Pete, Lock-in amplifiers, wave analysers, and synchronous detection are no secret outside of audio. THD + N plots are completely useless at mV and below levels so to get true THD down to near 0 output these techniques (as well as equivalent FFT methods) are needed to remove the noise in favor of the fundamental signal and its harmonics.
I have seen measurements of Halcro (just to name one of the ppm at full power crowd) amplifiers that were considerably worse than a DHT tube amp at mV output levels. I make no claims at all that this matters.
just so i'm clear on this statement your saying that non linear distortion is only audible after the determined threshold has been exceeded?
so is linear distortion to be thought of in the same way?
sorry for probably stupid questions but something i thought i understood (but apparently don't) is causing me to lose sleep over this and i'd like to sort it out.
thanks for your patience!
I never mentioned "threshold" and it is not something that is very well defined, nor anything that we tested for.
No, linear distortion is nothing like this, it is significant at any sound level.
It is not uncommon for people to lack an understanding of nonlinear distortion, that's why I did so much testing on it. I once thought it highly significant, except for specific circumstances, I don't anymore.
what does this mean then?
this is where i take it your stating a threshold has been crossed and after this non linear distortion is audible,yes or no?
What distortion you get and whether or not there is a threshold, soft or hard, etc. all depends on what's causing it. Use your imagination. If a speaker cone hits the end of it's travel there is probably going to be an abrupt distortion threshold at that point, right? If the magnetic field gets a little more misshapen out towards the end, then maybe distortion gradually gets worse as the voice coil moves farther out. There are so many possibilities of what could happen that one can't make hard and fast rules about thresholds and many other things. It's not like theory dictates what can happen. The physical world dictates what can happen. Theory is to help us understand it and predict it.
Regarding what is audible, there is only research for what most people (maybe 95% of people) can hear under specific test conditions. There is no Guinness Book of World Records category for the human that can detect the smallest possible distortion. If there were, then maybe we could say with absolute certainty what the limit of audibility is based on however the record holder was measured. But, measured another way, or for a different kind of distortion, maybe we still couldn't say exactly.
Regarding what is audible, there is only research for what most people (maybe 95% of people) can hear under specific test conditions. There is no Guinness Book of World Records category for the human that can detect the smallest possible distortion. If there were, then maybe we could say with absolute certainty what the limit of audibility is based on however the record holder was measured. But, measured another way, or for a different kind of distortion, maybe we still couldn't say exactly.
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There can be what we may describe as thresholds for distortion production and also for audibility. But remember, these are fuzzy analog things that we are trying to categorize. Because these things can be somewhat blurry by nature, you can't expect razor edge definitions to be an exact fit.
No. Its where the scale on which we measure and discuss nonlinear distortion has been exceeded. The threshold - if one exists and with what type of signal, could be much lower.
You asked how the Fourier series is transformed by a nonlinearity and I answered you. In order to do that we need to draw a line above which we will not discuss because we have exceeded what the math allows. This level can be picked anywhere, but without stating what it is we cannot scale what is audible and what is not.
To some this is gibberish, others follow I should think.
You are jumping back and forth between the analytical descriptions and the subjective. Unless you recognize this you will always be confused.
I'll go back and look, but I remember you just refused to provide any results. That isn't helpful.
You said that, but didn't say how. I would be a big help to know how you would cheat the Foobar ABX test because it has been suspected in the past that some people were doing just that. I've heard from other sources that it's trivial to cheat it, but have never had anyone provide details on how it would be done. Knowing that would be a great help to the community.
Either loop back the digital output of Foobar going to the sound card and run it into an analysis program on the same computer (I think there may be some add on utilities for this, maybe like this VB-Audio Virtual Apps ), or route the audio output to a spdif device on the foobar computer, then into the spdif input on another computer, and into an analysis program.
In my particular case, I have a desktop and and laptop and can easily go between them with spdif, so no problem getting the digital output from foobar into an analysis program.
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Since I'm a known rude boy, I'll jump in here.
I would say that within the range of domestic "loud but not insane" the horns do run into trouble, and that is audible. Of course you'll be told not to believe what I heard, but there you have it.
Having heard Gedlee speakers playing this loud, or softer - I'd say they were past their maxSPL for clean sound. The woofer does fine, but the CDs start to break up and sound "blatty" or uncontrolled. Whatever the adjective, they quickly reach a point at which they no longer sound good. And IME, that's before 120 dB SPL peaks. Otherwise, they are a good modern implementation of a classic design, a 12" high efficiency woofer mated to a 1" horn and driver. The box is a little undersized for the woofer (Abbeys), but they are meant to be used with subs anyway - so that works.
I would say that within the range of domestic "loud but not insane" the horns do run into trouble, and that is audible. Of course you'll be told not to believe what I heard, but there you have it.
I have no wish to suffer through foobar abx. I see no reason to submit myself to that for the arbitrary satisfaction of Pavel. I can do blind testing my own way using Reaper, something I have been doing for a long time when I need to be sure if something sounds different.
I understand some people will not participate honestly in testing, so foobar ABX is seen as a way to prevent any cheating. Since it can't really do that, I feel even more like not submitting myself to suffering with it.
Anyway, initially I said I would not use foobar ABX as it exists now because it is such a pain. Later I asked Pavel what foobar ABX scores he would accept, but at the same time I warned him that anybody could easily cheat. I don't think he liked me doing that, and he didn't answer. However, I'm not sure he wants to give an answer of what foobar score he would accept, since he has already decided hearing a difference is impossible. Probably no score could satisfy him unless multiple people he trusts could all show differentiation. Even then he would probably suspect an error somewhere.
From this side of the glass that just sounds like "I can't be bothered to take the test, so I'll just say I passed it." No need to cheat, just provide no verifiable evidence and complain about the test. If you read that from someone else, would you believe it?
Yes, that could be done - even I could do it. Analyze instead of listen to the Foobar output. That would be easy with tones, a lot harder with music. I can't see the waveform or spectral differences in music with added distortion. MAybe someone can.