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Path: utzoo!linus!decvax!genrad!mit-eddie!godot!ima!inmet!muller
From: muller@inmet.UUCP
Newsgroups: net.audio
Subject: Re: re: West of Oz CD
Message-ID: <1727@inmet.UUCP>
Date: Tue, 16-Oct-84 02:36:19 EDT
Article-I.D.: inmet.1727
Posted: Tue Oct 16 02:36:19 1984
Date-Received: Wed, 17-Oct-84 19:55:01 EDT
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Nf-ID: #R:decwrl:-387200:inmet:2600110:000:1987
Nf-From: inmet!muller    Oct 14 22:33:00 1984

***
Nice experiment, trying the blind comparison.  A few comments, questions, and
suggestions:  (1) You say analog to digital sounds good, but digital to analog
sounds bad.  Then you ask why.  Umm...seems to me that this is a bit of a
generalization.  As I try to answer this to myself, and as I ponder the results
of your PCM test, I find lots of room for any specimen to be poorly done, but
no reason to explain why A to D is ALWAYS better than D to A.
(2) With regards your piano and guitar recordings, why not try the same setup,
recording the same stuff into a GOOD analog tape machine?  THEN do a comparison
of the two recordings PCM -> VCR vs. Analog tape.  You will probably hear some
differences, but the audible features you describe as characteristic of digital
may be present to some extent in your analog recording.  What might they be?
  Well, maybe what you heard is exactly what your mics heard.  A look at most
mics' spec sheets shows definitely non-flat frequency response.  They were
designed (evolved?) to sound good, not necessarily have flat-looking response.
Perhaps they compensate for other features of the recording medium, features
which digital systems don't quite duplicate?  (Can we assume there was no real
loss of information in the VCR, such as lost bits that were only poorly "fixed"
on playback?  (I don't know much about how VCR's work.))
(3) Have you, or anyone else, dont this same PCM -> VCR test using pink noise
and an analyzer?  Yeah, I know, you can't really expect .5 dB precision from
this, but it sounds like we are talking about more than this anyway.
...
   Looking objectively at your results, you have shown that the digital process
itself is not really making things sound bad.  So where then is the problem?
It must elsewhere in the recording process, either the total composite 
frequency response, or the dynamic range, or non-linearities or so
Thus it would be good to try the other recordings I suggested, just as another
control.