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Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!decvax!bellcore!mouton!karn
From: karn@mouton.UUCP
Newsgroups: net.audio
Subject: Re: Nakamichi OMS-7/OMS-5 Compact Disc Players
Message-ID: <226@mouton.UUCP>
Date: Mon, 10-Dec-84 02:14:32 EST
Article-I.D.: mouton.226
Posted: Mon Dec 10 02:14:32 1984
Date-Received: Thu, 13-Dec-84 03:05:16 EST
References: <181@decwrl.UUCP>
Organization: Bell Communications Research, Inc
Lines: 31

Hate to beat a dead horse, but I thought I'd throw out this fuel for
the fire.

I recently obtained the service manual for my Technics SL-P7 CD player.
You know, one of the "el cheapo" models with (horrors!) analog reconstruction
filters, and (double horrors!) a single D/A converter. All in all,
a unit that "gives digital audio a bad name" (to quote one of the net
experts).

In scanning the schematic, I immediately noticed some assymetry between
the two channels. It turns out that they put in an ANALOG all-pass filter in
the left channel whose sole function it is to delay the signal by 1/2 sample
to make it "match" the right channel.

So there. They saved me the tedious effort of moving my left speaker back by
a centimeter or so.

Phil

P.S. I recently attended a live performance of Saint-Saens Organ Symphony
given by the Baltimore Symphony Orchestra. Compared to my reference
CD player, the live performance lacked proper stereo imaging and had
shrill, harsh highs. The noise level was also considerably higher (no
audience should have been allowed) and there was obvious multi-miking
in the acoustic design of the concert hall.

(Seriously though. The live concert made me realize how far we've
come in sound reproduction. Except for the audience noise, I could close
my eyes and imagine myself sitting at home in front of the CD player.
So why did I blow $16.50 per ticket?)