Quick start
- Choose a tempo, scene length and seed.
- Press Generate all to create rhythm, melody and bass.
- Press Play current.
- Open the three engines to edit the generated material, or use the mixer and effects to shape it.
- Capture good ideas, then export MIDI from Arrangement & MIDI.
Errant keeps rhythm, melody and bass as independent loops. Different loop lengths create slowly changing composite patterns.
Performance controls
Numbered boxes in each engine header preserve every generated version. Click one to recall it. During current-loop playback the change is queued and enters only when that instrument reaches its own loop boundary. Drag the numbered strip horizontally to browse a long history.
Tempo sets playback and exported MIDI tempo. Scene length sets the duration used by Capture All and combined scene export. Seed makes generated results repeatable. Global weirdness increases mutation and instability across generators. Master level changes internal audio only.
Play current follows the live pattern state, including edits made while playing. Play capture auditions the captured arrangement. Stop clears active playback and external notes.
Rhythm engine
The rhythm generator builds a four-lane Euclidean skeleton: Kick, Snare, Hat and Circuit. Loop length may be 1-16 bars. Kick downbeats remain present while additional kick placements change with each generated version. Click or drag across the grid to draw and erase steps.
Live modifiers
- Density adds or removes secondary events while preserving protected kick downbeats.
- Displacement moves eligible events away from their original steps.
- Ratchets create real repeated MIDI notes within a step.
- Swing offsets alternating subdivisions during playback and export.
Each modifier has its own On button. With all modifiers off, playback matches the visible base pattern exactly.
Melody engine
Melody begins with a 1-16-note identity, selected scale and one optional destabilising interval. Each return can reconstruct the identity differently according to Memory Error and tuning drift.
Audio control-data analysis accepts any audio file. It extracts a simplified contour and onset pattern, then uses those measurements to influence generated notes. It is not literal audio-to-MIDI transcription.
The internal melody instrument has ten patches, an ADSR envelope and optional chorus.
Bass engine
Bass has its own 1-16-bar loop, register, patch, ADSR and editable piano roll. Relationship modes can lock to the kick, avoid the kick, follow the melody or operate as an independent Euclidean circuit.
Piano-roll editing
- Click an empty cell to draw a note.
- Drag a note vertically to transpose it.
- Command-drag on macOS or Ctrl-drag on Windows/Linux to edit velocity.
- Option-drag on macOS or Alt-drag elsewhere to edit cents offset.
- Click an existing note without dragging, or right-click it, to erase it.
Velocity is shown by the fill height inside the note and by a live numerical readout during editing.
Mixer and effects
Each channel strip has internal level, dual left/right pan, mute, solo, delay send and reverb send. Level, pan and sends affect Errant's internal audio only. Mute and solo gate both internal sound and external MIDI.
The global delay offers straight, dotted and triplet values from 1/1 to 1/16, feedback, return, filtering, spread and ping-pong. Reverb types include Plate, Room, Hall, Ambience and Nonlinear, with size, decay, pre-delay, diffusion and tone controls. Effects may run in parallel or serial order.
Meta modulator
The X/Y pad and Z slider control three assignable parameters at once. Random assign chooses three different performance-safe targets. Rebase treats current target values as the centre position. Centre axes returns all axes to 50%.
Activate assigned modules is on by default. It automatically turns on a rhythm modifier or effect when that target is assigned, preventing apparently inactive modulation. Turn it off when you want assignment without changing module states.
MIDI routing
Press Enable MIDI and grant browser permission. Each instrument can play its internal sound, any number of checked external ports, or both concurrently. This includes enabled macOS IAC buses.
Web MIDI normally requires a secure context. Use the included Mac launcher, keep its Terminal window open, then use the localhost page it opens. External level and pan are deliberately not controlled by Errant's internal mixer.
Capture and MIDI export
Capture Rhythm, Melody or Bass appends that instrument's current native loop to its capture lane. Capture All records the evolving relationship of all three loops for the selected scene length. Captured clips remain unchanged while new versions are generated.
MIDI export is available for individual loops, the current combined scene and the complete captured arrangement. Ratchets are exported as separate notes. Microtonal notes use pitch bend and pitch-bend-range RPN messages.
Scales, tuning and microtonality
Scale families include Major and its modes, Melodic Minor and its modes, Harmonic Minor and its modes, and exotic or symmetrical scales. Tuning is independent of scale and includes Equal Temperament, 19-, 22-, 24-, 31- and 53-TET, Just Intonation, Pythagorean, custom cents and Scala import.
Mono Bend is best for monophonic destinations. MPE-style mode allocates overlapping microtonal notes across channels, provided the receiving instrument is configured compatibly.
Troubleshooting
No external MIDI ports
Use the Mac launcher and a Chromium-based browser, press Enable MIDI and approve permission. Confirm the IAC Driver is online in Audio MIDI Setup.
Meta modulation moves but is not audible
Keep Activate assigned modules enabled, or manually turn on the relevant rhythm modifier, delay, reverb or chorus.
High memory use
Stop playback, reduce long reverb decay and feedback, and reload the page if the browser heap continues growing. The Memory badge is only available in browsers that expose heap statistics.
Microtonal MIDI sounds out of tune
Set the destination's pitch-bend range to match Errant, or use a destination that responds to the exported RPN setup. Use MPE mode for overlapping independently tuned notes.