Modulr Acid
A bass line in a box: sixteen steps, one oscillator, and a filter that sings when you ask it to.
Modulr Acid is a bass-line synthesizer with its own sixteen-step sequencer, after a sequencer of 1981. One oscillator, saw or square. A resonant low-pass with env mod, decay and accent. Pitch, accent and slide on every step. It runs from your host’s transport or on its own, and twelve patches load the sound and the line together.
Twelve patches, played as they ship.
Each clip is the plug-in itself: the patch is picked in the drawer and loaded, the pattern runs, and the cutoff is swept over the take. The sound is the instrument’s own output, with no effects and no mastering.
A line you load, then play with.
- Patches that load the whole line.Pick a patch and its tone and its sixteen steps arrive together; the drawer closes and the pattern is ready to run.
- Hold to preview.Hold a key to hear a patch’s tone on your own MIDI, then let go and the instrument is exactly as it was.
- Sync or run free.The pattern follows your host’s transport, or runs on its own clock. One key stops it, and it stays stopped.
- Edit the line by hand.Pitch keys, octave up and down, accent and slide on any step, a tap tempo, and a record arm that steps on as you play.
- Services.Choose whether the instrument answers your host’s MIDI and clock, set its output level, and age it: the decay shortens, the tuning drifts flat and the resonance rings less.
What it needs.
| Format | Systems | Licence |
|---|---|---|
| VST3 · Audio Unit | macOS 11 or later, on Apple silicon | A licence is needed to make sound. Without one the editor opens and the output is silent. |
The editor, and the module it becomes.
The plug-in is built. The Eurorack module is drawn, with its macro knobs and the control jacks under them, and is not.
The editor is the plug-in’s own, as it opens. The module is drawn by the specification’s own kit, and its values are illustrative, not measured. The design is TB-303’s grammar, redrawn in Modulr’s own words, and nothing on it is measured against the instrument.
TB-303, 1981.
The instrument’s own grammar, as the catalogue recalls it: the sections, the controls and the look the study borrows.
The bass-line grammar: one oscillator with a saw or square switch, a resonant low-pass with env mod, decay and accent, a volume, and a 16-step pattern entered with pitch keys, up, down, accent and slide.
A silver bass-line box in 18 HP: a silver frame round a graphite plate that holds the wave switch and seven black knobs, each with a CV jack, a row of sixteen step LEDs with one lit red, an orange stripe, and the jacks in a dark tray.
- A waveform switch (saw or square)
- Five knobs: cutoff, resonance, env mod, decay and accent
- Tuning and volume
- A sequencer with 16 steps, entered with note keys, octave, accent and slide
- Time-mode, tap, run and clear
- A tempo knob
- A small LED
- A pattern selector
The module, knob by knob.
The module is a design study and is not built. Its macros are the signature controls a player reaches for, not a generic set; each one has a control jack under it.
| Macro | Key | Range | Default |
|---|---|---|---|
| Tune | osc.tune | ±100 ct | 0 ct |
| Cutoff | vcf.cut | 20 Hz – 20 kHz | 20 kHz |
| Reso | vcf.res | 0–100% | 0% |
| Env mod | vcf.env | 0–100% | 0% |
| Decay | env.decay | 30 ms – 2.5 s | 200 ms |
| Accent | vca.accent | 0–100% | 50% |
| Volume | out.vol | -inf – +6 dB | 0.0 dB |
| Side | Jacks |
|---|---|
| In | Note (MIDI), V/Oct (CV), Gate (CV), Clock (CV) |
| Out | Out (Audio), Acc (CV) |
Legendary is the catalogue of the Modulr Synths project: 43 design studies drawn with the specification’s own kit, 33 after the synthesizers of all time and 10 after the drum machines. The makers and years named here are the instrument’s; the names, the layouts and every value are Modulr’s own.