Awesome
Meebleeps Mutant Mozzi Synth
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.
https://www.youtube.com/watch?v=d2Lml1Z9uWc
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 😂
Thanks
- Inspired by Hagiwo's modular builds: https://www.youtube.com/channel/UCxEr...
- Mozzi audio library: https://sensorium.github.io/Mozzi/
- Inkscape for vector graphics: https://inkscape.org/
- Fritzing for circuit design: https://fritzing.org/
- Great Scott for awesome electronics tips! https://www.youtube.com/channel/UC6mI...