Maddie Synths
Open-source DIY Eurorack modules I build and program — one tiny board, many personalities.
These are my open-source Eurorack experiments — small, cheap boards where the firmware is the module. Each card below is a single firmware build treated as its own module, much like the WGD Modular melon. Reflash the board and it becomes something completely different.
The MOD1 and MOD2 hardware are open designs by Hagiwo — see the original build guides for MOD1 and MOD2. All firmware lives in the maddie-synths repository.
Maddie MOD1
Hagiwo's open 4 HP, +12V CV/gate hardware design, built on an Arduino Nano. Three pots, a button, a PWM LED, and four freely assignable 0–5V jacks. Swap the firmware and the same board becomes an envelope, an LFO, a sequencer, a clock, or a chaos source.
Butterfly
Chaos · Modulation
A Lorenz-attractor chaos source for organic, non-repeating CV — chaotic, but never random.
Dual AD
Envelope
Two independent attack-decay envelopes with per-trigger random timing variation.
EG
Envelope
A three-output envelope generator with a self-patchable end-of-cycle out for LFO or clock duty.
Euclidean
Sequencer · Trigger
8- or 16-step Euclidean rhythm generator with adjustable hits and per-step probability.
LFO
LFO · Modulation
A simple but CV-rich LFO — modulate frequency, waveform, and level for chaotic motion.
Logic
Logic · Utility
A dual logic processor: AND/NAND, OR/NOR, XOR/XNOR, COMPARE, MAX/MIN, and FLIP-FLOP.
Random CV
Random · Sequencer
A looping random CV and trigger sequencer with selectable length and trigger probability.
Random Walk + Lag
Random · Modulation
An ultra-slow random walk with a lagged second output for ambient, crossfading textures.
Tap Tempo
Clock
A four-output tap-tempo master clock with multiplied and divided outputs.
Terrain LFO
LFO · Wavetable
A procedurally generated triple-wavetable LFO with probabilistic SloMo 'breaths'.
Trigger Burst
Trigger · Clock
Clock-syncable trigger bursts with selectable count, division, and an internal clock.
Maddie MOD2
Hagiwo's open 4 HP audio-rate hardware design — the sibling of MOD1, built on a Seeed XIAO RP2350. Two gate inputs, a CV input, three pots, and a 10-bit ~36.6 kHz PWM audio output. The firmware decides whether it's a drum voice, an oscillator, a sampler, or something stranger.
Braids
Oscillator · Macro-oscillator
A Mutable Instruments Braids macro-oscillator port — dozens of synthesis models in 4 HP.
Breakbeats
Sampler · Drums
A PCM break-beat player with CV-selectable slice points, variable speed, length, and loop mode.
Clap
Drums · Percussion
A TR-808-style digital hand-clap: gated noise bursts into a band-passed exponential tail.
Claves
Percussion · Voice
A tunable claves/woodblock voice with morphable sine↔triangle waveform and 1V/oct tracking.
Flux
Noise · Physical Modeling
Seven modes from tuned resonance to pure chaos — modal, Karplus, noise colors, Lorenz, and drone.
FM Drum
Drums · FM
A two-operator FM percussion voice — six parameters across two modes with smooth pickup switching.
HiHat
Drums · Percussion
A white/blue-noise hi-hat with adjustable decay, decay curve, and band-pass frequency.
Kick
Drums · Percussion
A sine-based kick drum with six parameters and soft-clip drive, switchable via the button.
MOD303
Bass · Sequencer
An 'acid' 303-ish bass voice with a built-in Turing-style generative sequencer.
Radio Sampler
Sampler
A long-form sampler for vocals and speech — up to ~130s with variable speed and direction.
Sample Player
Sampler · Drums
A one-shot PCM sample player — up to 18 samples in flash, selected via two-stage CV.
Spiral 4Ever
Oscillator · Experimental
Auditory illusions and impossible sounds — Shepard tones, Risset rhythms, and tritone paradoxes.
Square VCO
Oscillator
A V/oct square-wave oscillator with vibrato LFO and chiptune-style octave toggling.
Tides
Oscillator · Function Generator
A Mutable Instruments Tides port — a tidal wavetable generator and function source in one.
VCO
Oscillator
A six-waveform oscillator with PolyBLEP anti-aliasing and negative-slope 1V/oct CV.