This post aims to look at ‘How to Make a Contact Microphone’
Whats Needed?
- Piezo Transducer (I purchased a couple from my local Maplin store which offered different sizes ranging from £1 – £3)
- 1/4 Audio Jack Lead
- Wire Cutters
- Soldering Iron
- Tape
- Blu-Tack
I purchased two Piezo Transducers and a 10ft Audio Cable to create two Contact Microphones, each with a 5ft lead.
Step 1
The first step is to cut the audio cable into two halves, each sized according to preference. Once cut you need to strip the cable (about an inch) to expose the wires.
When exposed you should see a center wire surrounded by many copper wires. Group and twist the copper wires and pull to one side. Then expose about an inch of the center wire.
Pictures Below…
Now that you have an audio cable with two wires exposed, it is time to connect the Piezo Transducer.
Step 2
Connect the two wires on the Piezo Transducer to the exposed wires on the audio cable, twisting them secure.
Once secured proceed to solder the wires in place.
Whilst soldering it became apparent that the solder was rolling off of the exposed center wire, making it difficult to fix in place. Once soldered I check the lead in an amplifier to test the connections.
Step 3
Now that the audio cable is soldered to the Piezo Transducer it is a good idea to try and further protect the connection. I simply taped around each connection separately and then taped them together.
If you have access to a glue gun, the connection protection possibilities are endless.
I found some solid looking designs here: Feisty Little One
Step 4
Using the Microphone…
I first began by attaching the contact microphone to different guitars and in different positions using Blu-Tak. Depending on the instrument there is no right or wrong place to attach the contact microphone just experiment to see what sounds good.
However, when experimenting it became apparent that avoiding excessive low frequencies is a must when using an amp (unless you are aiming for feedback). As soon as the low frequencies coming from the amp start to resonate the guitar it can be difficult to control.
Also ensuring that the contact microphone is flat against the instrument helps avoid feedback issues.
As shown above the contact microphone is coming away from the guitars body. In this position the microphone captured more low frequencies and therefore caused feedback. Depending on your lead size you could possibly experiment with this if you can get enough distance from your amp.
Using Blu-Tak also can be problematic as it sometimes isn’t strong enough to attach the contact microphone to a surface, however it is safe to put on guitars without damaging the finish. Blu-Tak was also positioned underneath the contact microphone to attach to the source. Although successful the initial attachment achieved more appealing results.
Being able to attach the contact microphone to endless surfaces without capturing unwanted sound makes them appealing in consideration to other microphones. Although the results on the acoustic guitar were not as ‘professional’ as when captured using a high end condenser microphone, there is definitely a lot of experimentation that could be made using contact microphones.
Attaching the contact microphone to an amplifier created feedback, that when controlled allowed the amplifier to be used almost like an instruments by hitting the amp. Using the built in effects, some appealing sounds were created that could be used for Sound Design.
Throughout university a friend of mine attached multiple contact microphones to the bottom of a board to record footsteps. Again, there are many possibilities. Some more ideas can be found at ExperimentalNetwork.org
I hope this guide has helped.
Please feel free to send me any examples from your Contact Mic projects.
PB
