[Somnambulist]

I read this thread from start to end in the early hours of last night. Gregorio should be praised for his consistently informative posting and his patience dealing with certain posters. Some of it went over my head from a technical standpoint, but I 'get the gist' of it and it'll surely help me with DAC choices in future.

 

[nick_charles]

Cough... Meyer and Moran 2007 ?... empirical evidence that stripping the upper (22k+) harmonics may be in fact be inaudible in playback, not as yet refuted by any latter empricial tests...

 

[andysor]

Thank you so much to Gregorio for his extremely informative and easy to follow OP and considerable patience, even when confronted by personal attacks from people intent on defying mathematical logic in favour of clinging to their placebos.
 
After reading most of this thread I have saved myself from a future of unnecessary outlays and will be focusing on enjoying the music.

 

[kingtz]

 
 
Thank you! This was very educational and opened my eyes!

 

[Deep Funk]

In my search for a DAC this thread will prove valuable.

 

[mike1127]

Others have said it here---Nyquist sampling theory is just theory, and reality is notorious for not conforming to theory.
 
The 44.1 KHz sampling rate was chosen on the idea that humans can't hear much about 20 KHz (or even 15 KHz). If you play a human a tone at 22.05 KHz, they can't hear it. But there's an assumption here---that the ear is a linear system. It's not.
 
Say we have two impluse-like signals A and B. Maybe two recordings of rim shots. Further suppose that when Fourier-analyzed they are identical at frequencies below 20 KHz. But they differ above 20 KHz.
 
Can the human ear tell these apart? If the ear were linear, we can settle that question immediately: nope. But the ear is nonlinear.
 
I'm pointing out that these are distinct statements:
 

1. No one can hear at 22 KHz tone.
2. No one can tell the difference between impulse-like signals A and B which differ only in harmonic components above 22 KHz.

 
Because the ear is nonlinear, one does not imply the other.
 
Note that any A/D D/A system that incorporates any kind of filtering or processing that is unrelated to how natural-world system behave, will exhibit a transient response that is unlike anything in the natural world. Infinite impulse-responses (especially that have energy before the leading edge) are examples. I wonder if this explains a lot of the problems with digital.

 

[nick_charles]

 
Quote:

 
Can the human ear tell these apart?
 

The best evidence we have is that the answer is no. This has been done frequently since the late 70s with filters removing harmonic content being undifferentiable from the unfltered content or inserting AD stages to remove 22K+ material;. You can try it youself, take a 96khz file and then low pass filter off the content above 22K and do a FooBar ABX. There are numerous anecdotes about the effect of higher harmonics but the empirical evidence to date just does not back this up.
 
 

 

 

[Pio2001]

A more direct experiment : play a 12 khz tone in your left speaker, and a 18 khz one in your right speaker.
Then do it in mono.
Be careful not to fry your tweeters if you try it at home.
 
This kind of experiment, much more likely to reveal any relevant non-linearity than any musical content, has been done independantly by David Griesinger, by Nika Aldrich and by myself. Our results match : extended frequency response, though usually inaudible, can become audible using this kind of exceptional test tones, and the result is that the frequency extension increases distortion, because in this special case, thanks to the deafness of the ear at upper frequencies, the hifi system introduces more non-linear distortion than the ear !
 
David Griesinger's experiments seems to show that the intermodulation comes from the amplifier rather than the tweeter.

 

[hscai]

Thank you for the interesting and quality write-up. Unfortunately, I've been lazy recently, and have rarely read an article through completely and thoroughly - this one is an exception! That goes for the interesting comments in this thread as well.

 

[dedero]

Hello guys,
 
After reading this article I will ask you a newbie question.
 
After seeing that Apple (Beatles) release a USB stick with whole discography in 24/96, can this new format give a bigger gap to allow The Beatles still "fighting" in loudness war? (I'm asking for the beatles just to put an example, it applies to the other bands)
 
Thanks
 
Bruno.

 

[leeperry]

 

 
After seeing that Apple (Beatles) release a USB stick with whole discography in 24/96, can this new format give a bigger gap to allow The Beatles still "fighting" in loudness war?

 
CDDA can provide 96dB of dynamics...the weak link is not the medium, it's the record companies that ask the mastering engineers to make it loud...because ppl want it to be loud, as they'll listen to it on their ipod.
 
I've heard the Beatles 24/96 USB key, SQ is clearer than on the CDDA versions...but it's still very much bloated to my ears. Compare those versions to the CDDA mastertape bootlegs that are floating around, and they sound processed/EQ's/compressed to death. But more than likely if they had released "audiophile" versions of those records, ppl would have whined that the sound was dull and lifeless.

 

[Deep Funk]

That would mean the 16 bit digital CD remasters are still better right? I prefer CD anyway...
 
DACs, confusing too. Maybe a studio oriented DAC will cross my path in time...
 

 

[kwkarth]

Quote:

That would mean the 16 bit digital CD remasters are still better right? I prefer CD anyway...
 
DACs, confusing too. Maybe a studio oriented DAC will cross my path in time...
 

Again, it's not the medium that is the problem.  If the mix-downs that are committed to release are compressed/processed to death for AM radio's sake, nothing you can do will make it better.  Even dynamic range expanding will not unscrew it.

 

[lucozade]

Quote:

While I don't completely understand all of the details of this ongoing debate as reflected in this thread, I do get the jist of it, and what you are saying makes sense to me. It also makes me trust my own conclusions, that the most important thing is the quality of the source recording and mastering, regardless of the bit rate and sampling frequency used for playback. Anyways I do appreciate all of the thoughtful posts lately, it's very interesting subject but sometimes it just makes me want to play a record!

 x2 

 

 

[Deep Funk]

X3, it is time for some music. 
 
Kwkarth, yes I know that. Now all I can hope for is that bad pressings and bad mix-downs do not cross my path too often. Thanks anyway for clearing that up. That does imply that for hunts on the next CDs I will have to do more digging. Judas Priest already gave me head aches...