Tone cap on piezo...?

[rdepelteau]

Any suggestions about what size of caps to use for my piezo bridge pup?

I tried with .047 and I didn't hear much so I put on a .01, and still don't hear much brightness coming out.

[Shoewreck]

There are some different cases:
1) You are trying to connect tone cap directly to the pickup. This doesn't make much sense, because piezo impedance is capacitive. The only thing a cap may do is cut signal level and soften (just a bit) some resonances.
2) You are connecting tone cap to buffer output. It's more reasonable, but buffer impedance is usually pretty low, about 1K or even less. Let's assume it is exactly 1K. To achieve 1 KHz rolloff frequency you'll need a 1/6,3*1000KHz*0.001MR=0.16uF cap.
My advice is to use a buffer with additional 10KR variable resistor, then a 10..100nF cap (to your taste).