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From: sjc@mordor.UUCP (Steve Correll)
Newsgroups: net.audio
Subject: Re: No. of D/A converters, some players...
Message-ID: <3569@mordor.UUCP>
Date: Wed, 18-Sep-85 13:01:23 EDT
Article-I.D.: mordor.3569
Posted: Wed Sep 18 13:01:23 1985
Date-Received: Fri, 20-Sep-85 04:45:45 EDT
References: <561@petrus.UUCP>
Distribution: net
Organization: S-1 Project, LLNL
Lines: 26

>  I have learned that the D/A converter in the cd player is the thingy that 
> takes the cd disk information and converts it into music. Now, I have also
> heard that:
>  		1) Having two is fairly important
> 		2) Not having two doesn't really make a difference.
> 
>  What are the other opinions out there (and why)?

I firmly believe every CD player should have at least one D/A
converter. A player with only one must switch the output of the DAC
alternately between the left and right channels, probably using a FET
analog switch. Two oft-stated objections to this are that it delays one
channel compared to the other, and that it introduces transients. The
answer to the first objection is that the delay is uniform and
equivalent to sitting 1/3 inch closer to one loudspeaker than to the
other; few of us position ourselves on the sofa with this much accuracy
to begin with. The answer to the second objection is that the A/D
converters used in generating the CD in the first place may well use
similar analog switch technology; that the transients are so high in
frequency that the post-DAC filter (often called, loosely, an
"anti-aliasing" filter) gets rid of them along with the images generated
by the sampling process; and that it is in the nature of the DAC itself
to generate similar transients.
-- 
                                                           --Steve Correll
sjc@s1-c.ARPA, ...!decvax!decwrl!mordor!sjc, or ...!ucbvax!dual!mordor!sjc


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