• how to make a contact mic

    October 24th, 2006

    So, you want to make a contact microphone? Whether you want create noise music by banging on scrap metal, cheaply and easily amplify your acoustic instrument, or just play with wires, you’re in the right place. You will need:

    • piezo transducer (radioshack 273-073A)
    • 1/4″ audio cable (eg radioshack 42-2381A)
    • tape, solder, hot glue, heat shrink tubing, etc

    That’s all! It’s pretty simple an inexpensive: two piezos and a six foot cable cost me ten dollars and yield two mics. You also probably going to use pliers, a razor blade, and a soldering iron or hot glue gun if you have them. Kids, we’re playing with things that are hot and sharp, so don’t tell your parents or they’ll get all up in your shit.

    Ok, there are our ingredients.

    Break the tabs off of the transducer with the pliers, then crunch off the plastic. Be somewhat careful – remember that there’s a thin brass wafer inside that you don’t want to destroy.

    I ended up sticking my needlenose pliers in the hole and just pulling off the plastic on that side, then twisting away the side wall.

    There we go, the piezo is loose.

    Cut the cable in half. Moving from the outside in, the cable cross section looks like this: black rubber, wires, clear rubber, wires.

    Starting about an inch from the cut end, use the razor to slice along the cable, making sure to cut as shallowly as possible. You want to break through the black outer insulation while cutting as few of the copper wires as possible. Then, pull the rubber off to one side, again trying not to break the wires, and cut it off.

    Now gather all of the wires to one side and twist them together. It doesn’t matter if you lost a few, your mic will be alright.

    Strip the exposed center wire. It’s a good idea to leave a quarter inch or so of clear insulation at the base to keep the two lines separated. While you’re stripping that wire, you might want to expose a little more metal on the lines coming off of your transducer, too.

    Now you need to connect the two piezo wires to the two cable wires. Twisting and taping might be enough to hold them together, or twisting then hot gluing, or you can solder if you have the capabilities. Trust me, I had no experience with soldering other than purchasing the seven dollar iron, and it was pretty easy.

    After everything is dry and cool, wrap the two wires in tape, making sure not to cross the streams.

    Finally, wrap the whole thing in tape, and your mic is complete! Plug the cable into an amplifier and be amazed at the funny noises that come out.


    Stick it on an acoustic guitar with some blue goo, and you can play through an amp and get lots of cool feedback. Hold it up to your throat, add a little distortion, and you’ll wail like a badass banshee. Put it on anything at all, the possibilities are endless!


    The whole process was cheap and easy – for ten bucks you can get two piezo transducers and a sound cable, and there were about five minutes of labor involved. I soldered the wires (another ten bucks for an iron and solder), but you could just tape them if you want, and if you buy premade quarter inch sound cord you’ve cut out half the steps already. There’s basically no reason you’re not making a ton of racket yourself, just like your favorite rock stars!

    Thanks to Erinys, whose guide I used and simplified a bit. Thanks to you all for reading and rocking.

    Steve Schaberg, 2006