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From: agn@cmu-cs-k.ARPA (Andreas Nowatzyk)
Newsgroups: net.audio
Subject: Re: Carver CD Player & Technology
Message-ID: <332@cmu-cs-k.ARPA>
Date: Fri, 22-Mar-85 16:23:57 EST
Article-I.D.: cmu-cs-k.332
Posted: Fri Mar 22 16:23:57 1985
Date-Received: Tue, 26-Mar-85 05:29:28 EST
References: <14700008@hpfcms.UUCP> <5000001@hplsle.UUCP> <474@harvard.ARPA>, <2515@tekig.UUCP>
Organization: Carnegie-Mellon University, CS/RI
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I hope cancel worked, otherwise please excuse my empty post. This was
caused by our job-security program for UNIX system maintainer: they
keep on moving EMACS to strange locations...

On the subject on 4X 14bit vs. nX 16bit (n=1,2,4):

4x oversampling with 14bit is theoretically equivalent to 16 bit *if*
the 14 bit DAC has 16 bit precision (that is, if it is equivalent to
a 16 bit one that has its 2 lsb's tied to some constant). However, this
is not the case. See the IEEE Journal on Solid State Circuits, Vol SC-14,
pp. 552-556 for an interesting paper on the Philips 14bit DAC. At 25C,
it approaches 15bit precision, but over the entire temperature range it
is just a good 14bit DAC. They also claim a S/N of 'only' 90db while
16bit could approach 96db. At the time of the design (arround 1979), it
was not feasable to integrate a 16bit DAC without expensive laser trimming.
So part of the reason for 14bit is plain cost reduction.

On the subject of ringing:

Ringing is a characteristic of a particular filter design and has little
to do with the components used ('capacitors'). A given n-pol filter
design has a certain ammount of ringing, no matter of its realization:
analog or digital. Digital filters however can be designed to have
better performance by the use of a large number of poles. The Philips
design has something like 64 poles while the one in Sony's D5 has
9 (if I understand the circuit correctly). The number of poles in
an analog filter is limited by the number of discrete parts involved
and by their precision. The number of poles in a digital design is
limited only by the number of gates you can afford.

Cheers, Andreas            Usenet: ...!seismo!cmu-cs-k!agn
			    Arpa:  Andreas.Nowatzyk@cmu-cs-k.arpa