Nelson Pass: Circuit Topology and the End of Science

Nelson Pass is a consummate engineer, but he got his start in physics, earning a bachelor's degree from UC Davis. As he worked on his degree, he was already an audio designer, focusing on loudspeakers—great training for a designer of audio amplifiers. Soon, in 1974, he cofounded Threshold Audio with René Besne, of audio and folk-dancing fame; their goal was to build electronics, partly because the field is less competitive—it's harder than building speakers. As he told Thomas J. Norton in "Simple Sounds Better," an interview in the November 1991 issue of Stereophile, Pass created one of the first high-power class-A amplifiers: the Threshold 800A. He'd dreamed up its key technical approaches in the back of a bus, on his way to visit a cave. Also in 1991 he founded Pass Labs, which focuses on high-power transistor designs, and in 2004 he started a second company, First Watt, to produce and market some of his more interesting experiments, mostly in low-power amplification, using an unusually wide variety of solid-state devices.

I wanted to know more about Pass's approach to amplifier design, so we had a chat by e-mail.

Jim Austin: Do you own any tube amps?

Nelson Pass: I have a couple of commercial EL34 SET [single-ended-triode] and P-P pentode amplifiers—nothing special—and a pair of point-to-point pentodes that Wayne [Colburn] made for me (footnote 1). The SET is interesting because it sounds a lot like the [First Watt] SIT-1 and SIT-2 [power amplifiers], but has more noise and lacks the bandwidth. It's nice to take a listen to them now and then. I enjoy listening to differences.

Austin: You've chosen to work with semiconductor devices, not tubes. Yet you've expressed appreciation for tubes, and in some of your designs you seem to be working to mimic the sound of tubes. Please explain.

Pass: Fundamentally, what interests me most about amplifiers are the differences in sound created by different topologies and the characteristics of the active gain devices. There are few things I enjoy so much as to contemplate the specific (and complex) characteristics of the many transistors (or tubes) and how they might fit into an amplifier to deliver a sound which has a particular signature. Toward that end, I like simple circuits, partly because well-designed, simple amplifiers tend to sound better, and also because they bring the part's personality into sharper relief.

This relates nicely to tubes, in that the economics of tube circuits enforces a discipline of simplicity, where it is not convenient to achieve quality by throwing lots [of] parts and feedback at the problem. You will not see 50 tubes and 80dB of negative feedback under the hood of any tube amplifier.

However, most of the best approaches to tube design are well mapped already. Not so much with solid-state, where the art of simple has been somewhat neglected and where there is a vast array [of] new and interesting parts. That's why I choose solid-state.

Also important, it's relatively easy to take ideas in simple solid-state, and build them up and play with them in short order. It's much quicker to try lots of variations and refine the design. It's much easier to get some built, and have other people listen to them as well.

For example, here's a solid-state circuit you will not have seen, which I showed at the Burning Amp Festival [BAF] last month (fig.1):

917pass.schem.jpg

Fig.1 Nelson Pass's self-biased, class-A, push-pull output stage using a depletion-mode, N-channel power JFET coupled to an enhancement-mode P-channel MOSFET.

It's a self-biased, class-A, push-pull output stage that uses a depletion-mode, N-channel power JFET coupled to an enhancement-mode P-channel MOSFET. No bias circuit, doesn't need degeneration, has built-in temperature compensations. Works great. How's that for simple? I'll make a product out of it (or a kit for DIYers) next year.

So I don't have any problems with tubes. It's just that, with the limited number of years I have to work with, I need to have some measure of focus.

Tube design has plenty to say to solid-state, although I don't see most designers paying that much attention. On numerous of my projects, I have revived old ideas and added some of my own. My favorite transistors are JFETs, MOSFETs, and SITs, all of which are analogs of tubes. The JFETs and MOSFETs are a lot like pentodes, and the SIT, a special form of JFET, is best modeled as a triode (footnote 2).

I haven't designed a bipolar transistor amplifier in 27 years—[my work during] the previous 22 years was adequate, I think—so you could fairly say that I replicate tubes at least some of the time.

The other fundamental thing—number 2—is that I am centrally aware that all this is just entertainment, mine and yours. The objective needs of amplifier users are largely solved on a practical level, and as [Marshall] McLuhan perceptively noted, when that happens, we turn our technology into art. For me, the art lies in making simple, unusual amplifiers that sound great and measure fairly well. They aren't for everyone, but if they appeal to even a narrow segment of audiophiles, I'm perfectly happy. I'm equally happy if they are reliable.

Austin: You say that your favorite transistors are JFETs, MOSFETs, and SITs. Would you say that each of these classes of transistor has its own sound, which you can extract with appropriate implementation?

Pass: The JFETs and MOSFETs have a lot in common, generally a pentode characteristic, and with a few exceptions, JFETs are relegated to input-stage and line-level buffer types of use. Those exceptions would be The Beast with a Thousand JFETs, and of course the power JFETs I have in Silicon Carbide (SiC) from USiC [United Silicon Carbide Inc.] and the now-defunct SemiSouth (footnote 3).

All of these have their specialty, but you can't characterize the sound generally, as each has strengths and weaknesses, which become important in different modes of usage. FETs [field-effect transistors] as a group are often described as more tube-like than bipolar transistors, and that is a reasonable sort of generalization, but too broad to be actually useful. Bipolars have their own character, but the same sort of thing applies about use. For the past 27 years I have dealt in FETs as a matter of personal preference, but bipolars still make it into some of the circuits, usually as cascode transistors.

The SITs are a special breed of JFET that have a triode-like characteristic, not pentode like the other FETs. This gives rise to some interesting performances, the most entertaining being simulations of SET amplifiers without the output transformers, and really good, larger, push-pull power amps.

Austin: You say you haven't designed a new bipolar transistor amp in 27 years. Is that because you don't like the sound of bipolars, or is it because you felt you'd done all you could with them?

Pass: Mostly because I was done, but I also wanted to head in a different direction with devices and the sound.

Austin: Apart from the choice of devices and circuit topology, what else matters in amplifier design? Layout? Boutique parts?

Pass: People may not appreciate how many potential options a designer has. Think of it this way: There are three ways to use a three-pin device. For a FET, this would be Common Drain (a voltage follower), Common Gate (voltage gain with unity current gain), and Common Source (voltage and current gain). All transistor and tube devices have the same list, but the pin names are different.

For a thumbnail calculation, [if] we go to the Digi-Key catalog and look under power MOSFETs powerful enough to use in an output stage, we see about 3000 easily obtained parts. Under bipolar devices we see about 600 such parts. So the permutations available for a single stage (in this case, output stage) start at about 10,000 for a single-device, single-ended circuit. This sort of number becomes squared for a two-stage amplifier, and cubed for three-stage amplifier, and so here we are at maybe a trillion possibilities. And we still haven't decided which stages are biased by how much (a continuum of values), or how much each device is allowed to contribute to gain and by what technique. And so on.

917pass.einstein.jpg

Rather than becoming overwhelmed by the permutations, the author, artist, or designer—because writing and painting, for example, offer the same endless range of possibilities—can borrow from the work of predecessors, refining technique and hopefully eventually transcending those influences and "finding their own voice." I refer you to Harold Bloom's The Anxiety of Influence: A Theory of Poetry (footnote 4)—or if you just want a great book to read, John Horgan's The End of Science: Facing the Limits of Knowledge in the Twilight of the Scientific Age is back in print again after 20 years (footnote 5).



Footnote 1: Wayne Colburn is a designer and a member of the core Pass Labs team. He first joined Nelson Pass in 1994, at Pass Labs, after answering an ad in Audio Amateur seeking a "wizard's assistant," as John Atkinson wrote in his review of the Pass Labs XP-30 preamplifier in the April 2013 issue. Colburn is largely responsible for the design of Pass Labs' preamplifiers and integrated amplifiers.

Footnote 2: Because of its vertical construction, the static induction transistor (SIT) was known in the late 1970s as the vertical field effect transistor (VFET).

Footnote 3: See, for example, the First Watt J2, which was reviewed by Herb Reichert in October 2016.

Footnote 4: In this book, literary critic Harold Bloom argues that a poet's influences can cause her or his work to be derivative, and outlines ways poets can avoid the resulting "anxiety" and create more original work.

Footnote 5: Similar to Pass's comment that "The objective needs of amplifier users are largely solved on a practical level," The End of Science, first published in 1996, posits that most of science's big ideas—evolution by natural selection, the big bang, relativity, quantum mechanics—are in place, and that in the future there will be far fewer scientific "revolutions or revelations." The book was widely criticized, including by prominent scientists, but in an essay in Scientific American, Horgan said, "hell, no," he hasn't changed his mind.

ARTICLE CONTENTS

COMMENTS
tonykaz's picture

Why do so many of our Audiophile writers own Pass stuff?

I wen't back to Herb Reichert's review of a First Watt, phew x 2!!, Mr.HR does a darn good job of explaining it.

Still, it's gonna take a hefty bundle of cash and a couple of decades experience for regular Audiophiles to find a way to connect the dots the way HR and Steve Gutenberg seem to have done for themselves when these leaps of faith cost in the range of $8,000 a pop.

We need Audiophile Salons in every City, for gods sake!

Am I yearning for the good ole 1980s?

Tony in Michigan

Ellis Craig's picture

He talks about amplifiers that measure well and do not sound good. This idea is talked about often for years in audio publications but never with examples. What are examples of recent amplifiers that measure well and do not sound good?

Anton's picture

The ones that sound best seem to find ways of introducing second-order harmonic distortion.

Amps that measure 'better,' then, would not 'sound' as good.

Mr. Pass mentioned some very cool second order stuff in his interview.

Second order distortion seems to add a certain frisson to the sound of recorded music that many people enjoy.

I am saving up for some Pass amps, but I biamp, so it's gonna be a while!

Ellis Craig's picture

If the artist wants 2nd order distortion they can add it themselves, they do not need the amplifier manufacturer to add it.

Anton's picture

Audiophiles aren't the artists, we are the audience, and some in the audience seem to prefer a little second order stuff to create a sensation they like.

As consumers, we can do whatever we like and buy whatever floats our boats!

Hence, different sounding amps with different properties for different audiophiles.

Ellis Craig's picture

Yes what you like is your business but I would think if 2nd order distortion truly sounded so good artists would add it theemselves, turn up the gain on the guitar and bass amps, use Aphex aural exciter etc. It is marketing genious, make an amplifier worse and sell it for more, say it is less pinched, more musical and it gets good reviews and audiophiles buy.

Anton's picture

Hell, artists add intentional distortions all the time. You think they don't?

Try any electric guitar, amp, effects pedals, etc.

Anything but a pure tone is, technically, a distortion.

It's distortion that makes the musical experience. Or, play perfect tone music, if that's your goal for avoiding distortions.

Add on top of that...as a consumer, I receive an imperfect product. There is no perfect playback system. So, a consumer is free to play around with how the sound is produced so that it pleases the listener.

Ellis Craig's picture

Obviously musicians sometimes add distortion which is why I listed methods they use to do it. You think anything other than sine wave is distortion? Wrong, you confuse natural harmonics with distortion which is ADDITION to the natural harmonics. Distortion makes the musical experience? Adding pickup and Marshall amp to live violin would make the Bach Chaconne better? That is a fatuous comment, more evidence of high end audio absurdity

Anton's picture

If you ponder it, for a live instrument, the original source creates a sound, which has harmonics, overtones, etc...and that totality is somewhat captured by a microphone.

Then the signal is stored for us and we play it.

Our speakers make sounds...which would now create more harmonics, overtones, etc.

It's amazing we can tell it's even Miles Davis or Ella Fitzgerald!

The very act of trying to recreate a sound, creates a different sound.

So, if someone likes this done with a little added second order harmonic distortion, what is really harmed?

There is no such thing as 'true fidelity.'

If you think Hi Fi is absurd, fine.
It is.

My Hi Fi is absurd, as is yours.

Taking it seriously is the absurdity here. If you insist there is only your way of looking at it, then see you at Kingdom Hall! ;-D

You seem like you are mad at Hi Fi.

mrkaic's picture

You are right about audio absurdity. Many audiophiles don't understand basic physics and electrical engineering. They will argue forever about how good the second order distortion sounds, while likely not even knowing what the term means.

Anton's picture

If it makes an audiophile's toe tap, what is it to you?

You weird audio haters who travel the vast internet universe trying to work out your issues are an amazing bunch.

Your pleasure is evangelizing the evils of practicing your hobby in an heretical manner?

Is there an app you can download for getting a life?

So, you have an interview with a renowned amp designer, and you are compelled to save us from his opinions?

Who should we trust, you, or Nelson Pass?

I say neither, but you won't allow us to trust our own ears, so, I will go with Mr. Pass.

Glotz's picture

Is yourself. No matter what proof, what examples, you are still lost to your own brand of ideals.

If you do not try to see the other side, and do your own research, we really should not include you in the discussion, as you are unwilling to see the facts and examples that prove your assertions false.

tonykaz's picture

What does recalcitrant mean?

I won't care which authority you choose to quote, I maintain the 'right' to not to accept it.

Tony in Michigan

JL77's picture

One example are video-grade amplifier ICs. Audio slew, THD, IMD, FR, phase, etc., measures state-of-the-art. But they can sound pinched, unmusical.

Ellis Craig's picture

Is there a specific example of a high end audio amplifier that uses video grade ICs? Is there evidence they sound pinched, unmusical? Can you provide evidence or otherwise why should this not be considered hearsay or maybe just made up.

mrkaic's picture

Great job, thank you for pressing the point. It is quite clear that there is no example of a bad sounding amplifier with good measurements.

Glotz's picture

Your assumptions (and lack of effort to find examples) are getting tedious. The Croft integrated review.

There are several others, but I am not doing your homework, as you have proven to be quite lax in finding your own argument support.

mrkaic's picture

...Croft Integrated measures poorly, but Art Dudley claims that it sounds good (at least the review that I found in the Stereophile says so). Ellis and I were asking for the opposite: an amplifier that measures well but sounds bad. Sorry, but you have not actually done my homework.

Have you been a bit lax in finding your evidential support? :))

Glotz's picture

Why is that you're so lazy that you can't provide your own basis for your arguments? I put it to you to come up with the proof for your false theories and divisive blathering.

Is the reason you're just a troll and you enjoy this crap?

There isn't even a middle ground for you. Despite the olive branch yesterday, I will ignore you moving forward.

mrkaic's picture

My friend, thank you for the olive branch. No hard feelings.

Anton's picture

This thread will sink into the sunset, but it was good fun.

mrkaic's picture

Yes, we need to continue this over some beer & some handy foods.

Wish everyone a nice Labor Day weekend.

dalethorn's picture

Various amps I've had sound a little different from each other, but I couldn't be sure (short of massive research and testing) whether those differences were inherent to the amps' qualities, or because of how they interfaced with speakers and headphones. But then one day I got a tube amp, and who knows - maybe I was just incredibly lucky in what I used it with, but it had a very smooth liquid sound and a very nice open soundstage.

Glotz's picture

See the AD review.

Glotz's picture

There was a mention in the last article that they don't review any product that doesn't sound 'good', regardless of what they measure. It's a waste of space... much like everything here in this post.

Why didn't anyone talk about the subject of this article, Nelson Pass? I feel disgusted that we let trolls devolve the post once again.

Great interview Jim, nonetheless. I read it several times.

JimAustin's picture

Thanks Glotz. Fun to do.

stereoGoodness's picture

The most salient example of such amplifiers in recent years was the Halcro amplifiers. After fulsome praise of the Halcro amplifiers in Stereophile (including in John Atkinson's measurements discussions), the amplifiers did not sell. Consensus among audiophiles was that the Halcro amplifiers, despite their superior measurements, sounded too dry.

JL77's picture

Ellis, that's our experience. YMMV.

prof's picture

Ellis, that's our experience.

Experience with ... ?

I think Ellis was asking for an example of an amplifier that measures well, but that you experienced as "pinched, unmusical."

It would be quite informative to have an actual example in mind, when discussing this.

Archimago's picture

Yup. Excellent comment and question Ellis.

I've been asking the same question in various forums and in various ways over the years. And yet have seen no good answer either.

Yes, we can all accept the fact that human perception is nuanced and idiosyncratic such that we can accept a wide range of deviation from clean, undistorted reproduction to sound good; fantastic even!

But in regards to high *fidelity* - that is, a device that actually will amplify the source it's fed *faithfully* with minimal change, it would certainly be nice to know what some people are referring to when they feel that modern measurements are somehow missing something of significant importance!

Without some reasonably concrete example, we'll just be running circles around mere opinion and words, bringing us no closer to facts. And ultimately, if nobody can come up with a good example, then perhaps we should dispense with the concept of "measures well, but doesn't sound good" as just another audiophile myth among so many others. (Or perhaps a statement that might have been true decades ago but no longer of relevance these days.)

Anton's picture

Have you ever, even one time, been fooled by any hi-fi system into thinking you were in the presence of real live music?

There are no facts, we are creating pleasant simulations. At best, a simulacrum.

What is it you want fidelity to, a flawed process?

Why?

Some people prefer certain distortion patterns because a distortion of a flawed signal seems more pleasingly "alive" than a faithful copy of an imperfect representation.

There isn't any objective musical truth. You can't be made to think you are sitting in the seventh row of Carnegie Hall for a concert by even the highest "fidelity" system. We are all simply playing around with the crudest of tools, so you play with your crayons and mind your path to enjoyment and
let others color how they want.

You proselytizing evangelical objectivists have dishonest goals. You simply want other audiophiles to be as unhappy as you are. No, thanks.

mrkaic's picture

If you like your distortion you can keep it. Nobody cares. But please stop calling highly distorting "audiophile" gear "high fidelity". It might be high price, but high fidelity it is not.

So called audiophiles should honestly admit that they don't like fidelity. That would be a good start. Then we could start separating buyers of audio gear into low fidelity lowing "audiophiles" and high fidelity lowing listeners of music who refuse to live a musical lie.

Anton's picture

Some audiophiles may not want to settle for faithful reproduction of crap.

Just as someone may wish to change a recipe.

There is no requirement for absolute adherence to something that is flawed to begin with.

The same audiophiles would tell you to stop with the "reproduce the exact signal on the recording."

Your goal may be to stay faithful to a signal.

Their goal is to create the illusion of live music.

Maybe the audiophiles who bedevil you so are actually into 'higher fidelity' than you are.

0.0000001% 'distortion' for you, toe tapping and dancing for them.

The hobby can support both, but one side seems to think it's a zero sum distortion pastime.

Call your portion of the hobby what you will, stop telling everybody else what to do.

mrkaic's picture

...stop defending myself against audiophile propaganda that threatens to derail progress toward faithful reproduction of recorded music.

Let me ask you the following. Should we watch paintings through colored glasses if we feel that the original is "flawed to begin with"? Should we download photos of paintings and apply sepia or other effects because we don't want to settle for "faithful reproduction of crap? Should we change works of art to "create the illusion of live people"? Because that is precisely what audiophiles do with distorting gear -- they alter the spectrum of the original signal, because they like the "improvements".

Audiophiles have every right to change music to their tastes, but they should confess that by doing so, they strive for LOW FIDELITY. Ideally, our audio hobby should be split into two camps -- high fidelity (scientific, objective) and low fidelity (artisanal, subjective), with low and high fidelity equipment clearly labeled as such. I think that this is a prerequisite to start the healing process.

Anton's picture

Do you like jazz?

Have you checked out "Masterpieces by Ellington?"

Recorded in 1950 and will knock your socks off.

How about "Ella and Louis" by Louis Armstrong and Ella Fitzgerald?

Recorded in 1956, and eerie in its realism. Truly 'in the room.' "Moonlight in Vermont" will give you goose flesh!

Do you think we've made significant 'progress' in recording since then?

I am dubious.

They used tubes, tweaked sound and mic placement by ear, etc...how much "progress toward faithful reproduction of recorded music" am I holding you back from because I like to use my ears instead of gauges?

Don't get me wrong, measurement is great and can give someone a rough idea about matching gear, but it ain't the be all end all objectivists claim it to be.

dalethorn's picture

If it sounds too bright, turn down the treble. Maybe to you that's not high fidelity. Your problem, nobody else's.

Archimago's picture

@Anton,
Hang on a second before you get too angry - for what I'm not sure.

Even Nelson Pass said in this article:
"There are objectivists still working to improve the measured performance on the assumption that it will sound better—not a bad assumption, really."

So based on this, what's wrong with asking for an example of "measures good, sounds not so good"? I notice you don't bother answering the central question and skirt around your "faith" that this is presumably true and that you feel the signal itself is somehow "flawed" so the reproduction can somehow be of whatever type, so long as it *sounds good*!? I believe this is satisfaction of euphonophilia, not pursuit of high fidelity.

You are free to hold these views of course... No problem, but why do you inflame objectivists as "proselytizing evangelicals"? Yes, there are facts. Things like:
- How much power is the amp capable of producing?
- How precise is the stereo channel balance / monoblock pair?
- How much noise rides along?
- How much distortion gets added to the signal not there in the actual recording bought?

Certainly Stereophile appreciates these facts, otherwise they would have no need to publish measurements.

I trust that engineers like Mr. Pass have an appreciation for the importance of measurables - he has a workbench of scopes, meters, signal generators, etc... Great that artistry is merged with engineering. But let's get the engineering right.

So, back to the main question:
In your opinion Anton, what amp do you think measures well but sound comparatively poor?

Anton's picture

Not evading this question: "In your opinion Anton, what amp do you think measures well but sound comparatively poor?"

I don't actually spend time doing that.

I will look at things that, on a large scale, may matter. Things like not trying to use a 2A3 SET flea watt tube amp to drive electrostatic speakers, but do I really care if an amp is 0.0001% vs. 0.000001% THD?

Nope.

So, other than gross mismatches, I audition with my ears and either like a match, or not.

I have noting against measurements, and I enjoy JA's part of the reviews I read. If an amp blows up while he's testing it, I take that into account. If the channels don't match, etc. All good stuff, but that all takes a back seat once I want to plug an amp into my system.

I buy via audition.

Perhaps a fun example: I tried out a Crown amp about 5 years ago. Pardon me for not remembering the model number. I went to their site just now and they have so many 'series' I forget the one I tried. I looked at the numbers and even some reviews, and all looked well, so I tried them. I mated them with a pair of Apogee Studio Grand speakers. They sounded dry, lacking in detail, unimpressive, and didn't keep them in the system.

So, they 'measured' fine, but I didn't like them.

Am I wrong?

I tossed in a pair of Adcom GFA 585's, they sounded much better.

Am I wrong again?

I am honestly not evading your question, I simply don't ride through the audio landscape looking at measurements, buying, and declaring victory.

It would be nice if I could buy without listening, as any good objectivist can do. The hobby would be so easy!

_

I also have an SMSL SA-98E 2 (160 watts!) amplifier I got on Amazon for 90 bucks (usually 114, I saved!)

I feed it from an Oppo UDP 205 and it drives a pair of Infinity Intermezzo 2.6 speakers (with those cement lanscape blocks wrapped in fabric as stands.)

It sounds delicious.

Should I not like it because I don't know how it actually measures?

Do I know it's true RMS power range? It's THD?

None of that. I tried it out and I like it.

Am I less of an audiophile than someone who looks at its specs and draws some sort of conclusion about how it must sound?

For me, the hobby is about listening, and the numbers can be helpful, but aren't the final arbiter.

I mean none of this with anger, and would happily pour you some fine wine that measures the same as lousy wine if you were in my area!

OK, now, how did you shop for your gear?

mrkaic's picture

Anton, you say "Do I know it's true RMS power range? It's THD?"

Well, I measure all my gear in my "lab". I can give you some pointers as to how to do the same with your stuff. You will never look at audio the same way and you will love it.

Anton's picture

I don't really care to buy a lab, I will spend the money on gear I choose...by listening!

I wish we had a 'cheers' emoji, I mean this all in good fun.

Glotz's picture

Few have the grasp of this hobby as you do.

Kudos to you being there every day!

Keep on keepin on.

tonykaz's picture

I've been to 'Live' Music that sounded like a hi-fi system,

Does that count ?

Tony in Michigan

mrkaic's picture

If you are, you are my hero! Keep up the great work -- your blog slices like a hot knife through the objectionable opinions of subjectivists. :))

P.S. Now that was a Freudian slip wrote objectivists instead of subjectivists. :))

Archimago's picture

For the most part, the knife doesn't have to be very hot...

The butter's rather soft to begin with :-).

Glotz's picture

Nelson says it best:

"The discrepancies are interesting because they point to either things that have not been measured—more likely, misinterpreted—or aspects of perception and taste that don't correlate to measured flaws. Or both."

You forgot the rest of the statement, trying to 'de-contextualize' a bit...

The measurements in one's other components (and their gain stages) add another multitude of permutations that affect the sound (and the resultant math).

“So the permutations available for a single stage (in this case, output stage) start at about 10,000 for a single-device, single-ended circuit. This sort of number becomes squared for a two-stage amplifier, and cubed for three-stage amplifier, and so here we are at maybe a trillion possibilities. And we still haven't decided which stages are biased by how much (a continuum of values), or how much each device is allowed to contribute to gain and by what technique. And so on.”

Food for thought. Measuring an entire system (digital and analog) creates trillions more possible outcomes, sonically and mathematically. So what is 'good' sound again?

Archimago's picture

Yes, of course there are multitude of potential permutations and outcomes. But you make it sound as if the permutations can be so severe and differences so extreme that it's almost unrecognizable. If we start with objectively high fidelity products through the chain - say a bitperfect computer --> accurate DAC --> high fidelity pre-amp/amps --> good speakers with reasonable impedance characteristics, time-domain characteristics and flat frequency response; all tied together with decent cables - is that going to sound *that* different between different brands?

Compare the signal chain above with the effects from speaker positioning, noise floor and room characteristics. I would bet the sound would be much more affected by the physical positioning and room characteristics than the gear itself.

Nobody said we can't then also measure the whole system in the room from the listening position and come to terms with the sound as well...

This is of course not to say "everything sounds the same"; rather it's I believe a reasonable acknowledgement that when it comes to the final sound, some differences are more essential than others. Good quality amplifiers being in the mix somewhere but IMO much less of an issue these days than speakers and rooms.

Anton's picture

Questions to answer your questions:

1) Do painters claim to be creating the most physically accurate version of what they are portraying? Do they claim to offer the lowest distortion of the original optics?

No.

2) Do you claim that artists trade in 'lower fidelity' reproduction of what they actually saw?

A painting is already an interpretation - as is a recording. Neither a painting nor a recording is a 'high fidelity' event.

So, I am fine with looking at a painting or listening to a Nelson Pass amp he is experimenting with and enjoying both.

3) As to downloading a photo of a painting: Hell, yeah, change it to your taste. A downloaded photo of a painting is pure crap. There is no 'high fidelity' to it in any way. You are asking for faithfulness to crap. Have at it.

Have you ever been fooled by a downloaded photo of a painting and thought it was the actual painting? If so, LOL!

The photo of a painting is your reference for what the painting looked like - nice. That photo of a painting is the same as an audio recording, a flawed attempt to portray something. Feel free to tone it, saturate it, texture it, whatever you like that gives you more of the feel of the original.

You may, as an "accuracy" acolyte, insist that the photo of the painting is the most true to the experience of the painting. I would laugh and wonder what kind of crap you put on your walls.

_

Audiophiles who want a 'closer to live' sound, to you, are lowering their sights and striving for 'low fidelity.'

Sir, the source is low fidelity, what do we owe it?

We are hobbyists, not keepers of a sacred texts.
I say we aspire to create the illusion of live music, you think we must be servants of a recording. Tyranny!

There is no 'healing process' required, no confessions to be coerced, we all follow the same rules of physics, so what is this stick up your sigmoid about something 'objective?'

Maybe you should go read a good symphony.

;-D

prof's picture

A painting is already an interpretation - as is a recording. Neither a painting nor a recording is a 'high fidelity' event.

Who is the painter in your analogy?

a) The musician?
b) The recording engineer?
c) Or the amplifier designer?

I would say, "some combination of (a) and (b)."

To follow your analogy, (c) would be like the gallery owner or museum curator who put up colored lights or a disco ball to make the painting "look better."

No thank you. I'll trust the artistic judgements of (a) and (b).

Anton's picture

Have you met anybody who has claimed that the musician or recording chain engineers have claimed that their recording is the true event?

If not, all you have been buying is flawed representations of an event.

To follow your analogy, should this painting you mention be hung in the dark so as to avoid all subjective 'colorations?'

Is it the artist's or engineer's prerogative to tell you how to best present the painting? How high to hang it, how to light it?

Who determines the best objective method for placing and lighting the art?

If your way differs from mine, you suddenly wish to make some empty claim about your way being closest to the objective truth?

No, again.

Perhaps you'd say the way the painting was lit in the gallery is the objective truth?

LOL!

It's all subjective.

_

Not to say that an amplifier factory should be stocked with a thousand monkeys at a thousand work stations and we wait to see what comes out. Design and measurement is fine, up to the final decision by the consumer about what he or she wants.

Questions: When you go to another objectivist's house to listen to his hi fi, does it all sound the same? If not, which one of you is correct? Have you gone to listen to gear at a subjectivist's house? How do those systems hold up?

I find differences from system to system, be it objectivists or subjectivists. WE are all wrong and alright.

prof's picture

Who determines the best objective method for placing and lighting the art?

That question has a fairly simple agreed-upon answer. The ideal spectral composition of the illumination is that of natural daylight.

In the case of an amplifier, the answer is even easier.

An "ideal" amplifier takes an input wave-form with peaks at 1 Volt, and outputs an identical wave-form with the amplitude (peak voltage) boosted to 25 Volts (or whatever, depending, on the power-rating of the amplifier). Hence the word "amplifier."

While no one achieves the ideal in the real world, high quality amplifiers come strikingly close (as does the lighting in modern museums).

I'm genuinely shocked that anyone would actively prefer colored lights and a disco ball.

Anton's picture

Natural daylight - how bright? From which angle or angles? Desert light at what time of day for a Georgia O'Keeffe painted in Santa Fe? The light of Provence for a wheat field, but the wane sunlight of Amsterdam for images of gleaners?

What kind of bulbs?

Filter out UvA and UvB?

We are talking about nuances, not somebody wanting strobes and mirrorballs.

Same goes for some audiophiles' amp preferences.

Someone may prefer the hard light of noon in Dodge City, another may prefer 5 pm in Tahiti. All natural light, just one person's preference. Does one need to call the other a "low fidelity" light?

prof's picture

We are talking about nuances, not somebody wanting strobes and mirrorballs.

Nuances?

So it's not "all subjective". We're actually talking about subtle variations about some baseline. But what baseline?

I gave my answer for what that baseline should be for an audio amplifier: take the input signal and boost its amplitude without any other changes*. Do we, at least, agree on that much?

* Again, not perfectly achievable in the real world, but high-quality amplifiers can come damned close.

ok's picture

In fact most modern solid state amplifiers above 500$ measure quite well – let alone digital sources where usual measurements almost have no meaning – regardless the fact that even the most decimal electronic distortion sooner or later must face the speaker’s inevitable bottleneck. Should we assume then that blind luck combined with budget concerns is the proper way of choosing audio gear? Well, truth be told, I have tried it more than once and man – it works..

Herb Reichert's picture

Like surf music?

ok's picture

[..]this phenomenon relates to what people think real music sounds like. What are their opportunities for listening to real music? We return to those espousing the closest approach to the original sound, often identified as the sound of live, unamplified music in a real space. But what original sound? If you are going to listen exclusively to large-scale orchestral music, there are very few places to properly experience it. Small-scale orchestral, chamber orchestras, you still have very limited opportunity. I’d say the vast majority of high-performance enthusiasts do not get to listen to live, unamplified performances on a regular basis. Even a lot of orchestral performance is amplified or augmented these days. Everything else is almost always amplified. So what’s the reference point? What are they looking for? Beyond the live event, most music is created in the studio.. When going out to record a performance, what [the recording engineer] is capturing and how does he capture it? When a soloist plays and you are there watching, your brain interprets and focuses on the solo. If you just monitor the flat capture with a pair of microphones, the soloist gets lost in comparison to what you remember hearing when you were there. Because of the type of microphones, and their placement to capture the essence of the performance, it is not a true, holographic representation being captured, but rather the creation of something approximating the “live” perception had you been there. There is no reality. So what is it we listen to? Someone has an idea of what they want to hear from music. How can we tell them they are less right, when there is no clear relationship between what the music was in the original performance and what we can hear from our systems?

mrkaic's picture

August, many thanks for your succinct summary. You have done in one sentence what I tried to do in one paragraph.

Archimago's picture

What's with all this discussion of painting, painters, etc.??? That's not even at the level of analogy when arguing about gear and amplifiers.

Yes, the recordings we buy are already "pictures of the painting". We as consumers have no real power as to how the artist sang, played the instrument, what gear was used to record, how it was mixed, or the way the mastering engineer added EQ or set the average level. The gear we own and arguments we have amounts more to "What computer monitor or TV screen shows that picture of the painting in the best possible way?"

Depending on the person, here are some options:

- Some just want a nice looking monitor sitting on the wall flush, thin, and unobtrusive (looks beautiful, 'lifestlye' product, furniture).

- Some audio lovers focus on the image and fit it to their esthetic impression of what the picture *should* look like - they don't mind if there's a slight deviance from pure grey scale, or if the contrast ratios are exactly to spec - if it looks good to them, then it's all in the "eye of the beholder". (subjectivist)

- Some want to make sure the monitor is well calibrated, the color gamut is full, contrast ratios can express the various "stops" captured by the camera / recording (eg. like how a modern 4K HDR can express brightness more realistically, or hi-res DACs capable of lower noise floors), white point at the correct Kelvin... (objectivist)

I trust we all consider elements of the 3 when we buy products - including consideration of our needs, WAF, budget, how it looks, etc.

However, IMO, it would be ridiculous to not see the "objectivist" perspective as having a clear ability to achieve a level of performance and understanding of the underlying engineering principles of what makes a "good" engineered product. Being an "extreme" or "pure" subjectivist who refuses to acknowledge the importance of measurements makes no sense!

mrkaic's picture

Anton, this exchange has been fun, I thank you for a spirited debate. However I disagree with you for the following reasons.

1) A painting is an original work of art, not necessarily an interpretation of anything as you say: "A painting is already an interpretation - as is a recording. Neither a painting nor a recording is a 'high fidelity' event."

What does a Magritte or a Mondrian interpret? Maybe an abstract idea, but nothing that necessarily exist in real life and needs to be "recorded" with fidelity. Hence I find your writing about the "fidelity" of paintings to be misguided -- the fidelity of paintings is an undefined term.

A recording is a work of art in its own right as well, something that uses music as an ingredient, but exists as an independent genre. They give Grammy's for sound engineering for a reason. If I want to listen to live music, I go to the symphony. If I want to listen to recordings, I use accurate audio equipment.

2) You like your gear to change recorded signals to "improve" them. This is equivalent to using optical filters to "improve" paintings, which is exactly what I wrote. You use filters to "improve" works of art. Do you like to "improve" paintings by using colored glasses when you are in a gallery?

3) You also said that "audiophiles" like to make recordings more like live music -- your words, not mine. Fine, but how do they know that they are actually making the sound that comes from their gear more like live music? They only imagine that. I say imagine, because they really don't know if they are matching live music, do they? They choose low-fi gear to target the IDEA of live music that exists in their heads. How can they know that the sounds that are coming from their speakers match those coming from an orchestra in a concert hall? They don't, they just imagine that there is a match. And that is the ultimate irony -- one would need to measure both his system and the orchestra in a concert hall and then compare both scientifically to actually know if he is recreating live music. :))

Anton's picture

You said: "You like your gear to change recorded signals to "improve" them. This is equivalent to using optical filters to "improve" paintings, which is exactly what I wrote. You use filters to "improve" works of art. Do you like to "improve" paintings by using colored glasses when you are in a gallery?"

I said that recordings are flawed and some audiophiles find second order distortion to add a pleasing effect.

We are all trying to create the illusion of live sound. So, if those audiophiles find that the second order distortion seems to create a more pleasing illusion, then, for them, that is higher fidelity.

I'm not a second order groupie, but don't care if other audiophiles prefer it.

When I hear that effect, it does add some bit of 'excitement,' but I find my appreciation of it fades because it is happening to all the recordings they play and the illusion is somewhat quickly lost, for me. The same effect, over and over, is what I don't like about it.

You said: "You also said that "audiophiles" like to make recordings more like live music -- your words, not mine. Fine, but how do they know that they are actually making the sound that comes from their gear more like live music?"

They know because it reminds them more of what they hear when they listen to live music. D'uh. They prefer that sound to the sound of other gear.

Easy, happy!

"They only imagine that. I say imagine, because they really don't know if they are matching live music, do they?"

Well, how do you know? The waveform in the live event is certainly dissimilar to your listening room, so what we are all doing is some brain filtering to help our systems along. Objectivists and subjectivists are all simply celebrating degrees of failure when it comes to emulating live music.

You said: "They choose low-fi gear to target the IDEA of live music that exists in their heads. How can they know that the sounds that are coming from their speakers match those coming from an orchestra in a concert hall?"

Actually, the same way you know. You don't sit there with a mic and screen and have any way to know what sitting at the live show sounded like. You are turning your measurement fetish into a faux virtue. We all listen and compare based on our experience of live music. You like to call some listeners names, they like to point at you and your calibration microphone and laugh. None of us are getting a live equivalent.

You said: "They don't, they just imagine that there is a match. And that is the ultimate irony -- one would need to measure both his system and the orchestra in a concert hall and then compare both scientifically to actually know if he is recreating live music." :))

Are you doing that?

How do you know anything sense based? By mentally comparing it to past experience. Food, scent, touch/texture, taste, sound....we do it all with our wonderful neurologic sense comparator.

Like I asked upstream, have you every been fooled by a hi fi system into thinking you are attending a live performance?

I have not.

How did I know it wasn't live? because I can recall what live sounds like.

Seriously, do you run into a system for the first time and say to yourself, "Well, unless I can go and get measurements of the original sound and measurements of this sound, for all I know this is actually a trumpet making noise in this room!"

No, you don't do that. You use your ears, same as me.

So, post any appeal to numbers and machines that you desire...I know you use you ears to listen.

Really, relax and listen.

ok's picture

I think that the John Atkinson 2011 AES lecture “Where did the negative frequencies go?” answers the main questions posed here and raises even more new interesting ones for that matter.
Audio measurements are much like medical measurements in the following sense: their purpose is to locate malfunctions, but they cannot guarantee absolute health or champion performance – the main reason for this being the fact that they never are all the possible or adequate measurements. More often than not prodigious athletic or health scores raise suspicions of heavy medication (aka tons of negative feedback or DSP correction in audio matters) with its own side effects and unforeseen consequences. Measurements are most valuable to the doctor or the engineer in order to correct certain deficiencies – but more of psychological value to the patient or the listener who just wants to know if one is allowed to keep doing what one always did.
By the way, has anyone ever seen two identical sets of measurements of the same specimen from independent third party laboratories? Do these inescapable fluctuations render measurements “subjective” or fundamentally unreliable the same way “objectivists” claim about listening tests? Do really people hear radically different things in reproduced music or is it just personal interpretation that makes most of the difference?

Anton's picture

Your comments are worthy of six bottles of wine to work through!

ok's picture

One final word: I listen to music because I like music; if some certain configuration makes me like it even more so, well – that’s all right; if the whole damn thing makes me hate it all the more – it’s all wrong. I don’t give a dime what the poet or scribe thinks of it as long as it works for me all the way through; I can fully understand that certain people tend to prefer natural beauty over artificial paint – but measurement geeks are not that kind of people.

davidespinosa's picture

Plenty of evidence that science is a work in progress:
https://www.quantamagazine.org

Too bad US science funding is so low.
Might be easier to find work as a musician...

Glotz's picture

"There was a consistent subjective observation that there was a difference not only with the level of second harmonic, but phase also. Negative-phase second harmonic tends to expand the perception of front-to-back space in the soundstage, separating instruments a bit. Positive phase does the opposite, putting things subjectively closer and "in your face." I have heard this sort of comment from people who were not in a position to have expectation bias, so I treat it seriously.

Of course, there was also such a thing as too much second harmonic. It is a trick best done in small doses."

Herein lies the essence of subjective perception of what sounds 'good'. It's controlled by the designer to subjective demands of a segment of amp buyers by engineering that includes or omits distortion for sound sake (because you're buying amp to listen through, not Audio Precision responses).

Even on a 'near-perfect' measuring amp, there is the ability to dial in 'too' much 2nd-order distortion (sustain) and too much negative feedback in the loop (balance between image solidity / transparency and depth /width), or at least make the balance unlikable for some segment of listeners.

Again, we are always left with 'what is correct?' even when measurements tell you that solid-state is better than tubes, and digital is better than analog, when each can be manipulated to sound 'great'.

It may take 10x the amount of money to get to similar engineering levels with analog vs. digital or tube vs. solid-state / digital, but I firmly believe great gear defies measurement-logic frequently, and the most-practiced ears can hear it!

Zarathustra's picture

"Toward that end, I like simple circuits, partly because well-designed, simple amplifiers tend to sound better, and also because they bring the part's personality into sharper relief.

This relates nicely to tubes, in that the economics of tube circuits enforces a discipline of simplicity, where it is not convenient to achieve quality by throwing lots [of] parts and feedback at the problem. You will not see 50 tubes and 80dB of negative feedback under the hood of any tube amplifier.

However, most of the best approaches to tube design are well mapped already. Not so much with solid-state, where the art of simple has been somewhat neglected and where there is a vast array [of] new and interesting parts. That's why I choose solid-state."

Sow what Nelson Pass says here de facto that he has chosen to design amplifiers with a transistor topology not because he thinks he can make the best sounding amplifiers with transistors, but because they are much more a challenge for him. So he's not interested in bringing the best sounding amplfiers to the market in absolute terms but trying to make the best solidstate amps by use of simple designs like tube gear has with devices that mimic tube behaviour.
Wouldn't it be a rational behaviour for audiophiles to spent their money on the original the tube-amplifier with their "mapped" and proven trackrecord than financing a neverending quest for the best solidstate copycat?

Just a thought....

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