Most homebrew percussion gear ends up hidden inside a case or committed to a PCB, but this one lives proudly on solderless breadboards, and that is a big part of the charm. Waiting For Zyo has built an FM drum machine with an internal sequencer on a Raspberry Pi Pico 2, and the sounds coming out of that tangle of wires are remarkably big.
There are six voices: kick, snare, hi-hat, tom, clap and a metallic one. Sound shaping runs deep, with six primary controls covering pitch, decay, modulation depth and ratio, plus feedback and a modulation attack, and a second bank of six handling balance, pitch envelope decay and range, tone decay, spread and gate. On top of that sit a Fine Tune Mode with a 2-pole resonant filter, envelopes and an LFO, and a resonator called Cavity with tone, drive and ducking, modelled on the Volca Drum resonator, described as a short filtered delay with drive plus ducking.
Note entry and editing borrow from the Game Boy Nanoloop, while the step layout follows a classic bass machine's sequencer, except that a single trigger note can be nudged up or down right on the grid. The sequencer stretches from 16 to 64 steps and adds swing, parameter locks and on-grid rolls. Twenty buttons drive the interface, with three knobs on a small green perfboard and cardboard faceplate strips with printed labels over the breadboard sections.
Three beats were made from scratch using only the internal sequencer and the parameters, then recorded into Ableton with some filtering and reverb, because the audio output is still basic at this stage. Debugging is ongoing, no schematic or code has appeared yet, and a video series plus a 3D printed enclosure with graphics are planned.
Project by Waiting For Zyo. Watch it on their YouTube channel: