural equivalent of Pareidolia getting in the way, where we create the shape of the signal in our minds, when it’s actual clarity is not truly there in the most perfect shape it could be. We are wired to fill in, via precognition of all our history in aural ingestion and interpretation.

THAT..is /class D and high negative feedback, in a nutshell.

Some of us can hear past it and recognize these inbuilt filters and correct for them. we can see waldo, aurally.

Some cannot or they feel they see waldo well enough that he’s actually there.

good audio reproduction allows a person to put the mental aural mind scrunching and efforts away, and just listen in a totally relaxed manner to the beauty of it all.

THIS is what Ralph is talking about when he talks about what the atmosphere amps are better at (and others are also better at)

Its the difference between an aware and thinking audiophile getting off on music. Or,on the other side, the linear mind side...getting off and solving a ’puzzle’ of signal recognition and interpretation, which is work. fun for some, but it’s work, hard work. hard, edgy screechy work, work upon a signal that is purposely damaged to make some aspects more aurally obvious, or separated from the whole.. And i hate that sound, like all sane thinking people should. It is horrible and anti-music.

Since we are all individuals with different learning curves, different libraries of internal data, and individual different & differentiated meat packages we are wrapped in...this is not a place where we can lay down a black and white law that covers all potentials.

Generally...the less a person understands all of this, the more the monkey inside senses danger (unknowns!), and henceforth desires a perfect black and white answer to these complexities. So, to self protect, it sits, claws out, in fighting positon..and lays a yes/no black/white beating down on the complexities it does not cognate or understand ...and lays down beatings on audio and music fans, fans that that tell them they’ve got it completely backward.

so, to overstate it slightly to edge enhance the visual on this so the general shape of it can be seen more clearly:

This is what partially encompasses my dislike, my honest and well thought out dislike of the premise and actions of the overall shaped thing called ASR. It’s deep premise is as dumb as a bag of hammers, it is missing the real argument and question, entirely. It is insistent on hanging witches, witches of it’s own creation, witches that don’t exist. It fails to understand the entirety of it’s own core question and answer set.

It also explains the haters and the detractors here on this forum.

No written word set is perfect nor entirely accurate, so don’t take it personally or seek to chase down some minor error in form or whatnot, in with I write here. That would only amply show everyone who is reading and can grok it all...one’s lack of understanding of the issue or the nature of functional discourse.

New technology sets the bar for what is possible at the various price points. That of course does not mean all new technology is better. Avoid generalizations always.

I would advise against trying to simplify technical issues like negative feedback.  It won’t work.   The devil is always in the details and how well the experts do things.  That’s why we pay them to design and build things for us. 

Negative feedback does not work, in the final aspect of looking for perfection in it, in looking for perfection that is reasonably attainable (compared to other possible solutions).

Positive feedback might, if it is programmed correctly. A mighty big if, if there ever was one.

Problem is, that in an entire playback chain, that positive feedback aspect has to be carefully programmed. But some impossibilities remain, or at least seem impossible. Chaos/’infinite variation’ aspects, at least with our normal level of ability to unwind their complexities.

Negative feedback, one might say, is the simplified method of getting past those potentials in error within executing positive feedback. One that fails to take on the fundamental. Rather that it is ’clever’ and sidesteps it all, instead.

I did do a design where I combined negative feedback with a specifically shaped interference in the given amplified signal. It tends to sound like the best of both worlds. People remarked that they’d never heard anything like it before.

An example of this sort of area of thinking is found in Jim Strickland’s Accoustat TN amplifier circuit. It looks kinda dumb at first glance. The trick is that it is dynamically active.  It is transient wave shaping, in it's feedback effects, in the realm of time and level.

Case in point. 

You're welcome.

Irony is a must, in all things that are observed in moderation.

Take..er.. your 'give and take', in it's norms. It's ambiguity, and shortness, for some, is designed from the ground up, to speak in ways of inflicted harm, via the least words possible. Trolling without seemingly being trolling. I see you.

It has become an interesting thread. Two people are talking about negative feedback. One clearly understands the topic and appears to be able to talk about it in great length. The other appears to talk at great length. It is up to the reader to decide who is correct. I enjoy both, but for different reasons.

I did not cover the aspect of trailing layers of various odd ordered harmonic distortion patterns, as I try to take care of that when I'm messing with an amplifier execution, at the fundamental level. It is a huge part of the coloration, as Ralph says. But so is the other aspect that I speak of. Have to be careful, though, or we'll be delving into some thing about big boxes on cables and an infinity of poles of articulation.😉

Let’s simplify negative feedback = taking something ( the AC audio signal aka music ) that has ALREADY happened, flip it around out of phase ( that’s the negative part ) and feed it back into the input where something new and unequal is happening ( unless you think sine ways are music )… then apply some critical thinking….

This statement is false. Its based on the idea that there is a time delay between input and output. What actually happens is there are frequency poles in the amplifier that cause phase shift; on an oscilloscope this appears as a time deviation if you are measuring in the range of the phase shift.

Filter theory tells us that there will be phase shift at some high frequency (in an amplifier, the high frequency roll off will be on a 6dB per octave slop initially; this will impose phase shift to 1/10th the cutoff frequency). As you increase frequency, eventually the phase shift is so acute that the feedback becomes negative instead of positive, and the amp goes into oscillation. Norman Crowhurst was writing about this 65 years ago; none of this is controversial. When the amp goes into oscillation, it can be said that its phase margin has been exceeded.

http://www.tubebooks.org/Books/crowhurst_basic_3.pdf

(link above for those interested in how this really works)

This explains what is really happening and is not some sort of pseudo neo-science.

So if one has been paying attention, one should see what the problem is with feedback in traditional amplifiers (which includes all tube amps). You have an output transformer in most cases, and it causes a fair amount of phase shift, often inside the audio passband! As a result, it poses a limit on how much feedback can be used, and is a guarantee that the feedback will cause harshness and brightness as a result (I already explained why).

Futterman applied 60dB of feedback in his OTLs, but the problem he was up against was not a lot different: his design not only had significant poles in the circuit design, but he also had overall insufficient Gain Bandwidth Product. This means that feedback was decreasing at higher frequencies and so harshness was the result. Because of the frequency poles oscillation was an ever-present danger as well.

Bruno Putzeys wrote a wonderful article on feedback.

https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf

It explains much of what I’ve been talking about here in greater detail. Don’t worry if you can’t follow the math 😁 You’ll note that he mentions Peter Baxandall’s writings of how feedback imposes distortion of its own, reflecting Norman Crowhurst’s observations (and explanations) of that from 20 years earlier. Those individuals never got the chance to play with an amp with sufficient bandwidth and loop gain! Its precisely that (sufficient bandwidth and loop gain) which is why an older amp might not keep up with a state of the art design (although it might easily keep up with new amps that are rehashed circuits from earlier decades).

Thank you @atmasphere , skimmed the linearaudio link, will delve in later. Looks like it will not be that hard to follow.

In addition to what you write, is not the negative in negative feedback, simple because it is subtracted?

In addition to what you write, is not the negative in negative feedback, simple because it is subtracted?

If I get your meaning, probably not. In most amplifiers the feedback is applied to a node that has non-linearities, so often feedback signal itself contains distortion not present at the output! For example in a typical solid state amp, the input circuit is a differential amplifier. One of its inputs (differential amplifiers have two, one inverted and the other non-inverted) takes the signal. The other takes the feedback. But the device (transistor) isn't perfectly linear... Of course, if you applied enough feedback, you could overcome this issue...

No I meant in a much more simple fashion, i.e. a portion of the output is subtracted from the input. Literally negative. It would technically be out of phase but that is by definition. 

When @teo_audio writes positive feedback, does he really mean feed forward?

@atmasphere 

Your participation and patience on this Forum is something for which I am truly grateful. Comments from you are always illuminating and helpful.

Thank you.

No I meant in a much more simple fashion, i.e. a portion of the output is subtracted from the input. Literally negative. It would technically be out of phase but that is by definition. 

Yes- we use a resistive divider network to do that in our smaller OTLs (we run 2dB of feedback in the M-60). You either do it that way or thru an active device, such as a tube's cathode while the input signal is applied to the grid.

But the feedback network itself can be simple or complex, depending on (...how well its designed...) the expectations for it, such as keeping unwanted frequencies out of the loop. For example in a class D amp that is self-oscillating, the feedback network defines the oscillation frequency (known as the 'oscillation criteria') since so much feedback is applied that the amp goes into oscillation as soon as its turned on; the amp then uses the oscillation as the switching frequency. That network can be a 4th or 5th order loop with 6 or 7 variables; for that you'll need a computer to sort it out.

What this means is its possible to build a solid state amp that is every bit as smooth in the mids and highs as the best tube amps and leave nothing on the table in terms of detail, sound stage and the like, in such a way that vintage amps simply cannot compete (not that they sound bad, just they don’t sound as good). This is one of those things that is easy to hear and easy to measure.

Bruno Putzeys wrote a wonderful article on feedback.

For example in a class D amp that is self-oscillating,

C'mon folks, apply a little critical reading and thinking skills. Read and see what is clearly between the lines. While I had always admired Ralph and thanked him for his participation here (though disagreeing with his continued insistence that higher cartridge loading is always best unless RFI interferes and that correspondingly, RFI is the chief factor upon which cartridge loading should be chosen), there is clearly a theme here towards promotion of his Class D amps. I have to wonder how a customer of Atma-Sphere who just paid 20K+ for a pair of the MA-1's a month ago must feel when it's principal proclaims his own product to be by nature inferior to his new solid state alternative. 

And I am also surprised and even angry at myself to only now notice that Ralph is so reliant upon that which can be measured. 

Burn him at the stake!!!!   I am really getting a kick out of this place.

I was curious, so I tried a search. "Class D" and then found I could filter by user, so I filtered for atmasphere. It appears that atmasphere has been communicating about their class D amplifier for almost 5 years. It could be longer but I got bored of searching.

I have worked in semiconductors and batteries. Everything new we release is better and better rendering even last years products effectively obsolete. I find this a strange thing to complain about. When I read atmasphere's other posts in this thread, I would be happy he does rely on measurements. He seems to have a handle on how those measurements will make his product sound. How can that not be a good thing?  This is audio. I don't think accusing people of audiophile heresy is productive.

You are right...

When people dont understand something they search for simplistic  explanation and they mob together...

I don't think accusing people of audiophile heresy is productive.

 

@fsonicsmith

And I am also surprised and even angry at myself to only now notice that Ralph is so reliant upon that which can be measured

Ralph is an accomplished electrical engineer and also a successful audio electronics manufacturer. I certainly can appreciate his reliance and support of formal measurements as it simply reflects his training and background.

In addition I find his explanation of NFB as utilized in the manner he describes proper application. It is logical and coherent. My primary objection is the assumption that this approach is inherently going to result in a better sounding amplifier than the OP’s VAC Renaissance amplifier. A false assumption in my opinion. A listener would have to compare them in a direct A/B setting.

I just don’t buy the notion that new technology is without debate always the better performing/sounding choice. It has to be confirmed under real world listening/audition  conditions not just in theory.

Charles

Well stated Charles.

A listener would have to compare them in a direct A/B setting.

i think so also...

At the end acoustic/psycho-acoustic experience in a room decide what will be our choices, because nevermind the theoretical level of improvement, no ears and no room are exactly the same ...

The law of hearing are the same but the ears differ...The needs of people differ too...

And if technoloy improve always with time, there is a plateau of maturity where new technological improvement rival other different technological  advantages improvement with different trade-off...

Well this is the only modern amp that I like better than what I have. 

https://dandagostino.com/products/relentless-amplifier

The significant sort of modern advance is Class D amplification.  The better designs are pretty much indistinguishable, to me anyway, from other high end solid state designs.  But, where one does not need a whole lot of power, my preference is for low-powered tube amps.  I find that the better low-powered tube amps (roughly 40 watts or less)  to be more engaging and lively sounding at lower volume levels than solid state amps (you have to crank the volume up just a bit more with solid state to feel the music come alive).  I also think that such tube amps have a more natural sounding attack to the note (less of an artificial sounding "edge"). 

The amps I own include a parallel single-ended 2a3 amp (Audio Note Kageki), and a pushpull 349 amp built in Italy by Aldo D'Urso (sort of a replica of a Western Electric 133 amp using original Western Electric transformers and other vintage parts).  The parallel 2a3 amp puts out something like 6.5 watts, the 349 amp something around 5.5 watts.

My personal preference is for low-powered triode tubes (e.g., 2a3, 45) in either single-ended operation or pushpull, and certain pentode/tetrode tubes (KT-66, 6L6, 350B, 349) in pushpull operation.  I tend to dislike high powered tube amps that use multiple higher output tube types--the sound becomes hard and has a "glare" that I find a bit annoying.

I really like certain OTL amps as well.  They have an "immediacy" and sound extremely exciting and dynamic compared to most other amp types.  Some are operationally fussy (not the Atmasphere amps), and are a bit scary to me because I have speakers that are close to irreplaceable.  One of the best amps I've ever heard is a custom-made OTL amp.  

As for solid state amps, the ones I've heard that I particularly liked have also been low-powered, specifically the First Watt J-2 (borrowed from a friend for two weeks) and their SIT amp (heard in a friend's system).  These have a slight bit of an artificial edge to the attack of a note, but, they don't sound as dead and unengaging as most other solid state amps.  I also like some Ayre amps because they sound relatively relaxed without sounding dead; if you need more power, they are a good choice. 

When @teo_audio writes positive feedback, does he really mean feed forward?

Technically (as in: labeled for least potential in confusion), feed forward, yes.

@larryi 

Great post. I wish you could hear my Ampsandsound Nautilus which is a modern recreation of the HK Citation II. It puts out 8 watts of SE triode. The amp is overbuilt to the extreme. It is perhaps half the size of my ARC Ref 80S and yet weighs the same. I wish you could hear it not because I have any reason to believe it is any better or even as good as your low powered amps but because your impression would be interesting given your library of knowledge and amps. 

@fsonicsmith

Thank you for bringing to my attention the Ampsandsound gear, a brand I do not know, until now.  I looked at their website and their design and build look really interesting.  I love amps built using turret boards.  The layout of their wiring is extraordinarily neat and uncluttered and it appears to be extremely easy to service--nothing has to be disassembled to get to a component.  I like the way that all wires that have to pass through the chassis or internal walls goes through a high quality passthrough grommet.  The only giveaway that it is not a truly old school build is the use of plastic ties to hold the wires together.   

C’mon folks, apply a little critical reading and thinking skills. Read and see what is clearly between the lines. While I had always admired Ralph and thanked him for his participation here (though disagreeing with his continued insistence that higher cartridge loading is always best unless RFI interferes and that correspondingly, RFI is the chief factor upon which cartridge loading should be chosen), there is clearly a theme here towards promotion of his Class D amps. I have to wonder how a customer of Atma-Sphere who just paid 20K+ for a pair of the MA-1’s a month ago must feel when it’s principal proclaims his own product to be by nature inferior to his new solid state alternative.

And I am also surprised and even angry at myself to only now notice that Ralph is so reliant upon that which can be measured.

:) Critical thinking. I like that: far too little of that going on these days; people have taught themselves to disable their critical thinking. Dietrich Bonhoeffer wrote an interesting paper (which later got him killed) regarding this topic.

Some loudspeakers are not meant to be driven by an amplifier that behaves as a voltage source. ESLs are a good example. For those, tube amps remain the more viable alternative (and just for the record, the last set of MA-1s, which did ship about a month ago, are in use with a set of Sound Labs; something our class D simply can’t make the power to drive because of the impedance. So to my understanding, he feels pretty good.)

Regarding the cartridge RFI thing, that’s easy enough to demonstrate:

http://www.hagtech.com/loading.html

If you have a one meter phono cable, 20pf/foot is typical. find the inductance value of your LOMC cartridge and drop the values into the calculator. You’ll find that the resonant peak is in the RF range. This calculator is based on simple math that comes from electronics 101 in the first week.

Regarding our Class D amplifier, you brought that up, not me. Again, I was addressing the original question, which, again, the answer is that there are semiconductor devices now that didn’t exist 25 years ago, allowing designers to build amps that are actually successful at getting rid of audible distortion (harshness and brightness being an example that might measure quite low on the bench), whereas prior to that time, getting rid of harshness in solid state amps was done with a simple technique called ’lying’.

That lying is why for the last 60 years audiophiles have had to take equipment home to find out if it sounded OK in their system. Its going to take a while to overcome that learned behavior! the first and hardest thing will be to convince people this is all real. As audiophiles we’ve been lied to for so long we take it as rote.

Regarding measurements: One of the problems that many audiophiles have is that the spec sheet seems counterintuitive; amps with lower distortion often sound worse than those with significantly higher distortion. This is because the ear is sensitive to higher ordered harmonics and the harmonics are not ’weighted’ on spec sheets (and the amps with higher distortion are often tube amps with a lot of 2nd and 3rd harmonic). Amps with low distortion figures often have unmasked higher ordered harmonic content at low levels, but the ear is keenly sensitive to these harmonics as it uses them to sense sound pressure, so has a 130dB range to support!

But we can measure what’s important! And reliably predict what the amp will sound like based on those measurements. However most of these measurements rarely if ever show up on spec sheets. Here they are:

1) distortion vs frequency. If rising at all past 1KHz, expect brightness; I explained why earlier.

2) distortion spectra. To mask distortion you have two avenues, either get the distortion product well below -100dB or mask the higher orders with a more prodigious 2nd or 3rd harmonic. SETs use the 2nd harmonic, our OTLs use the 3rd. The distortion spectra should remain consistent at all frequencies, not just 100Hz or 1KHz! FWIW zero feedback tube amps can do this last bit quite well.

3) distortion spectra at -6dB of full power (you never see this one). It should be consistent with the 1 Watt spectra. SETs often fail this test; higher ordered harmonics appear in their output at this level (usually on transients) causing the amplifier to sound ’dynamic’. I’ve found that when audiophiles discuss ’dynamics’, for at least 80% of the time, the word ’distortion’ can be substituted for ’dynamics’ without changing the meaning of the conversation.

If the amplifier is well behaved in these regards it will sound smooth and musical; the lower the distortion the more transparent the amp will be because distortion obscures detail. This is why I don’t like SETs because they often have several orders of magnitude more distortion, causing them to lack detail. Detail does not have to be associated with brightness although it often is because typical solid state amps that are low in distortion are often bright and harsh, although they are at the same time more detailed. You know you’re making progress when the sound is smoother and more detailed both at the same time!

Measurements are really really helpful if the designer understands the how the ear perceives distortion. IOW you can design the amp to work with the human ear rather than to look good on paper; if you really know what you’re doing you can achieve both!

Thanks...

You are very clear...

When it comes to amps, there seem to be a plethora of folks who like a specific sound. Some will call that sound ’distortion’, others will call it ’neutrality’ and still others will call it ’transparency’. Tube amps have a specific ’sound’, that sound is generally more pleasant to the human ear than some of the typical ss Class D sound that most folks associate with the class. OTOH, there are folks who prefer this very sound that others decry. At the end of the day, I believe it is the ’flavor’ of the amp sound that we choose...and the appeal to not only our pocket book, but also our aesthetics. Most amp manufacturer’s know this...and design accordingly.

Another question is: has the basic circuit of the tube or ss amp design changed that significantly over the years to call it a total re-design? That is a question for the more technically advanced here.