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From: byron@pyr.gatech.EDU (Byron A Jeff)
Newsgroups: comp.dsp
Subject: Re: More digital mixer stuff
Message-ID: <9242@pyr.gatech.EDU>
Date: 29 Sep 89 22:46:00 GMT
References: <9238@pyr.gatech.EDU> <1989Sep29.102204.8798@ivucsb.sba.ca.us> <1160@lakesys.lakesys.com>
Reply-To: byron@pyr.UUCP (Byron A Jeff)
Organization: Georgia Institute of Technology
Lines: 34

-[Todd and my discussion on delay]
-
-Well, the delays would be eliminated if you used 4 sample & holds, up before
-the analog demux, no?  Simply "hold" all 4 signals at the same time, and then
-demux them after they are frozen, then unhold & repeat the sequence.  Of
-course, the other solution would be to have separate A/D's for each channel,
-as has been suggested in an alternate thread of this same subject.

I'm trying to maintain a minimum parts count on the box since I'm going
to wire the prototype by hand. Separate ADCs eliminates the need for the
200Khz speed on the part at the cost of board space, wiring, and cost.
The 4 S/H however is quite a viable solution. I'll probably run tests
in the delay configuration and see what effect is has. If it's absolutly
Godawful then I'd try the 4 S/H next.

-
-BTW, isn't this "delay" the same "problem" that's been mentioned with certain
-CD players, which use only one D/A converter for both channels, but mux the
-stereo outputs?  One person (in a review I read) gave the analogy of standing
-1 cm closer to one of the stereo speakers in the room while listening to a
-CD, as being the effect of this phase shift (i.e., the speed of sound vs. the
-delay).

That's why I'm not going to worry about it 'til I hear a problem with it.

-   - Mike Shawaluk 
-       (mikes@lakesys.lakesys.com  OR  ...!uunet!marque!lakesys!mikes)

BAJ
-- 
Another random extraction from the mental bit stream of...
Byron A. Jeff
Georgia Tech, Atlanta GA 30332
Internet:	byron@pyr.gatech.edu  uucp:	...!gatech!pyr!byron