Meebleeps Mutant

Generative Analog Synth Voice

Meebleeps / Wirehead Mutant Mozzi Synth
Meebleeps was my personal project and was rebranded as Wirehead Instruments in 2023 to avoid brand confusion with MeeBlip - another completely separate synth design company.
My first Arduino project started with the plan to push lfo/envelope voltages to my Volca Modular, but thanks to inspiration from Hagiwo and the Mozzi Library it turned into a cool little generative synth that I can let run all day, built to sync & fit with my Volca collection.

Source released under Creative Commons ttribution-NonCommercial-ShareAlike 4.0

Important build-note: my builds have used normally-closed switches, so the code assumes this. A couple of people building this have had issues because they have normally-open switches, so to adjust for this edit the code in updateButtonControls() to invert the results of each call to digitalRead().

Synth Voice Features
2 saw oscillators
Multiple tuning modes for 2nd oscillator - off, detune, fifths & octaves up/down
Digital low pass filter with variable cutoff and resonance
Variable level ducking/sidechain effect
Sequencer
Generative sequencer mutates/evolves at user-defined rate
Variable sequence mutation probability & note-density
Variable sequencer length (1-16 steps)
Sync input & output (Korg Volca compatible)
Selectable tonic note
Selectable scale quantisation (Major, Minor, Pentatonic, Phrygian (GOA!), Octaves, Fifths)
16-step parameter-lock recording of synth parameters (the Elektron way!)
Retrig (clone) button for fills
Tap-tempo control
Hardware
Arduino Nano (Elegoo)
Simple Mozzi output circuit
CV inputs (volca modular levels) for synth and sequencer parameters
Designed to fit into Volca form factor
Laser-cut metalisized acrylic faceplate
Laser-cut wooden box
9V DC Power input
Access to nano's USB port for firmware upgrades
Controls
Button Controls
Button Index Pin Name Function Alternative Function
0 D4 Func Access alternative control function n/a
1 D5 Start Starts/stops the sequencer Tap-tempo
2 D6 Scales Cycle through available musical scales Cycle through available mutation algorithms
3 D3 Root Increase the tonic note Decrease the tonic note
4 D10 Rec Hold to record knob movements Hold while moving a knob to clear the recorded value
5 D12 Clone Retrigger the current step
Analog Controls
Input Index Pin Name Function Alternative Function
0 A0 Species Oscillator 2 detune Amount of sidechain/ducking effect
1 A1 Lifespan Note length n/a
2 A2 Mutation Probabilty that sequence will change over time Probability of a note playing on any step
3 A3 Shape Shape of the filter envelope n/a
4 A4 Colour Base filter value Filter resonance
5 A5 Population Number of steps in the sequence 1-16 n/a
Problems (mostly hardware due to this being my first project!)
some sort of overflow bug linked to the low pass filter which causes the unit to enter a distorted output state until the cutoff is set to zero
no voltage protection on inputs
no buffering of inputs or outputs
no volume control
probably more unknown unknowns 😂

https://github.com/Meebleeps/MeeBleeps-Mutant-Synth