Thanks, Walter. That's interesting stuff, but as you say that guy was working with a very clean sine wave at a high s/n ratio. Relatively speaking, I'm trying to process some real junk.

Although I'm still interested in anyone's comments regarding doing this with a PIC, either conventional or DSP, I've started looking at general purpose switched capacitor filter ICs to use as replacements for the single op amp RC tuned bandpass filters. The thinking there is that the NE567s would probably work way better if less trash was being shoved into them.

Thanks again,

Mike