Jazz Hands: Hybrid MIDI Saxophone
This augmented saxophone uses Hall effect sensors and an ESP32 board to play as an acoustic instrument or MIDI input.
With the availability of MIDI-compatible development boards, sensors, and electronics creation tools like KiCad, making your own MIDI controller has never been more accessible. This type of device can be a simple button on a breadboard, or in the case of the Jazz Hands hybrid saxophone by Andrew Chi, an array of individual sensors are applied to an actual instrument.
The heart of the device is an Arduino-compatible ESP32 Thing, which is, in turn, installed on a custom PCB. This PCB features a five-pin MIDI out connector, and accommodates the 20 on-sax key sensors, as well as an expression pedal via an audio-style TRS jack. Per the ESP32’s abilities, the Hybrid Sax can also perform MIDI out over BLE, and uses capacitive inputs for MIDI octave switching.
To electronically read the saxophone inputs, Hall effect sensors are embedded below each of the keys with Sugru putty, while neodymium magnets are attached to the keys themselves (also with Sugru). These sensors show whether the keys are open or closed, and are connected to the central ESP32 board using thin wires that snake all along the instrument. Because Sugru can be removed fairly easily, and the ESP32 board is attached with Velcro, the instrument can be restored to its original condition as needed.
Jazz Hands can be played in a dual acoustic/MIDI role and electronic breath control has been implemented, though the whole setup is a bit of a prototype/work-in-progress. It looks like a lot of fun, and something that could inspire other dual-use acoustic-electric devices. PCB files and code are available on GitHub.
