Stepper Synth Makes Surprisingly Pleasant Sounds

If you’ve ever been around a 3D printer, you have probably noticed that they make some strange sounds. Those sounds come mostly from the stepper motors that are used to move each of the axes. Unlike typical DC motors, stepper motors are designed to rotate in steps of just a couple degrees. When they need to rotate further than that the speed of the steps increases and ends up producing a pitch. By controlling the rotation speed, you can control the pitch. David Scholten’s Stepper Synth is a MIDI box that takes advantage of that stepper motor noise to make music.

We’ve seen many projects that convert 3D printers into musical instruments, but this is the first time we’ve seen a device that is purpose-built for making music with stepper motors. The device is a relatively compact box that contains four stepper motors. Because there are four individual stepper motors, the device is capable of four independent “voices.” Each stepper motor can be set to a unique pitch and that achieves in polyphonic sound. When connected to a computer, it can either play pre-written MIDI files or notes in real time via a virtual MIDI keyboard (or a real MIDI keyboard connected to the computer).

The Stepper Synth is controlled by an Arduino Uno board. It connects to the stepper motors through a CNC V3 shield, which has four DRV8825 stepper motor drivers. All of that is housed within an attractive 3D-printed enclosure. When connected to a Windows PC through the serial port, the Arduino Uno can be setup as a MIDI device using loopMIDI, Hairless MIDI, and MIDIMapper. You can use VMPK if you want a virtual MIDI keyboard for control. As you can hear in the video of the Stepper Synth playing the Final Fantasy VII battle theme, the resulting sound is really impressive.