Eleven modules for VCV Rack 2.x by Javier Melgar (Animatek).
- UZZ — Ultimate Ztep Zequencer: a 16-step sequencer with per-row shift, probability, accumulator, and flexible clock.
- UZZ-X — 6HP CV expander for UZZ: bipolar offsets for steps, start, direction, ratio, swing, probability and accumulator, plus absolute step addressing, rotation triggers and a reverse gate.
- CAP — 6HP ducking VCA with sidechain envelope: stereo audio in/out, a VCA CV input for ordinary voltage control over gain, humanised per hit so the ducking breathes, and self-patchable into a jittered LFO.
- ONE — 6HP MIDI-to-CV interface designed for the Oxi One controller.
- MULTI — 10HP expander for ONE with 8 configurable multi-track outputs.
- APC40 CTRL — 13HP MIDI-to-CV bridge for the Akai APC40, with all knobs, faders and the master fader on a single panel.
- UNIT-D — deterministic polyphonic generative sequencer based on unit-distance graph walks. Manuals: EN / ES.
- BLANK 3 — 3HP blank panel with animated low-opacity Animatek logo pattern and global pause option.
- BLANK ACID — 3HP blank panel with animated acid smileys and a shared canvas between adjacent blanks.
- ATEK303 — TB-303 voice emulation with circuit, Open303 and custom sound models.
- ATEK303 SEQ — 16-step algorithmic acid pattern generator and ATEK303 expander.
| Modules | English | Español |
|---|---|---|
| UZZ + UZZ-X | Manual | Manual |
| ONE + MULTI | Manual | Manual |
| APC40 CTRL | Manual | Manual |
| CAP | Manual | Manual |
| UNIT-D | Manual | Manual |
| BLANK 3 + BLANK ACID | Manual | Manual |
| ATEK303 | Manual | Manual |
| ATEK303 SEQ | Manual | Manual |
UZZ is a step sequencer originally created as a Max for Live device, designed for immediate control, clear visual feedback, and fluid musical flow.
This repository is a port to VCV Rack 2.x, aiming to preserve the original philosophy: precise timing, structured improvisation, and modular flexibility.
- 16 steps with per-step Pitch, Octave, tempo-relative Duration, Mod1, Mod2, and bipolar Prob/Pulse
- Per-step step mode: Play, Mute, Skip, Accum Up, Accum Down, Pulse, Gated, Hold
- Active window: configurable Start and Step count with wrap-around
- Clock ratios: ÷8 to ×8 and beyond, with swing
- Direction modes: Forward, Backward, Pendulum, Ping-Pong, Random, Drunk, Odd/Even, Jump, Converge, Diverge
- Global glide (slew) on pitch output
- Accumulator: semitone offset that accumulates on ACCUM steps, with wrap control
- Per-row Randomize buttons with CV trig inputs (Pitch, Oct, Mode, Dur, Mod1, Mod2, Prob)
- Per-row Shift up/down arrows for all rows including Prob/Pulse
- Per-step Prob/Pulse knob: probability on the left side, pulse multiplier on the right side
- Global Probability knob — multiplicative on gate triggering
- Polyphonic step-gate output (one channel per active step)
- EOC output, transpose input, reset input
A 6HP MIDI-to-CV converter designed for the Oxi One sequencer/controller, covering all its output modes.
- V/Oct, Gate, Velocity outputs
- 8× CC outputs (configurable CC numbers per slot)
- Clock output and CLK/n divisions (÷1 to ÷32)
- Run output
- Supports Mono, Poly, Chord, Multitrack and Matriceal Oxi One modes
- Channel-selectable MIDI input (Omni or specific channel)
- Compact 6HP panel
A 10HP expander for ONE that unlocks its multi-track capabilities.
- 8 configurable tracks with independent V/Oct, Gate, and Velocity outputs
- Works alongside ONE in Multitrack and Matriceal modes
- Must be placed immediately to the right of ONE
- Mirrors the current ONE track configuration through the expander link
A 13HP MIDI-to-CV bridge that captures every continuous controller of the Akai APC40 MkI/MkII on a single panel. Designed to sit next to MULTI: title, header divider and the first knob share the same vertical position so both modules read as a pair.
- 8 Track Controls (T1–T8) on CC 48–55 with per-output attenuverters.
- 8 Device Knobs (D1–D8) on CC 16–23 with per-output attenuverters.
- CUE level (CC 47), MASTER fader (CC 14) and XFAD crossfader (CC 11), each with attenuverter.
- 8 Channel Faders (F1–F8) in a dedicated column on the right: all share CC 7 but on MIDI channels 1–8, so the eight faders of the APC40 reach Rack as eight independent CV outputs without remapping the controller.
- All knob/CC controls listen on MIDI channel 1; the fader column accepts channels 1–8 in parallel.
- 0 → 10 V output range. Use the per-control attenuverter to scale or invert as needed; faders pass through directly.
A 6HP trigger-fired ducking VCA. Feed it the same trigger that fires the kick, run the audio through it, and the signal drops and recovers on every hit — no compressor involved. The VCA is built in, so nothing else is needed, but ENV still carries the envelope as CV for whatever else you want to duck in step.
What separates it from any inverted envelope patched by hand is that each hit is slightly different from the last, so the ducking breathes like an analogue compressor instead of stamping an identical curve forever.
- RECOVERY (40 ms – 1 s, exponential), DEPTH (0–100 %) and JITTER (0–100 %) down the left, with the LEVEL slider filling the right.
- The slider is also the meter, and the number of bars follows what there is to show: one for a mono path, two as soon as both IN L and IN R are patched (whatever the polyphony — two mono cables are still two paths), and one per channel, up to 16, under per-channel envelopes. Each bar draws the gain applied to its channel, not the audio level: metering the signal would turn it into an output VU and the ducking would stop being legible. Brightness follows the envelope, so a duck reads twice — shorter and dimmer. Drawn in Rack's light layer with a soft bloom, so it stays lit when you dim the room brightness.
- Stereo audio path: patch IN L and IN R for true stereo, or just IN L — right is normalled to left, so one cable turns it into a mono-to-stereo ducker. Unity gain at rest.
- Humanisation across three dimensions per hit: recovery time (±50 %), depth (±25 %) and curve exponent (±30 %) at full jitter, scaled linearly by the knob. At JITTER = 0 the module is perfectly deterministic and repeatable.
- The variation is a correlated random walk, not white noise: each hit relates to the previous one, which is what makes it read as human rather than as random.
- By default every audio channel shares one envelope, so a stereo pair ducks symmetrically and the image does not wobble. Per-channel envelopes in the menu gives each channel its own generator instead — for ducking several unrelated tracks through one polyphonic cable.
- Fixed 2 ms fall and 12 ms hold at the floor, so retriggering mid-recovery never clicks or steps the level upward.
- ENV rests at 10 V and dips, following TRIG's channel count. Handy for ducking a reverb return or driving a filter in step with the audio path.
- EOC fires a 1 ms trigger when the recovery completes and the envelope is back at rest. A retrigger that cuts the recovery short fires nothing, so EOC always means "the duck has fully released" rather than turning into a copy of TRIG at fast tempos.
- VCA CV input for plain voltage control over gain: unipolar and linear, 0 V closes and 10 V passes the full ceiling, multiplying what the LEVEL slider sets rather than replacing it. Unpatched it attenuates nothing, so older patches are untouched. Patch an envelope into it and CAP is an ordinary VCA, with the trigger-fired ducking sitting on top when you want it. It does not touch ENV or EOC, but the meter follows it, since the meter shows the gain actually applied.
- Layout: RECOVERY · JITTER · DEPTH down the left with the meter-slider alongside them, ending level with the foot of the knob column. Below them the two CV jacks share a row, and neither carries a label: a hairline runs from each one up to the control it modulates — D-CV to the DEPTH knob directly above it, VCA to the fader — which says more than four letters of text would. The same hairline idiom ties the unlabelled manual trigger button to the TRIG jack on its right, since they do the same job. IN L · IN R close the block: everything that goes in sits above the divider. Below it, everything that comes out — ENV · EOC, then OUT L · OUT R.
- Self-patch EOC into TRIG and one press of the button sets it free-running: the cycle is 2 ms fall + 12 ms hold + recovery, so it oscillates from about 1 Hz to 18.5 Hz — a function generator whose every cycle differs, which a plain LFO cannot do.
- DEPTH CV input, summed with the knob (10 V = 100 %) and clamped.
- Context menu: recovery curve (exponential / linear / logarithmic), freeze jitter for A/B comparison, per-channel envelopes, level attenuates ENV (off by default, so ENV stays a full 0–10 V envelope unless you want the slider to double as a CV attenuator), and reset jitter seed.
A compact deterministic generative sequencer based on unit-distance graph walks. UNIT-D creates a seeded 2D cloud of nodes, connects nodes that sit near a target distance, and turns the graph traversal into quantized pitch, gates, accents and related X/Y modulation. The same seed and settings always produce the same structure, so it can move between generative exploration and repeatable musical phrases. Manuals: EN / ES.
- Seeded graph generation with 8–64 nodes, unit radius, tolerance fine-tuning and musical density control.
- Deterministic walker with selectable Walk mode, resettable state and repeatable behaviour for saved patches.
- Bipolar LOCK control for gradual 16 / 32-step phrase capture, including forward and reverse lock directions.
- Quantized minor-scale V/oct output with selectable 1–4 octave range.
- Tempo-following Gate output with gate length and gate-density controls.
- Related Accent, X CV and Y CV outputs derived from graph degree and node position.
- Polyphonic operation from the context menu: 1–8 voices, with shared seed or per-voice seed graphs.
- Inputs: Clock, Reset, Seed CV and Density CV.
- Outputs: V/oct, Gate, Accent, X CV and Y CV.
Two 3HP blank panels for filling small gaps in a Rack patch while keeping the Animatek visual language.
- Dark-only 3HP utility blanks with Animatek logos or acid smileys.
- Adjacent blanks form a shared animated canvas with configurable speed and colour.
- Context-menu Pause animation option.
(2026-05)
- Added UNIT-D, a compact deterministic polyphonic generative sequencer based on unit-distance graph walks.
- Seeded 2D nodes create graph transitions with controls for node count, radius, density, tolerance, walk mode, range, gate length, gate density and lock.
- Outputs include quantized V/O, GATE, ACC, X CV and Y CV for linked melody, gates, accents and modulation.
- Added expanded manuals in English and Spanish:
Manuals/UNIT-D_Manual_EN.mdandManuals/UNIT-D_Manual_ES.md.
- Added BLANK 3, a 3HP blank panel with Animatek branding.
- Background logos are generated per instance with randomized position, size, rotation and opacity.
- Logos drift with a very slow random walk by default.
- Added right-click Pause animation option, global across all BLANK 3 instances, to freeze animation and reduce idle work.
- Public display names changed from OXI-CV to ONE and from OXI-CV EXPANSOR to MULTI.
- Added bottom-panel module labels using the same blue label style as UZZ.
- Updated custom Animatek input/output port assets across the public modules.
(2026-05)
- 13HP MIDI-to-CV bridge for the Akai APC40 with the full continuous-controller surface on one panel: 8 track controls, 8 device knobs, Cue, Master and Crossfader (with attenuverters), plus a separate column of 8 channel faders that listen to CC 7 on MIDI channels 1–8 directly.
- Layout aligned with OXI-CV EXPANSOR so the two modules share title height, header divider position and first-knob row when placed side by side.
- Deleted
res/UZZ-overlay.svg/res/UZZ-overlay-light.svgand the unusedUzzStaticOverlaywidget. Older VCV versions could render the obsolete overlay on top of the current panel; the dead code path is now gone.
- New
BasicDisplaybase widget shared byParamDisplayandAccumDisplay— drops ~25 lines of duplicated background/font setup. - New
loadPluginSvgOr(plugin, fallback)helper used byRowShiftButtonandStepModeButtonto replace the hand-rolled load-with-fallback pattern. - The five identical 16-step
UzzArcKnobloops inUZZWidgetcollapsed into a singleaddArcKnobRow(y, paramBase)lambda. - Hardcoded display blue replaced with the existing
displayBlue()helper fromCommonWidgets. - Dead
UZZ_USE_CODE_LABELSmacro and its always-true branch removed.
(2026-04)
- Added Panel → Light / Dark submenu to the right-click context menu of UZZ, OXI-CV and OXI-CV EXPANSOR.
- Toggles VCV Rack's global
preferDarkPanelssetting directly from the module, so the theme can be switched without opening Rack's global preferences.
- The per-step Prob/Pulse knob now applies probability on its left side (negative values) for Pulse, Gated and Hold steps too — previously these modes only honoured the global probability.
- Right side of the knob keeps its meaning: pulse count, always at 100 % probability per repetition.
- Fixed a case where the Gate output could stay high for several seconds (or indefinitely) when the upstream clock was held at 10 V or had been connected long before play started.
- Internal clock now ignores the first edge's accumulated time and rejects implausibly long periods (>5 s ≈ 12 BPM) instead of feeding them into the gate-length calculation.
- Schmitt trigger uses explicit
0.1 V / 2 Vthresholds (matching Fundamental SEQ3) for cleaner edge detection on signals that idle slightly above 0 V. - Added hard upper bounds: gate length capped at 2 s, Gated sustain capped at 8 s — even with pathological state the gate cannot stay open indefinitely.
(2026-04)
Kept as a Rack 2.x-compatible
2.xrelease so VCV Rack 2 loads the plugin.
- Added three per-step modes: Pulse, Gated, and Hold.
- Pulse generates ratcheted sub-gates inside the clock period.
- Gated can stretch one step across multiple clock periods.
- Hold can re-fire the current step across multiple incoming clocks before advancing.
- Added dedicated panel icons for the new step modes.
- The former Probability row is now Prob/Pulse.
- Knob center (
0) means normal playback: 100 % probability / ×1 pulse. - Turning left sets per-step probability from 100 % down to 0 %.
- Turning right sets pulse multiplication from ×2 to ×8.
- Randomize, Shift and Reset for the row were updated to the new bipolar behavior.
- For Play and Accum steps, the row acts as probability.
- For Pulse, Gated, and Hold steps, the left side still acts as per-step probability and the right side as pulse count (always 100 %).
- Added Pendulum, Odd/Even, Jump, Converge, and Diverge direction modes.
- Ping-Pong now exists as its own mode, distinct from Pendulum.
- Jump uses a configurable stride from the right-click context menu.
- Sequencer state now stores the advanced direction position so patches resume consistently.
- The Duration row is now tempo-relative duty, displayed as percent of the clock step instead of independent seconds.
- Gate length calculation was centralized to keep pulses and gated playback consistent across ratios.
- In Gate mode, ratcheted repeats now use the repeat interval as their timing window so each repeat has a clear low gap before the next gate.
- Ratchet sub-pulses are scheduled inside the audio process loop rather than treated as separate steps.
- Hold/gated states are cleared cleanly on hard stop and reset.
- Group guide lines now sit between steps 4/5, 8/9, and 12/13.
- Group guide lines use the Animatek logo blue with reduced opacity.
- The row label for the bipolar probability/pulse controls is shown as PROB to fit the panel.
(2026-04)
- Added ACCUM WRAP Trimpot (0–12 st) alongside the existing ACCUM AMT knob.
- When WRAP > 0, the accumulated pitch offset loops via modulo: e.g. WRAP=6 cycles the offset 0→1→2→3→4→5→0→... (50 % of an octave).
- WRAP=12 gives a full-octave cycle; WRAP=0 (default) preserves the original ±12 semitone behaviour.
- Works symmetrically for ACCUM UP and ACCUM DOWN.
- The AccumDisplay panel widget shows both values: semitone amount (top line) and wrap point or "OFF" (bottom line).
- Existing patches are unaffected (WRAP defaults to 0 = OFF).
- Slug comparisons in
process()replaced with model-pointer comparisons (avoidsstd::stringallocation at audio rate). noteToVoct()helper added toplugin.hpp, removing 3 duplicated inline expressions across OXI-CV and OXI-CV EXPANSOR.silenceAllVoices()extracted in OXI-CV, replacing two copy-paste blocks.fillRow()helper added to UZZ, simplifying 7reset*Row()methods.- Dead code removed: unused lambdas and constants.
(2026-04)
- Added PROB row: 16 Trimpot knobs (0–100 %, default 100 %) placed above the Pitch row, one per step.
- Added Global PROB knob in the bottom panel (bottom-right position, replaces old EOC slot).
- Probability is multiplicative:
p_final = p_step × p_global. Only the gate is silenced on failure; pitch, Mod1/Mod2 and accumulator continue unaffected. - Probability is evaluated on every step arrival using
random::uniform(). - Full row support: Randomize PROB button + CV trig input, Shift PROB up/down arrows (10 % per click), right-click Reset PROB to 100 %.
- New params appended at end of enum — existing patches default PROB to 100 % and play back unmodified.
- STEP_GATES (poly) output moved to the step 11 column (bottom row).
- EOC output moved to the step 13 column (bottom row).
- Global PROB knob placed at step 15 column (bottom row) with PROB label at step 14.
- All panel labels now use
APP->window->uiFont(Rack's system UI proportional font) rendered indrawLayer(1), matching the look of OXI-CV. - Fake-bold via 0.15 px horizontal pass, uppercase enforced at construction.
- Row labels (MODE, PITCH, OCT, DUR, MOD1, MOD2, PROB) repositioned above their trig input ports with consistent 3 px gap.
- OXI-CV: 6HP MIDI-to-CV for Oxi One — V/Oct, Gate, Velocity, 8× CC, Clock, CLK divisions, Run. Mono/Poly/Chord/Multitrack/Matriceal modes.
- OXI-CV EXPANSOR: 10HP expander — 8 configurable tracks with V/Oct, Gate, Velocity outputs.
(2025-11)
- Fixed critical crash when reloading the Rack plugin inside Bitwig or other hosts.
dataToJson()now creates its ownjson_object()when the base isnullptr.dataFromJson()calls the base method before applying stored values.- UI asset safety during headless scans — constructors guard against null
APP->window.
- Default clock ratio set to ×1.
- Virtual clock rewrite: internal oscillator only runs when ratio ≠ ×1.
havePhaseforced off at ×1 to prevent extra steps during held gates.
- Font loading uses
asset::system("res/fonts/ShareTechMono-Regular.ttf")withAPP && APP->windowguards. - Text rendering tuned: centered alignment, pixel-rounded coordinates, 9 px size.
- Unified safe SVG loader routing all assets through a single helper.
- Step-mode icons and row-shift arrows render correctly after VST project reloads.
(2025-10-03)
- Added per-row shift controls for Pitch, Octave, Duration, Mod1, and Mod2.
- Contextual menu: submenus for Direction mode, Range Mod1/Mod2, EOC-on-reset toggle.
- Implemented optional EOC trigger on external reset with persistence.
- Refined reset handling: active step fires before jumping to start window.
- Custom input/output port widgets (10 % scale reduction).
- Tuned slew to logarithmic curve.
(2025-09-23)
- Clock multipliers now trigger the first sub-tick correctly.
- Limited maximum multiplier to ×48.
- Old patches with ×64/×96 clamp to ×48 automatically.
Build against the VCV Rack 2 SDK:
RACK_DIR=/path/to/Rack-SDK makeInstall the plugin into your local Rack setup:
RACK_DIR=/path/to/Rack-SDK make installCreate a distributable package:
RACK_DIR=/path/to/Rack-SDK make dist- Website: https://animatek.net
- Manual: https://animatek.net/ultimate-ztep-zequencer-vcvrack/
- YouTube: https://www.youtube.com/@animatek
- Author: Javier Melgar (Animatek)
- License: GPL-3.0-or-later