Toob sound?

Well, I have no doubt whatsoever that 0.5% 2nd harmonic sounds different from 0.5% 3rd. I don't see that as being debatable. Those sorts of test have been done. Its imd that thats at issue as well. A 1k and 1.4k generating a new 400hz at 0.5%,

You are actully way, way, out there on this.

See below before opening one mouth:-)

I can. Its trivially obvious. 2nd harmonic is twice the fundamental, so a g harmonic sounds likes root g. 3rd harmonic is a d on top of the g. You bet your booty you can hear that extra d if its large enough.

I am. There is plenty of evidence for that. Load and loads.

Download the files and listen mate. Hint, a 0.1% thd way worse then

You need to become a bit more aware, mate.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

Correct.

Curiously, there is a wealth of evidence that suggests you are delusional on this matter.

Note the mp3 discussion.

John Atkinson (Stereophile), who is a die hard golden ears boy claims exactly what you claim, but admits to doing numerous controlled tests all with a null result, and simply claims that such tests must be false because he "knows" that there is a difference in non controlled tests.

So, I am with you on the distortion issue,

No thanks. 30Hz square wave modulation is what they use for the Daleks.

Not today.

No chance. Times have moved on. Producing an amplifier with say, 0.001% thd/imd at 20Khz, is straightforward

There is simply way, way more to producing a successful selling product then specs. To wit, Windows.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

Assuming there is a threshold of detection, I don't really care if it is

If you can hear the difference between two different amps respectively rated at "0.5% 2nd" and "0.5% third" in actual music program material, then good for you. If you can only detect it with pure tone input test signals, it doesn't count. Like I said, I am not aware of I am not aware of any scientific study that conclusively shows that humans can reliably detect different characteristic distortions under 0.5 to 1.0%. Maybe it exists, but where is it?

Oh boy, you really got me.

I like your "IF." "[I]f its large enough." Of course, if it is large enough. No one is arguing that. You should have know from *context* I wasn't talking about some guitar amp deliberately driven to high distortion levels. After all, aren't you the guy who wrote "Producing an amplifier with say, 0.001% thd/imd at 20Khz, is straightforward?"

When I say I can't claim it, I'm talking about hi-fi amps, with the characteristically low distortions available. Obviously I can hear the difference at some higher level, but I don't know what my own threshold is (don't really care). Whether it is "absolutely" 1.0% or 0.1% or

You can argue some one-size-fits-all figure-of-merit and that 0.5% is too high, but I think that misses the main point: Humans likely have a threshold of audibility and hi-fi amps are available below the theshold of humans.

Have out with it. Please constrain your "loads" to hi-fi amplification.

Nice. The audio industry is apparently 20 years behind the communications and control industries. That's impressive. I am not universally fond of simplistic THD or intermod (THD, as used, is simply a special case of intermod) representations either. That's why I wrote: "for as good or poor as the gross THD spec is." But it is simple and most people know about it, and I'd rather keep it simple if it suffices for the context. For weakly non-linear systems (apparently loudspeakers are an example) using the terms of the more complete Volterra-Wiener polynomial model would be superior.

I don't know what is up with Geddes, in his .ppt file he couldn't even get the title of Schetzen's book (the "bible" of non-linear systems studies) correct. Has he read it?

_The Volterra and Wiener Theories of Nonlinear Systems_, by Martin Schetzen ISBN: 0471044555

I was looking for papers and references on non-linear system theory in the context of predistortion for RF amplifiers some years back. Schetzen's text was almost universally referenced in all the papers I found. Schetzen studied under Wiener at MIT (it was Wiener who first recognized the applications of Volterra's equations for non-linear systems). Wiener is also the so-called father of cybernetics. It took me about 4 years to find and grab a used Schetzen text off the market (at a price commensurate with supply). There are some relevent IEEE papers by Schetzen too.

In any case, for loudspeakers, Gedlee talks about using the memoryless polynomial model of Volterra rather than the complete Volterra model which includes memory. That's nice, because not including memory effects makes it easy. But my concerns here are mostly about amps. I think speakers might be the most difficult problem in hi-fi.

You could use your 0.001% amp and then sum with non-linear blocks providing 2nd *xor* 3rd order distortion at 0.5% at rated power (before hard clipping), listen to actual musical program material in a double-blind test, and prove your claim of being able to hear 0.5% characteristic difference with music program material. I almost assume you've done this, since it is your apparent claim.

Incidentally, can you think of a problem when applying the Volterra-Wiener polynomial model to something like a typical audio power amp (basically a powerful op-amp). I can. Maybe that gross THD/IMD spec isn't all that bad. Why?

Oh, for sure. But what is your excuse? You pointed me to a reference, which itself referenced something (incorrectly) I had already mentioned. What is up with that?

nonlinear googlization:

From what I've heard, I agree about speakers. That's where "the fruit is" in my opinion. That's why I stuck with amplifiers, which are at commonly available with at least a couple of orders of magnitude better performance when it comes to distortion.

If your speakers are an order of magnitude worse, which they probably are, then you would be spending "better money" on the speakers. Amps with < 0.01% distortion are commonly available for reasonable cost.

It is not clear to me that people can hear (differentiate) at the 0.1% for music program material.

Paraphrasing what I said: "if I can't hear the difference, then I don't care about the particular characteristics of either (certeris paribus)." I'm explicitly saying "can't hear it."

You're simply calling out the defects (*why* it is a crappy way of compensating). I happen to agree it is a crappy crude way, but compensation it is. It compensates for one thing and brings baggage with it.

I'm talking specifically about the information that provides meaningful data on what people can and cannot hear in the threshold neighborhood. What I'm saying is that it is cheaper to simply build a 0.001% amp for someone, than to figure out if that person's threshold is 1%, 0.1% or

I've designed in environments where it mattered if a capactitor cost

Think cost. If the benefits are diminishing, and purchase choices are made at the margin, then cost counts and "necessary" is subjective, if for no other reason than the information costs. People can make whatever subjective choices they want -- it is nothing to me. However, margins in much of audio industry are thin and competition is high. In that near perfect competition environment, the consumer is god. In the aggregate, consumers are saying it isn't that important, even if they

I think I was clear. I said I am not aware of evidence that people can reliably detect the low levels of distortion that are commonly available in todays hi-fi amps.

I am aware of no current need for people to have cars that go 1000 mph. I don't think Chevy is either. So they don't make 1000mph cars.

I never said "low distortion" was not a commercial consideration. Obviously some manufacturers spend more efforts than others on this, depending upon what part of the audio market they focus on. In itself, that says nothing scientific regarding what people can really hear.

The company who does that will likely also find a way around the 2nd Law, so yes, those'll be some rich folks who discover a commercially viable 0% amp.

Well yes, money, or more accurately the resources money buys. That is a general condition of life, and the audio world escapes scarcity no better than any other. Purchase choices of consumers are sending a message regarding how they wish resources to be allocated. Few say $10k power amps to listen to tunes is worth it.

Test it. Put a disguised guitar amp -- with much higher distortion -- on the market, pretending it is a hi-fi amp. You tell me if a hi-fi amp with design goals of low distortion doesn't sell better than the high distortion guitar amp.

As low as distortion as possible for the market/price/cost constraint is the most basic design precept of hi-fi. It is #1. The fact that it is non-zero doesn't change the fact that ignoring consideration of driving down distortion is a no-no. If you ignore that consideration of low distortion as a design goal, you'll get a crappy amp, unless you're really really really really lucky.

Sure, making a living is important. All I would say is that the golden-eared crowd is a niche market. The reasons they purchase what they do is not rationally identifiable, so nonsense hype may be as much a reason for their purchase as anything. Yes, *give them what they want* and note that hype, for example, may be what they want as a value-add to their sound system. Hype has a high gross margin if you don't need too many glossy catalogs and expensive ads. Executives love it.

respectively

material,

test

Since theyre part of real life music, clearly it does count. Solos, theremins, pianos, even sig gens have been used in music before.

And of course if the threshold were 0.55%, it still doesnt follow that it doesnt matter as long as your amp is below .55%. Why? First distortion elsewhere in the chain, 2nd the possibility of partial cancellation of speaker distortion, which if achieved might make an audible improvement. And 3rd the possibiilty of partial compensation by a different type of distortion.

Reliably isnt the question. If its ever detected, it matters in a competitive hifi industry.

NT

This is besides the point of your lack of knowledge on proof that a gross thd spec is insufficient, if the thd/imd is too large, especially for value as large as 0.5%. I do agree, that if the thd/imd is low enough, differences between them cannot be detected.

Well, you should have read the whole post first, because the evidence for this is everywhere, and you seem to be completely oblivious of what the files referenced proved.

Yep.

But that's what I am taking issue with your "not aware...at 0.5% level..etc"

This is blatantly incorrect. You phrased your assertion in such a way as to imply that there was no reasonable doubt that such distortion levels could not be distinguished, when in fact, only those pretty much completely ignorant of the field would imply such a fact.

I don't see that there is a threshold, but there is a smeared limit range, below which distortion is inaudible. It depends on frequency for starters.

I am confining my self to your assertions and implied assertions of facts. Whether its hi-if or not is irrelevant.

Your implied facts are incorrect. It is those facts I am dealing with. Stop trying to weasel out by changing the subject.

But apparently, way ahead of you. It is aware of much of what you aren't.

I use the claim that a *real* amplifier with distortion < 0.01% thd/imd at 20 Kkz, has distortion that is audiable undetectable.

Such an amplifier, invariable has low frequency distortion in the 0.002% range, just because of the mechanics of amplifier design.

I don't claim that this is a maximum lower bound. It *might* be 0.05%.

Note that Spice small signal distortion analysis uses the Volterra model.

What am I missing here? What are you missing here?

I have just pointed you to files with 0.1% thd, and the distortion in them was trully dreadfull. The case is closed.

I haven't read hardly any of this thread.

Kevin Aylward snipped-for-privacy@anasoft.co.uk