This page outlines the step by step process for building your own contact microphone. Let’s begin. First you will need an audio cable. I used an unbalanced 1/4” cable, shown below.
Notice I have stripped one half of the cable. This is done so we can later connect the exposed wires to a piezo transducer (shown below). Also notice the primary wire mesh has been twisted into a more solid thread.
This piezo element is encased in a plastic shell. The shell will need to be removed in order to extract the metal disc from within.
This transducer was purchased at an electronics shop, but I recommend looking online for those that are without the casing and, therefore, much less expensive.
We are now ready to connect the transducer to the audio cable.
The “mesh thread” is twisted with the wire that has come pre-soldered directly to the metallic portion of the disc, along the outer edge (in this case, the black wire). The wire within the inner tubing of the audio cable is twisted with the wire leading to the white, central pad of the piezo element (red wire).
A little solder for good measure.
I simply wrapped the wires and disc up with electrical tape, giving the finished product a distinctly “homemade” look. But, heat shrink tubing will lend a much more professional visual aesthetic to your mic. This is done to protect the disc and the wire connections.
I use my contact mic for triggering audio in max/MSP by taping it to a practice pad and drumming as I wish while max interpret the spikes in the audio as “note on” messages for a randomized synthesizer (likewise built in max).
Below is a short video demonstrating the functionality of a DIY contact mic being used to trigger a sample via Max for Live.
DISCLAIMER: You will notice that, in this demonstration, I am playing directly on the contact mic. THIS IS NOT RECOMMENDED. I did this to demonstrate the sensitivity of the piezzo element. Direct contact with the element can be damaging if done with enough force.
You can download this device as well as our highly coveted cowbell sample by clicking here.
Duane