guitar sensor

schematics for the optical guitar sensor

Background
In the work Cryptoguitar I set out to capture each moment my right hand plucked a guitar string. This is extremely difficult to do with a microphone as the strings produce long sustaining sounds that overlap each other meaning that the onset of each note is buried in sound. The most common way to solve this problem is to use a hexaphonic or divided pick up. This technique uses as separate pickup for each string. Companies such as Roland have a long history of developing these but generally they rely on detecting the strings through electromagnetic coils. As this technique only works with steel strings I investigated ways to do this with a nylon string guitar.

One approach to sensing the vibration of each string on a nylon strung guitar is to use a piezo-based system such those as developed by RMC. Unfortunately this involves some considerable modification to the instrument including drilling holes and changing the saddle slot. Therefore, I developed a way to do this based on infrared optical sensors. This method can create separate signals from each string. Whilst the sound quality is inferior to a piezo system it works sufficiently for note detection and can be used without permanent modification to a guitar. The system is in early development but below are some images and schematics of the circuit made in EAGLE.

cryptoguitar sensor

cryptoguitar sensor

download schematic for optical guitar sensor