MattiasOfTheMetal:
But the minimum load can be as low as a few hundrew ohms (volume control) or less.
The new guitar I am installing this into(hopefully) will have selective bypass resistance which will cut out of the pickups.
I forgot to include that info originally, since I was testing it on my currently built guitar.
Yeah that is something worth knowing ahead of time... The fact that there is a variable load with a range of over tens of thousands of Ohms does complicate designing a passive filter. Do you have a potentiometer avaialble in the range of 20k to 50k ?? If so wire it up as a variable resistor in series with your guitar's load and use that to keep near a specific resistance that yields a desired cut-off frequency with the capacitor(s) you are using. Alternatively, it might be worthwhile trying a RLC high-pass filter with your guitar's load as the resistive element. Finally, there's always the possibility of making an active circuit using an op-amp but that shouldn't be necessary just seperate a sinusoid from a DC offset.
One minor thing, unless you know the pedal board output will have an unwanted DC or very low frequency signal you might remove C1 for now just to simply the circuit.