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From: jroth@allvax.enet.dec.com (Jim Roth)
Newsgroups: sci.electronics,comp.dsp
Subject: Re: A question about the Nyquist theorm (CD sampling/filtering)
Message-ID: <4063@ryn.mro4.dec.com>
Date: 2 Mar 91 14:56:21 GMT
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Organization: Digital Equipment Corporation
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In article <1991Mar1.191955@maximo.enet.dec.com>, ajf@maximo.enet.dec.com (Adam J Felson) writes...
>In article <17510@milton.u.washington.edu>, whit@milton.u.washington.edu (John
>> ...other stuff deleted...

>The first CD players did NOT have oversampling.  They ran @ 44.1 KHZ with a
>pretty
>steep 20KHZ analog filter.  

This is false.

The first players were from Sony and Phillips.  The Sony DAC's ran at Nyquist
rate with analog lowpass filters.  The Phillips used 4x oversampling and
noise shaping with a 14 bit DAC, followed by a rather gentle 3rd order Bessel
filter.  The oversampling FIR filter included compensation for the slight
rolloff of the Bessel filter.

See the Phillips technical journal that appeared about that time.

- Jim