A contact mic can be fashioned from pretty much any piezoelectric buzzer. On Ensemble’s good friend, Charlie Campagna, gave me a stack of them he picked up at a surplus shop. You can get new ones online, at Radio Shack, or better yet, by recycling them from old electronics.

I installed a 1/8″ phono adapter from a walkman into the melodica itself and a break-out cable that goes from 1/8″ male 90 degree plug (3.5 mm mono TS) to 1/4″ female to accept a standard 1/4″ guitar cable.  I pulled the 1/4″ female TRS jack from a broken headphone amplifier and installed it in a tiny plastic container I had sitting around.

Surprisingly, the signal out of piezo elements is strong, so you can test by plugging it directly into any RCA input.  If a single contact mic is unable to pick up the instrument’s full sound, multiple contact mics can be connected in parallel.

Hot glue is a great way to attach the contact mic semi-permanently to wood, plastic, and metal surfaces. Solder all the wiring first, as the hot glue melts at a lower temperature than the solder. Use a dab of hot glue about the size of a dime and press the contact mic securely into the glue. The contact mic will quickly transfer the heat of the hot glue and become too hot to touch, so press with a piece of cardboard to protect your fingers.

Happy hacking!