Conclusion -
You've covered the question. Everyone should know their number or narrow range for what they can detect.
If a given amp goes above your personal threshold for Any reason (eg. too low Z load for given spl), you can say it has changed from its neutral character. You can say it no longer sounds neutral. Some will go into describing what that distortion character has added to the sound. However, if your load isnt as low or spl as high or your threshold isnt the same, you have the makings of a disagreement about that amplifier's neutrality.
Thats how it plays out from what I read on this and similar forums.
IMO.
THx-RNMarsh
You've covered the question. Everyone should know their number or narrow range for what they can detect.
If a given amp goes above your personal threshold for Any reason (eg. too low Z load for given spl), you can say it has changed from its neutral character. You can say it no longer sounds neutral. Some will go into describing what that distortion character has added to the sound. However, if your load isnt as low or spl as high or your threshold isnt the same, you have the makings of a disagreement about that amplifier's neutrality.
Thats how it plays out from what I read on this and similar forums.
IMO.
THx-RNMarsh
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Very fortunately, that is not the case ... the illusion of realism is very achievable, and has been for a long time - the failure by the industry is not realising the tremendous importance of the subtle, almost throw away factors in the overall engineering of any one particular system. If these factors are ignored or downgraded in significance then failure to achieve satisfying realism will be the result, every time.
Human hearing wants to make complete sense of what it's picking up, but if its job is made too hard then it just gives up - you have 'crap' sound. But give it a helping hand and it will reward you, the listener, with a very rich and involving experience - the real trick is understanding what the ear/brain hates having to continuously process and filter out as being irrelevant to the listening, and what it can quite happily accommodate on an ongoing basis without fatigue.
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My best ever Aussie friend said that it "was made for me", I never quite figured that out. Never could get through the whole thing.
Any suggestion for standards? Or everyone makes up their own self fulfilling tests.
Since this would be a measurement vs listening detection threshold, the test equipment currently available would be used.... and the tests they can perform. If it is known that certain tests we can do are more sensitive than another use that. Certainly, there are tests which could be done which are not at all very sensitive.... those should not be used. Maybe more than one test would be needed.... a threshold test for this and a threshold for that.
Once a few thresholds are established, we can decide under what conditions can amplifiers exceed them. And then, be 1/10 of that to assure the whole system chain will not break thru the detection 'threshold'.
THx-RNMarsh
No such assumption is made... of course a few threshold tests does not make a 3-D coverage of the whole detectable range of things.
Many here say one cannot hear this or that while they have no idea of their own detection thresholds of the many factors.
It isnt an easy task to do it all well. And, to identify new distortions or the next dominant distortion and their thresholds or how to minimize them to undetectability.
At this point in time, the total affect of the record/replay system is still detectable; When you compare D-to-D or Master HD files you know distortion in the chain is still an issue to be solved.
The good news is that we are now a lot closer to perfection that ever before.
THx-RNMarsh
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Richard, although I agree with your basic position my greatest problem does not lie there.
I went to the opera last night and I tell you my system doesn't produce that aural experience but I don't think the problem for me is my system's distortion. ( I live in a high noise environment so there's no point in going much below .1%, I think).
But if I want a better sound stage and envelopment and the subjectively big sound and detail I heard last night, without generating outrageous SPLs at my listening position, then I have to have more point sources. If I were in a quieter environment then my concern would be closer to yours.
Hearing some acoustical music in Disney Hall in good seats is revelatory. Strauss, Also Sprach Zarathustra, which I knew well, was practically a new piece.
And although SPLs were sometimes fairly high, that was hardly enough to explain the qualitative differences to home reproduction.
I think there is FAR too much nonsense around distortion. .01 or lower at close to rated power at 20 KHz is fine. The harmonic content is important. There is enough on this subject from the luminaries on this thread. I see amplifier designs on the forum that are nothing less than monstrosities in pursuit of single digit or sub pm distortion levels. Dynamic range, low noise, flat response are equally as important as is the ability to drive a real world load. Much more of the sound of a system has to do with speakers and their interaction with the room.
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I certainly feel the same.... in my home it does not sound like live instruments being played when I use the Hi-Fi system. I already discussed this and my suggestion was to resurrect the sound-field microphone system.... at one point we almost started to make a new one. But it is being revived I've seen, thank Godness.
BUT, this isnt a speaker forum... John makes/designs amps and preamps. So, that is what I am sticking to. I have stated that I use very low distortion spkers and headphones didnt I? They are far better than run of the mill types or even many Hi-End models. Any of you can have same, if you want. Then you will hear everything more clearly and your thresholds lowered.
As for going far below .01% --- every stage in the record/playback system needs to be low enough to not accumulate to a >.01 level that is detectable..... unfortunately that isnt the case. One or two pieces at home?-- like a preamp and power amp... OK .01% is your number. LP doesnt make the list [ yes, it sounds nice ].
THx-RNMarsh
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Harmonic content is important below .01%? Have you tested that yourself?
That pursuit of <.001% THD is great work. It is fun, educational, and inventive. Even as a hobby. Someday it might be the norm in studio gear.
I am not saying that is needed for your home amp. Back when I had young ears but only Mid-Fi, I lost the difference at .05%. Maybe someone else (a woman) could do better today. So be 5-10 times better so you are sure NoOne can detect the amps presence due to distortion threshold exceeded.
I think the point is made. John listens, his friends listen, and he tries to get his designs below their thresholds to detect.
For myself, I also try just as hard to get the highest quality, lowest distortion sources. And, the highest quality, lowest distortion speakers/headphones.
THx-RNMarsh
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Richard , 10ppm is a standard goal for a power amp , but something
like a line stage , or other intermediate audio stage , why not sub ppm.
I just found a "Lehmann" headphone amp buffer. (below).
Very widely cloned by the asians , they just slap a NE5532 behind
the diamond and most audiophiles give above average reviews.
My LT1028 model just "floored me" !!
(below 2). The buffer
and it's feedback just "dropped the bottom out" of the IC's THD .
Worst I could get was .2ppm 20k (33R load).
I have a better discreet buffer than the Chinese clones (and a better IC) ,
but what a good price/simplicity to performance ratio !!
Any part of your audio chain where you can just eliminate distortion is
an improvement.
OS
like a line stage , or other intermediate audio stage , why not sub ppm.
I just found a "Lehmann" headphone amp buffer. (below).
Very widely cloned by the asians , they just slap a NE5532 behind
the diamond and most audiophiles give above average reviews.
My LT1028 model just "floored me" !!
(below 2). The bufferand it's feedback just "dropped the bottom out" of the IC's THD .
Worst I could get was .2ppm 20k (33R load).
I have a better discreet buffer than the Chinese clones (and a better IC) ,
but what a good price/simplicity to performance ratio !!
Any part of your audio chain where you can just eliminate distortion is
an improvement.
OS
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What I've noted in the hall is that since I'm easily 60 feet from the stage, what SPLs I'm hearing can not be even close to an acoustic watt even when the orchestra and singers are each producing an acoustic watt measured at close quarters. What makes things sound loud is the reflected sounds which are delayed enough that they are subjectively point sources and each addition of a point source gives a subjective increase in sound.
Also, since HF is absorbed by air, and the reflections travel a greater distance than direct sound our auralization of space is engaged. Further, during quiet passages the direct sound of mids and highs is relatively louder, subjectively, than during loud passages because more of the reflected sound is masked or composed of fewer audible reflections and this is an attention grabber - experienced perhaps as intensity or intimacy.
Sometimes the these aspects of live performances are recorded but can be lost due to deficiencies of transducers or electronics or listening environment; they are after all recorded necessarily at low levels. Smart audio engineers have always emphasized these phenomenae due to loss of visual cues but even then these compensations subjectively often are not satisfactory because their sound comes from the front.
I think the bad characteristics of noisy or small rooms can be masked by the better qualities of adequate spaces using more point sources. One great advantage of this is that it means the front speakers don't have to be as loud.
Even ordinary stereo listening can be improved with extra point sources adequately delayed and rolled off.
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