muller@inmet.UUCP (04/21/84)
#N:inmet:2600067:000:930
inmet!muller Apr 20 22:48:00 1984
****
One criticism against CD's has been that the placing of data from
the two channels in an alternating pattern causes phase shifts
between the channels. These shifts, which would be negligible for
low frequencies but would be pi/2 for Nyquist frequency, allegedly
interfere with the spacial image on the reproduced soundstage.
Question is: Are the original samples TAKEN that way? If so, it
would render this criticism mostly invalid. Does anyone out there
know the answer to this?
Since it would depend on the hardware used, it may be that some A to D
conversions are done this way and some are not. Thus some recordings
might suffer from this malady while those from some more enlightened
source wouldn't. This question would apply even to those made from
digital original tapes, since microphones are all analog.
Anybody know? Thanx, Jim Muller
ima!inmet!muller or harpo!inmet!mullermuller@inmet.UUCP (04/24/84)
#R:inmet:2600067:inmet:2600068:000:533 inmet!muller Apr 22 18:41:00 1984 *** Answer to my own question...thanx to someone else's prompt response: It isn't necessary, b'cuz it can easily be done with a FIFO buffer on playback. I was actually interested in how it IS done in practice. I suppose each manufacturer of CD players can do what he wants about this alleged problem. The answer, of course, is obvious. I am not a hardware/implementation person, nor familiar with the CD format; I'm just a lowly equation pusher...so couldn't be expected to think of such an elegant (i.e., easy) solution.....
edhall@randvax.UUCP (04/24/84)
+ The phase shift you are talking about is actually a time delay, and amounts to the same amount of delay you would get by moving your head about 1/16th of an inch off-center. You can compensate for it by moving one speaker (I'm not sure which) about 1/8th of an inch in front of the other one. But unless you have your head clamped in a rigid position for listening, you'll completely swamp this effect by head movement. Headphones might be another matter, but I'm sure some audiophile concern will market spacers at some point... Of course, all this ignores that a 12us delay is way below the level of perception (as I'm sure rabbit!jj will remind you). -Ed Hall decvax!randvax!edhall