Quote Originally Posted by koldo2552 View Post
Piezo disk acts as a contact mic, and as a mic you will have to be careful about feedback if you turn up the volume. But you can put it under control with a litle eq or a notch filter.
Also, as a mic, it will catch all the hits you give the body, i find it interesting for percussive sounds. That's the reason i hit the body in the video in diferent places.

If you have some kind of preamp lying around, a piezo disk for about 1$ is the perfect add on for an acoustic or electric guitar...
I have a piezo disc in my cigar box guitar and if you not careful the guitar becomes a stompbox more than a usable slide guitar.