Here’s a quick tip for “toning down” a disk piezo in your cigar box guitar, if you are getting too much noise, feedback or if it is just too treble-heavy.
Try soldering a 0.01 uF (microfarad) capacitor from the positive to ground legs of the output jack. This capacitor will shunt some of the higher-frequency signal to ground, and can really help tame an overly hot piezo.
Hi just about to build my first CBG glad I found this site. Thanks for all the useful tips. Gives me great encouragement.