This project was featured on Hackaday.

MIDISWAY is an effects unit that simulates the pitch variation found in old vinyl and tape. The effect is novel in that it is implemented directly via MIDI rather than audio post-processing. The on-board microcontroller directly modifies the pitchbend parameter of the target instrument via its MIDI in port by a sine wave, reproducing the subtle oscillation of an off-centre vinyl or eccentric tape spool.

The code was written from scratch in a couple of days. The unit itself was built using a collection of scrap components and a few stock parts in a day. The materials needed to build a MIDISWAY unit are as follows:

The STL files for the Enclosure and Cover can be downloaded from the following links:

MIDISWAY Enclosure.stl
MIDISWAY Cover.stl

The Arduino code can be downloaded from the following link:


The effect is intended to be most useful in a live performance scenario, where the incoporation of an audio wow effects unit is not trivial. The unit can simply be plugged into any MIDI instrument and the desired effect is produced and can be tweaked at will.

The piano phrases in the song Promises were processed using the unit live. The video below shows the build process and song recording session, and demonstrates how a few days of prototyping resulted in the production of a useable effects unit.

This video is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License