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From: fish@ihu1g.UUCP (Bob Fishell)
Newsgroups: net.audio
Subject: Re: CDs don't you just love them??
Message-ID: <428@ihu1g.UUCP>
Date: Tue, 12-Jun-84 12:25:24 EDT
Article-I.D.: ihu1g.428
Posted: Tue Jun 12 12:25:24 1984
Date-Received: Wed, 13-Jun-84 01:03:10 EDT
References: <4@sunybcs.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 29

Square wave response in CD players varies with the type of filtering
used.  In general, those with digital filters tend to produce square
wave responses that are less ragged on top.  However, it has to be
pointed out that musical instruments don't produce square waves, and
that square wave response is, at best, a very rough measure of the
frequency response of a system.

If you want to see some ugly square waves, hook up a function generator
to your amplifier, put some low-amplitude square waves through your
system, and hook the 'scope up to a microphone placed at any convenient
distance from your speakers.  That's right, *your* speakers; I don't
care what kind they are or how much you paid for them.  You will see
"square" waves that are considerably more distorted and ragged on top
than any CD player produces.  Does this mean your speakers are no good?
Of course not, for the very reasons mentioned in the preceding
paragraph.

I don't know why you digiphobes don't appreciate CD technology, but I
do know that none of you has yet come up with solid technical evidence
for the abberations you purport to hear.  Yes, there's a phase shift
with multipole Butterworth filters, and yes, there's a sharp rolloff
above 22 Khz.  However, the fact remains that most people can't hear
whatever effects these phenomena produce.  Now, I believe that you
really don't like what you hear from CDs, but you'll have to do a 
little better than citing poor square wave response as a reason.
-- 

                               Bob Fishell
                               ihnp4!ihu1g!fish