Shapes
Documentation
Free polyphonic macro oscillator for VCV Rack 2. Last updated 14 October 2026.
Free module · 16 HP · early beta
A polyphonic macro oscillator
Shapes is one oscillator with 27 personalities: classic analog shapes, FM, formants, chords, speech, swarms, noise, physical strings and drums, and three bass engines of our own. It plays up to eight voices, and every note snaps to the scale you choose.
Twenty-four models come from the open-source engine of Plaits by Emilie Gillet, released under the MIT license. The quantizer, the voice handling, the display and the three bass engines (BASS M, BASS DETROIT, BASS DUB) are ours. Shapes is free.
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Controls
| Control | Range | What it does |
|---|---|---|
| MODEL | 1–27 | Chooses the model. The display shows its name and what the three main knobs do. |
| FREQ | ±4 octaves | Pitch around C4. With a scale selected, it snaps to the scale. |
| HARMONICS, TIMBRE, MORPH | 0–100 % | The three sound parameters. Their meaning changes with the model (see the table below); while you turn one, the display shows its name for this model, for example INVERSION 48 %. |
| ± FM | ±100 % | Amount of the FM input. Without a cable and with TRIG patched, the internal envelope bends the pitch. |
| ± TIMBRE, ± MORPH | ±100 % | With a CV cable: amount and polarity of the CV. Without a cable and with TRIG patched: amount of the internal envelope. |
| SCALE | 16 settings | Off (free pitch), chromatic, major, minor, the church modes, harmonic and melodic minor, major and minor pentatonic, blues, fifths, octaves. |
| ROOT | C … B | Root of the scale. |
| DECAY | 0–100 % | Decay of the internal envelope (low-pass gate) when TRIG is patched. |
| COLOUR | 0–100 % | Low-pass gate from VCA (left) to VCF (right). For the bass engines: how far the envelope opens the filter. |
| PRESET | 12 presets | Starting points: Dub Chord, String Pad, Dub Bass, VCF Stab, FM Bell, Pluck, Glass, Bass M, Swarm, Terrain, Kick, Detroit Bass. |
Double-click a knob to reset it.
The 27 models
Models 1–24 come from Plaits; 25–27 are Thoow's own bass engines. Models marked "needs TRIG" only sound when they are struck by a trigger (drums and resonators).
| Model | HARMONICS | TIMBRE | MORPH | Notes |
|---|---|---|---|---|
| 01 VIRTUAL ANALOG | DETUNE | SQUARE | SAW | Plaits |
| 02 WAVESHAPER | SHAPER | FOLD | ASYMMETRY | Plaits |
| 03 2-OP FM | RATIO | INDEX | FEEDBACK | Plaits |
| 04 FORMANT | RATIO | FORMANT | WIDTH | Plaits |
| 05 ADDITIVE | BUMPS | PEAK | SHAPE | Plaits |
| 06 WAVETABLE | BANK | ROW | COLUMN | Plaits |
| 07 CHORDS | CHORD | INVERSION | WAVE | Plaits |
| 08 SPEECH | MODE | SPECIES | PHONEME | Plaits |
| 09 SWARM | SPREAD | DENSITY | DURATION | Plaits |
| 10 NOISE | RESONANCE | CLOCK | FILTER | Plaits |
| 11 PARTICLES | SCATTER | DENSITY | FILTER | Plaits |
| 12 STRING | MATERIAL | BRIGHTNESS | DECAY | needs TRIG · Plaits |
| 13 MODAL | MATERIAL | BRIGHTNESS | DECAY | needs TRIG · Plaits |
| 14 BASS DRUM | PUNCH | TONE | DECAY | needs TRIG · Plaits |
| 15 SNARE | SNAP | TONE | DECAY | needs TRIG · Plaits |
| 16 HI-HAT | METAL | TONE | DECAY | needs TRIG · Plaits |
| 17 ANALOG VCF | RESONANCE | CUTOFF | WAVE | Plaits |
| 18 PHASE DIST | RATIO | AMOUNT | PULSE | Plaits |
| 19 6-OP FM A | PATCH | BRIGHTNESS | ENVELOPE | Plaits |
| 20 6-OP FM B | PATCH | BRIGHTNESS | ENVELOPE | Plaits |
| 21 6-OP FM C | PATCH | BRIGHTNESS | ENVELOPE | Plaits |
| 22 WAVE TERRAIN | TERRAIN | RADIUS | OFFSET | Plaits |
| 23 STRING MACHINE | CHORD | FILTER | WAVE | Plaits |
| 24 CHIPTUNE | CHORD | ARPEGGIO | SHAPE | Plaits |
| 25 BASS M | WAVE | CUTOFF | RESONANCE | Thoow |
| 26 BASS DETROIT | PULSE | CUTOFF | PUNCH | Thoow |
| 27 BASS DUB | WAVE | CUTOFF | WARMTH | Thoow |
The bass engines: BASS M is a warm analog-style bass with a 24 dB ladder filter, drive and resonance up to self-oscillation. BASS DETROIT is a bright pulse bass with PWM, a 12 dB filter and a punchy click on every strike. BASS DUB is round and dark: sine to triangle with a sub, a low ladder filter and a little warmth and drift. With TRIG they play notes with an envelope; without TRIG they drone. AUX outputs the raw oscillator before the filter.
Quantizer
Plaits itself has no scale quantizer; Shapes adds one. FREQ and the V/OCT input are added first, then every voice snaps to the nearest note of the scale above ROOT. A small hysteresis keeps a note from flickering when the input sits exactly between two scale notes. FM is not quantized, so vibrato and pitch envelopes stay smooth. Set SCALE to Off for free pitch.
Voices and triggers
Shapes is polyphonic: the widest polyphonic cable at any input sets the number of voices, up to eight. Each voice has its own pitch, trigger and envelope; a mono cable at an input applies to all voices. OUT and AUX are polyphonic.
With a cable at TRIG, every trigger strikes the internal envelope (low-pass gate, DECAY and COLOUR) and excites drums and resonators. Without TRIG, the models play continuously; LEVEL then opens the gate like a VCA. Glide (context menu) slides each voice to its new pitch in 30, 100 or 300 ms.
Jacks
| Jack | Signal |
|---|---|
| MODEL | ±5 V sweeps through all models. |
| HARMO, TIMBRE, MORPH | CV for the three sound parameters (TIMBRE and MORPH through their ± knobs). |
| FM | Pitch modulation, 1 V = 1 octave at full ± FM. |
| V/OCT | Pitch, 1 V/oct, polyphonic. |
| TRIG | Trigger or gate, polyphonic: strikes the envelope. |
| LEVEL | 0–8 V: opens the low-pass gate, sets the strength of the strike. |
| OUT, AUX | Main and auxiliary sound, polyphonic, ±5 V. AUX is a variant whose character depends on the model. |
Display and menu
The display shows the model with its number, the scale and root, a scope of the first voice, and below it what HARMONICS, TIMBRE and MORPH mean for this model. With more than one voice it shows the voice count, otherwise the note that is playing.
Menu: Glide (off, 30, 100, 300 ms) and Show values on display.
Changelog
Beta 1 · 2.0.1
- First public beta: 24 Plaits models, three bass engines, scale quantizer, up to eight voices, glide.
The number after "Beta" counts our releases; the plugin itself reports a version starting with 2, because VCV Rack 2 only loads plugins whose version starts with its own major number.
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Credits and license
Models 1–24 use the sound engines of Plaits by Emilie Gillet (Mutable Instruments), under the MIT license; the license text ships with the plugin. "Plaits" and "Mutable Instruments" are names of their owner and are used here only to credit the source. Quantizer, voices, bass engines, panel and display by thoow, Hamburg.
Questions or feedback: service@thoow.com