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In Reply to: RE: This are honest questions............... posted by jrlaudio on November 03, 2012 at 04:39:19
and what we really know about accurate musical playback.
You wrote:
"Human hearing, at best can discern SPL changes at an absolute limit of about 1.5dB SPL. Time differences can be heard to just above 10 microseconds. Phase down to about 1 degree."
Where have you been hiding? Amplitude changes are recognized to be audible at 1 dB, and James Johnston once posted in this very forum, that he thought that under certain conditions, differences of 0.5 dB could be discerned.
Time differences down into the fractional millisecond range can be discerned. Why, with very little trouble, I was able to create a test signal where just about anyone can hear the change in timing of one sample of digital audio at 44.1 kHz. That's 0.02 milliseconds.
Actually, we can hear even smaller amounts of timing differences, but I can't find the reference to the paper right now.
But the bottom line is, all of that is completely beside the point.
No one has yet to truly create a solid correlation between what we hear when one component has a wide and deep soundstage, and another sounds flat, scrunched and two dimensional by comparison.
In other words, there is no soundstage meter, nor any way of determining why one components kicks _ss and another blows at creating a realistic soundstage.
What measurement can tell us this?
THD?
IM?
S/N ratio?
WE JUST DON'T KNOW!
I am NOT saying it can't be measured, or that we will never be able to do so, but that right now, we don't know what parameter or combination of parameters defines soundstage maintenance.
That's not the only thing we can't measure either.
Most of the measurements we have are geared toward steady state signal conditions, while by the very definition of music, the musical signal is constantly changing and consists mostly of transients.
How do we measure the "blackness" of a sound stage background? S/N might seem to be relevant, until we remember, that in order to hear the lack of or capability of hearing no extraneous noise or signal modulation immediately before and after a note or transient, THERE FIRST HAS TO BE A NOTE OR TRANSIENT! Conventional S/N measurements are completely blind to this sort of audible performance, and inherently CAN'T provide any sort of reliable metric regarding such extraneous dynamically varying noise.
At the very least, there is no standardized measurement technique, or test gear or methodology that can be called into play to do these sorts of things. You actually have to LISTEN in order to hear and evaluate these aspects of musical playback.
As far as the rest of the conventional and typical measurements, tell me that THD is relevant in today's world of super-low distortion amps, where the amp with the lowest THD often sounds the worst of the lot, and the amp with 1 and 2% THD sounds musical and sweet and causes no listening fatigue for hours of listening.
Since most folks have moved on past the simple metric of THD, but instead, are looking at the harmonic structure of the distortion, rather than a single number figure of merit, the problem then becomes that of what sort of weighting do you use?
Just about everyone agrees that the higher order harmonics are less desirable, and therefore, they should be weighted to be more of a contribution to the overall figure of merit, but which weighting? Squared?
Cubed? Use the Cheever formula?
Even here where we maybe have half a clue that THD is bogus, and the harmonic structure is much more relevant, we don't know what kind of weighting to apply to the harmonics, in order to determine, which of two different harmonic structures is more desirable.
Once again, if we are honest with ourselves, WE DON'T KNOW!
So while we may (or may not) know what the limits of human hearing are, we certainly don't know all there is to determining what parameters are necessary to create an audibly distortionless playback system.
Time and time again, a system has been assembled, and all the individual components met the criteria of that decade, and it still fell woefully short of realistic playback.
To try and state with absolute certainty, that all we have to do is measure the components, and we know what they will sound like is folly and arrogance beyond belief.
Jon Risch
Follow Ups:
"How do we measure the "blackness" of a sound stage background? S/N might seem to be relevant, until we remember, that in order to hear the lack of or capability of hearing no extraneous noise or signal modulation immediately before and after a note or transient, THERE FIRST HAS TO BE A NOTE OR TRANSIENT! Conventional S/N measurements are completely blind to this sort of audible performance, and inherently CAN'T provide any sort of reliable metric regarding such extraneous dynamically varying noise."
In light of these comments, you might find the video talk linked below to be interesting. It shows how people heard unmeasurable problems with sigma delta modulators and how better measurements were discovered to show the problems that some people were hearing. The end result was a new modulator that (supposedly) sounds better.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Stu
AND IN CONCLUSION - WE JUST DON'T KNOW.
So let's all go back to the Cable Asylum and Isolation Ward and discuss our impressions in a creative, friendly, and positive way!
Thanks Jon for setting us all on the path to righteousness and salvation!
The Cable Asylum is not the proper venue for objective discussion or measurement analysis.
That is what Prop Head is for.
However, given your posts here, and in other portions of the Asylum, you already have made up your mind, and would only seem willing to argue for the sake of argument. Of course, the urge to "save them from themselves" is also a factor for you and your ilk, but as I said before, no one there needs "saving".
Jon Risch
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