Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!csd4.csd.uwm.edu!info-high-audio-request
From: sethb@fid.Morgan.COM (Seth Breidbart)
Newsgroups: rec.audio.high-end
Subject: Re: DAT degradation
Message-ID: <12617@uwm.edu>
Date: 30 May 91 13:00:14 GMT
Sender: news@uwm.edu
Lines: 44
Approved: tjk@csd4.csd.uwm.edu
Originator: tjk@csd4.csd.uwm.edu


In article <12579@uwm.edu> kls30@duts.ccc.amdahl.com (Kent L Shephard) writes:
|
|I recently purchased a Pansonic SV-3700 Pro DAT machine.  Now supposedly
|you can copy a DAT and get the same quality on the copy.  Now looking
|at the way the data is transmitted and calculating the probability of
|uncorrected errors being transmitted to the receiving deck I would say
|that no degradation in quality would occur.  This is  using the AES/EBU
|pro outputs with balanced XLR connections and not the S/PDIF standard with
|unbalanced lines. On the other hand I have a person that says that
|degradation will be audible in the fifth copy.  So audible that he can't
|stand to listen to it.  I say he doesn't know what he is talking about.
|I'm hold a BSEE and am about to complete a MSEE.  The person I'm arguing
|with holds no degrees and doesn't understand any signal processing theory
|or probability.  He says he knows it will happen.  I said that we need
|some other opinions or reliable data.
|
|So has anyone actually done about 5 generations of copiy upon copy?

I've made over 5 generations, starting with a tape that was already
several generations "deep".  There was no audible degradation.

All of these copies were made via the rca connectors, using S/PDIF
signals.

One of the common test cd's has a passage which was made from a master
tape, followed by the same passage made from the 100'th digital
generation of that same tape.  Why don't you copy each of those onto a
dat tape several times (in random order), and challenge the person you
referred to above to tell the difference?

A study recently done by one of the pro audio magazines (Mix?) found
that a 20'th generation analog copy is sometimes (depending on the
type of sound) identifiably different from the first generation.

|Also could someone tell me the actual function of some filters that seem
|to be popular in A/D conversion called apogee (sp?)filters.  Supposedly
|the do anti-aliasing and do something to retain the warmth of analog
|recording what is this something else.

A company, Apogee Electronics, makes replacement filters for a/d
converters.  They also make an outboard a/d converter.

Seth		sethb@fid.morgan.com