Sampling and Nyquist/Antialiasing filters

[Duane R Balvage]

Hello all -

Is there anyone out there who has any basic guidelines on how many dB

down "aliasing" frequencies have to be so they are not a problem?

I'm retrofitting my Prophet-2000 sampler with 2 switched-cap

6-pole filters in series (12 poles, 72 dB/oct) for the antialiasing

filter. (The antialiasing filters in it now are a bit, uhh, conservative
 
to say the least) Right now they sit at:

41Khz sample rate : 16Khz corner freq.

32Khz sample rate : 12Khz corner freq.

24Khz sample rate : 9Khz  corner freq.

They are using 4 pole input filters (I think - have to check the schems)

so the slopes are a bit gradual, taking off some of the "sparkle" of

the samples because they have to have their corner frequency set low 

enough to avoid aliasing. Any suggestions???

					- Duane
-- 
   "That boy's got a mouth like a cannon ... Always shootin' it off..."
                                
                             - Foghorn Leghorn
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