Three Axis Midi Guitar

Watch the demo

This video goes over the build process & hardware, shows how the instrument is used, and shows off a Max patch demoing how the guitar can control various effects.

What is it?

This device is a custom midi expression controller that uses a track pad from a recycled laptop. The track pad has pressure sensing ability thanks to a force sensing resistor mounted underneath. This give us our 3 axes: up + down, left + right, and pressure. These inputs are converted to midi by the onboard Arduino Micro and can be used to control effects in real time through a daw or Max/MSP.

The test bed for all this is my very cheap white Squier Mustang. In addition to the custom midi controller, the guitar has been modified to output stereo, splitting the pickups between left and right with the flip of a switch.

Control Groups:

The toggle buttons above the strings correspond to 4 groups of 4 midi channels each. Each group contains the 3 axes as well as that switch's state.

This provides a framework for mapping midi channels to effects. In my demo I used the first channel group to control pickup switching and phase, and the other three on various effect parameters. Since this is just a midi controller at the end of the day, mapping can be as basic or as complex as needed.

Recent updates

I've made a number of updates to the instrument hardware recently including new plastics, some paintwork, and a more secure trackpad mounting solution.

A Learning Experience

I am frankly amazed and humbled that my home-built senior project has been so well received. I set the goal of building this before I really knew how I would do it, which forced me to learn new skills like cutting acrylic and doing some tight soldering.

Looking Forward

Receiving a Guthman nomination has given me renewed interest in this concept, and I'd like to refine it into something with wider application. I am currently exploring ways to implement this type of device in smaller and easier to use form factors.

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