As of yet, a few things I have discovered.
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The power supply was the culprit in disabling all audio signal. (It also powers my processor/preamp)
Not sure theoretically how an AC audio signal would cancel the digital signal through the processor's power(maybe inverted phase cancellation?)
I had to run a separate power supply to get it to work. -
I have only been able to get any sound with ceramic disc caps. I've tried electrolytic caps back to back(+ - +), metal film caps, and polyester film caps.
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The more resistance, the stronger the signal is. (Because its a bigger load?)
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The capacitance didn't seem to change sound level. I used as small as a 1nf, and as much as 0.5uf with no noticable difference.
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Multiple caps in series seemed to increase the sound level just barely. While multiple in parallel greatly decreased it.
As for the variable resistor, it seemed to not make a difference. And the RLC method is for a low pass filter isn't it? I could try an LC method, but not sure how I would incorporate the resistance. Also, I've read places that a guitar's pickup is basically an inductor in series with a cap and resistor in parallel(RLC)
The op-amp circuit you describe.. by which you mean as a buffer to keep a specific resistance? That may be a good idea to try out, but would be sensitive to different pedal layouts(different IO impedance).
There also seems to not be any 20hz high pass filters available in a small package. I found this schematic however:
http://www.eeweb.com/blog/circuit_projects/20hz-to-200hz-variable-high-pass-filter
May be useable, but the schematic states 15v input voltage, and the tl072 is rated ±15v.
Could I just swap for a lower voltage chip, or just run this with 9v?
Thanks for the help Far-seeker, you have really helped me out so far.