Onboard Tone Control + Preamp?

[Shannon]

Well, I've been wanting to put an active circuit in the control cavity of my electric guitar for awhile now. Originally I just wanted to throw a buffer in, then I came across Mark Hammer's flexible EQ. Lately I've been playing with the idea of combining this with a Discrete FET Preamp and replacing the conventional tone control in the guitar. My only trouble is working out some of the component values. Here's what I've got so far:



Obviously, the 500k pot is the tone pot. Would I just use the standard 0.047 or 0.022uF for the cap after that? What about the other components in red?

Thanks.