Musician-slash-programmer Elias Jarzombek has put together a synth with a difference: the Abacusynth is designed to be operated in much the same way as an abacus, yet spits out sounds rather than numbers.
"Abacusynth is a synthesizer inspired by an abacus, the ancient counting tool used all around the world," Jarzombek explains of his wooden creation. "Just like an abacus is used to learn the fundamentals of math, the Abacusynth can be used to explore the building blocks of audio synthesis. It exists in two forms, one digital and one physical, that are both based on the same primary interaction: placing and manipulating shapes on rods."
Externally, the machine looks like something you might get if you crossed an abacus with an arcade cabinet with a rotisserie grill and made the whole thing out of wood. Its curved pillars hold four horizontal rods, onto which triangular blocks have been placed. The console to the bottom includes LEDs, a speaker grille, and a knob.
The heart of the concept was inspired by a dissertation [PDF] written by Kate Compton in which the term "Casual Creator" was defined as a class of systems supporting creativity for creativity's sake. "I used the principles laid out in Compton's research to guide my design and development," Jarzombek explains. "Interpreting the Casual Creator ideas into the physical form meant building a stand-alone device with a built-in speaker. When you turn it on, it starts making sound so that you can immediately interact with it. As you explore the possibility space, you discover new sounds through your actions."
The Abacusynth, the physical incarnation of which follows an earlier browser-based software experiment, is powered by an Electrosmith Daisy Seed microcontroller, which funded on Kickstarter back in 2020 as a microcontroller development board designed specifically for embedded musical projects. The triangular spinners located on each rod are mechanical — they're actually shells for off-the-shelf fidget spinners — while the position on the rod and the speed of a spinner's rotation is measured using infrared sensors in the pillar sections.
A knob at the end of each bar hides a rotary encoder, attached to the same PCB as the distance sensor hardware, while a panel at the rear of the device offers a MIDI input socket, a line-level output for external recording or amplification, and power input.
"Moving forward," Jarzombek muses, "I am thinking a lot about modularity. I designed the inner section to be removable (so it doesn't have any electronics in it). Theoretically this could be swapped out for another more experimental design (maybe featuring one or two bigger spinners). Additionally, the core concept could be reduced to individual modules that could be stacked or linked together in some way."
More details on the project are available on Jarzombek's website; he has also released a version of the Abacusynth which operates as a software plugin for Ableton, and the original web-based version for in-browser experimentation.