Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!gatech!gitpyr!byron From: byron@pyr.gatech.EDU (Byron A Jeff) Newsgroups: comp.dsp Subject: Re: More digital mixer stuff Message-ID: <9241@pyr.gatech.EDU> Date: 29 Sep 89 22:37:37 GMT References: <9238@pyr.gatech.EDU> <1989Sep29.102204.8798@ivucsb.sba.ca.us> Reply-To: byron@pyr.UUCP (Byron A Jeff) Organization: Georgia Institute of Technology Lines: 66 -~[Byron] -[Todd] -~Even if it were serial I'd probably just shift it into shift registers -~and read in the parallel outputs when all of the bits of a complete -~sample has been shifted in. - -What I was refering to was the *built-in* serial shift registers in -the DSP chips. That way, you wouldn't need the glue logic. But as you stated it's only one channel unfortunately. If the design decision comes down to a choice of TI, 2 56001's, or external shift registers with a single 56001 I'll probably go with the external glue. How can I lose at $0.59 a pop? ;-) However if I turn out to need 2 56001's do handle the processing then I'll use the internal shift registers. I'm working on a shared memory controller between two 68008's and a 68010 right now for my kick-ass MIDI box. I might be able to apply it here somehow. - -~>Remember that since you are using an analog MUX, the samples can't all -~>be done at EXACTLY the same time, so there will be a slight delay between -~>all of the channels. -~I'm brand new in this domain. I have no clue what the effect of the -~delay between channels will be. Can you give me an idea? - -Ch 1 - delay - Ch 2 - delay - Ch 3 - delay - Ch 4 - -The delay will be the length of time it takes to switch from one -channel to the next via the MUX and then sample with the sample/hold. -Probably not very signifigant, but those who spend $1000 on interconnects -for their stereo systems would probably complain. Of course, they wouldn't -be listening to digital, anyway, would they? :-) I'm hoping it's not significant. And I can't hear the phase shift when I reverse polarities of the Monsta Leads to my $4000 Polk Audio speakers either ;-) - -~Another reponse I saw indicates that a 56001 wouldn't be able to handle -~mixing 8 channels much less doing any kind of EQ, reverb, etc. He -~suggested a DSP for each channel. - -I know that one chip can *at least* emulate a 2 channel 10 band 12 dB -equalizer from a Motorola app note. I wouldn't think that reverb would be -that tough to do. Good to hear. I could live with effects on the mixed signal even though having individual effects on each channel would be cool. Not worth eight 56001's cool though. - --- - -Todd Day | todd@ivucsb.sba.ca.us | ivucsb!todd@anise.acc.com -"Ya know, some day these scientists are going to invent something - that can outsmart a rabbit" -- Bugs Bunny After reading your series on building a beast and your discussion so far on this mixer I feel very optimistic about the idea. Thanks. 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