Xref: utzoo sci.electronics:18300 comp.dsp:1364 Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!hp4nl!orcenl!mberg From: mberg@dk.oracle.com (Martin Berg) Newsgroups: sci.electronics,comp.dsp Subject: Re: A question about the Nyquist theorm Message-ID: <1284@dkunix9.dk.oracle.com> Date: 7 Mar 91 17:25:14 GMT References: <625@ctycal.UUCP> <11515@pasteur.Berkeley.EDU> <3463@polari.UUCP> <38839@netnews.upenn.edu> Reply-To: mberg@dk.oracle.com (PUT YOUR NAME HERE) Followup-To: sci.electronics Organization: Oracle Denmark Lines: 25 In article <38839@netnews.upenn.edu> touch@grad1.cis.upenn.edu (Joseph D. Touch) writes: >WHAT??? I saw the few posts about the time delay alledgedly IMPOSED >by using a single D/A. A little thought reveals that using 4 sample >and holds and 1 D/A removes the time delay completely, and S/H's are >cheaper than D/A's. > >S/H1 locks the D/A output for the left channel as it comes off the >CD, S/H2 does the same for the right channel. S/H's 3 and 4 grab >the values of S/H 1 and 2 just before the next set of values gets >locked in, resulting in an output completely in phase. It looks right, but have you considered that S/H-circuits actually are a specialized kind of analog hardware ? This means that you will get some added noise and distortion for every S/H you add in series with the signal. This may not amount to much, but in a time where more and more HiFi-companies exclude unnecessary circuits (f.ex.: bass/treble controls) and uses more and more sofisticated analog circuits in the CD-players, I am not sure if your idea will be usable - anyway not in 'real' HiFi CD's. BTW: does anyone know about any CD-manufacturer actually using this solution - maybe to produce cheap CP-players ? Martin Berg Oracle Denmark