Though manufacturers like Roland have been selling digitally-driven accordions for a number of years, they're not exactly wallet-friendly. Accordionist, composer and software developer Brendan Vavra opted to take the DIY route, transforming a relatively cheap, non-working acoustic instrument he bought on eBay into a capable MIDI music maker.
Vavra bought an acoustic accordion on eBay for US$150, which was in good working order but the reeds "were completely shot," making it unusable without repair. This wasn't something that concerned Vavra too much, though, as it was bought to be sacrificed at the alter of digital music.
He began by breaking apart the left hand Stradella bass system, removing and cleaning each of the 120 buttons – which were shaped differently under the business end, meaning that he had to keep track of each button's location for reassembly once the electronics had been installed.
The buttons in the accordion actually led to just 12 bass key pads and 12 chord key pads, so Vavra only needed to digitally map 24 pads to have all 120 buttons work in MIDI. Button movements were detected and converted to digital signals with the help of photo interrupters, which were blocked and unblocked when buttons were pushed.
A similar process was undertaken for the 41 keys of the instrument's right hand 19.25-inch keyboard, and the circuits and sensors were connected to an Arduino Mega processing heart powered by USB. The last additions to make it into the build were a Bluetooth transceiver to allow for untethered connection to a computer running music production software and a barometric pressure sensor used to pump up the volume and cook in some dynamic expression using the accordion bellows.
Vavra reports that the total cost of the conversion was in the region of $400, not including tools and solder. Though not as capable as Roland's V-Accordions, or more modern takes on the form factor, we think the DIY MIDI accordion looks the business and performs pretty well. You can judge for yourself in the video demo below, and if you're suitably inspired to build your own, Vavra has overviewed the project on GitHub (see source link).
Source: Brendan Vavra