SACD vs. CD - Unfair competition?

[Smokey]

As you said before, the issue about audibility is not going to be solved here, so why should I continue to talk about redbook CD vs. higher resolution media?

Thomas, issue here might not be the audibility of signal, but rather the integrity of it. As Sir TT mentioned, by filtering at 22 kHz, transient harmonics and sub-harmonics of signal might be effected and filtered out which are above 22 kHz.

Instead of providing complicated graphs of noise, dynamic or resolution figures, how about going back to basics of filtering on this issue which will shed some light on it. Here is an example:

Suppose we have a 20 kHz low pass filter and we run a 10 kHz square wave thru this filter. Common sense dictate that we will get a 10 kHz square wave out this filter since the cut off frequency is at 20 kHz. But that is not true. What we will get out this low pass filter is not a square wave, but a 10 kHz pure sine wave instead of square wave.

Since 10 kHz square wave is a combination of pure 10khs sine wave and infinite number of odd harmonics that are way beyond 20 kHz, then by filtering the harmonics that are above 20 kHz, we altering the integrity of signal.

The same argument can be applied to complex audio signals that contain many harmonics that are beyond 20 kHz. By filtering the signal around 22 kHz which CD red book does, we might be filtering out transient harmonics and sub-harmonics (which define its character), thus making the recording sound "cold" and too sanitized.

By moving the filtering to 44 kHz or 100 kHz for DVD-A or SACD, the integrity of signal is preserved, giving the sound quality a full, warm, sweet sound we are used to hearing in a live situation.

[Thomas_A]

Thomas, issue here might not be the audibility of signal, but rather the integrity of it. As Sir TT mentioned, by filtering at 22 kHz, transient harmonics and sub-harmonics of signal might be effected and filtered out which are above 22 kHz.

Instead of providing complicated graphs of noise, dynamic or resolution figures, how about going back to basics of filtering on this issue which will shed some light on it. Here is an example:

Suppose we have a 20 kHz low pass filter and we run a 10 kHz square wave thru this filter. Common sense dictate that we will get a 10 kHz square wave out this filter since the cut off frequency is at 20 kHz. But that is not true. What we will get out this low pass filter is not a square wave, but a 10 kHz pure sine wave instead of square wave.

Since 10 kHz square wave is a combination of pure 10khs sine wave and infinite number of odd harmonics that are way beyond 20 kHz, then by filtering the harmonics that are above 20 kHz, we altering the integrity of signal.

The same argument can be applied to complex audio signals that contain many harmonics that are beyond 20 kHz. By filtering the signal around 22 kHz which CD red book does, we might be filtering out transient harmonics and sub-harmonics (which define its character), thus making the recording sound "cold" and too sanitized.

By moving the filtering to 44 kHz or 100 kHz for DVD-A or SACD, the integrity of signal is preserved, giving the sound quality a full, warm, sweet sound we are used to hearing in a live situation.

But all this means that e.g. there should be an audible difference of 10 kHz squarewave and a 10kHz sinewave, right? There is no evidence of humans hearing above the 22 kHz, regardless whether it is harmonics in music or signals. There is one reference by Oohashi in J. Neurophysiology, but it contains many questionmarks around the method used. The ppt. file above have some more info.

The possibility remains that high frequency content mixes with with each other creating tartini tones of lower frequency, but I've done the tests and it very high levels even to be faintly audible when testing a tone of e.g. 20 kHz (inaudible for me) and 19.5 kHz (which should give difference tone 500 Hz in the ear). It is unlikely that anyone would ever hear difference tone distorsion (as created in the ear) if high frequency content above 20 kHz for music.