SlicBeat Documentation

Getting Started

SlicBeat is a tracker-style music production app for iOS. If you've used trackers like LSDJ, Renoise, M8, or the Polyend Tracker, you'll feel right at home. If you're new to trackers, here's the key concept: music is composed on a vertical grid where notes scroll downward, step by step.

Creating Your First Project

When you launch SlicBeat, it automatically loads your last project. To create a new one, tap the folder icon in the transport bar to open the Project browser, then tap + to create a new project.

Adding an Instrument

Tap the waveform icon in the transport bar to open the Instruments panel. Tap + to add an instrument. You can choose from:

• Default Samples — Browse the bundled sample library
• Browse Files — Import your own audio files (WAV, AIF, MP3, M4A, CAF)
• Looms Synth — Create a synthesizer using one of 21 Plaits engines
• Acid Synth — Create an SB-303 acid bass synth
• MIDI Instrument — Route to an external MIDI device
• Load Preset — Load a previously saved instrument preset

Writing Your First Pattern

The main tracker grid shows one clip at a time. Each clip has 16 steps. Tap a cell to open the step editor, where you can set the note, instrument, volume, and up to 3 effect commands. Place notes on different steps to create a rhythmic pattern, then press play to hear it loop.

Interface Overview

Transport Bar

The transport bar sits at the top of the screen and contains:

• Play/Pause — Start or pause playback. Long-press to restart the song from the beginning.
• Stop — Stop playback and reset the playhead.
• BPM — Shows the current tempo. Tap +/- to adjust by 1 BPM, or drag vertically on the number to scrub the tempo smoothly.
• Undo / Redo — Roll back or reapply pattern editing changes. Undo history is cleared when loading a new project.
• Waveform icon — Open the Instruments panel.
• Music note icon — Open the Scale editor to set the global musical scale.
• Slider icon — Open the Mixer.
• Export icon — Export the current clip or full song to audio.
• Loop icon — Toggle song loop on/off. When lit, the song loops back to the start row at the end. When off, playback stops.
• Folder icon — Open the Project browser.

Breadcrumb Navigation

Below the transport controls, breadcrumbs show your current location in the song hierarchy: Song → Sequence → Clip. Tap any breadcrumb to navigate back to that level. When viewing a clip, the breadcrumb row also shows a STEP / EUCLID mode picker to toggle between the traditional step grid and the Euclidean rhythm editor.

Tracker Grid

The main grid displays the current clip for each track. Each column represents a track, and each row is a step. The columns within each track show:

• Note — The musical note (e.g., C-4, F#5) or OFF for note-off
• Instrument — Which instrument to trigger (hex value: 00-7F)
• Volume — Step volume (hex value: 00-FF)
• FX — Up to 3 effect commands per step

Tap a cell to edit it. Long-press for copy/paste/clear options.

Clips & Steps

Clips are the building blocks of your music. Each clip contains 16 steps, and the sequencer plays them from top to bottom. There are 256 clips available (indexed 00 to FF in hexadecimal), shared across all tracks.

Step Editor

Tapping a cell in the tracker grid opens the step editor. Here you can set:

• Note — Choose from the available notes in the current scale. In Chromatic mode, all 120 MIDI notes (C0 to C9) are available. When a scale is set, the picker shows only in-scale notes. Select OFF to send a note-off command that releases the current note.
• Instrument — Select which instrument this step triggers. If left empty, the step uses the track's last-set instrument.
• Volume — Override the note velocity for this step (00 = silent, FF = maximum).
• Effects 1-3 — Up to three effect commands. Each has a type letter and a hex value. See the Step Effects Reference for details.

Copy, Paste, and Clear

Long-press on any step to bring up the context menu. You can copy a step's contents, paste from the clipboard, or clear the step entirely.

Euclidean Rhythms

SlicBeat includes a Euclidean rhythm generator that uses Bjorklund's algorithm to distribute hits as evenly as possible across a given number of steps. This produces the rhythmic patterns found in music traditions worldwide — from West African bell patterns to Latin clave rhythms.

Entering Euclidean Mode

When viewing a clip, tap the EUCLID button in the transport bar breadcrumb row to switch from step editing to the Euclidean ring editor. If the clip is empty, it switches immediately. If the clip already has steps, a confirmation alert appears since switching will overwrite the existing step data.

The Ring Visualizer

The Euclidean editor displays a circular ring with nodes arranged clockwise, step 0 at 12 o'clock. Active hits are connected by a polygon. Node colors indicate their state:

• Green (filled) — Algorithm-generated hit
• Orange (filled) — Manually added hit (user override)
• Red (hollow ring) — Muted hit (was an algorithm hit, manually silenced)
• Dark — Inactive step

During playback, a sweep line rotates from the center to the current step, and the active node scales up with a brighter glow.

Parameters

Five drag knobs control the pattern:

A horizontal note selector below the knobs sets the MIDI note for all hits (C-2 through C-7).

Muting & Adding Hits

Tap any node on the ring to override the algorithm:

• Tap an active hit — Mutes it (turns red hollow). The algorithm still considers it a hit position, but it won't sound.
• Tap an inactive step — Adds a manual hit (turns orange). This adds a hit the algorithm didn't generate.
• Tap an overridden node — Resets it back to the algorithm's default state.

Overrides are cleared when you change the HITS knob, since the base pattern changes.

Auto-Bake

Every parameter change immediately writes the resolved pattern into the clip's step data. There is no separate "bake" step — what you see on the ring is always what the sequencer plays. Switch back to STEP mode to see the baked steps in the traditional tracker grid. The Euclidean parameters are preserved on the clip, so you can switch back to EUCLID mode later to continue editing.

Sequences

Sequences link multiple clips together into a longer pattern. Each sequence can hold up to 16 entries, where each entry references a clip and optionally applies a transpose value (in semitones). This lets you reuse the same clip at different pitches.

Navigate to the Sequence view by tapping the sequence breadcrumb in the transport bar. Select which clip plays at each position, and set transpose values to create melodic variations without duplicating clips.

Song Mode

The Song view is the top-level arrangement. It's a grid of up to 256 rows × 8 tracks. Each cell references a sequence. The sequencer plays each row from left to right (all 8 tracks simultaneously), then moves to the next row.

Navigate to Song mode by tapping the "Song" breadcrumb. Assign sequences to each track at each row to build your full song structure. Empty cells are silent for that track.

Song Start Row

Long-press a row number in the Song grid to set the start row. Playback will begin from this row instead of row 0. The start row is highlighted in green. Long-press the same row again to reset it back to 0.

Song Loop

During playback, the song progresses row by row. When it reaches the end of the populated rows, it loops back to the start row. Use the loop toggle (repeat icon) in the transport bar to enable or disable looping. When looping is off, playback stops at the end of the song.

Instruments

SlicBeat supports four instrument types, all accessible from the Instruments panel.

Sample Instruments

Load audio samples and play them back at different pitches. Supported formats: WAV, AIF, AIFF, MP3, M4A, CAF. A built-in waveform editor displays the sample with visual slice markers and loop region highlighting.

Sample instrument parameters:

• Volume — Base playback volume
• Panning — Stereo position (left to right)
• Pitch / Base Note — The note at which the sample plays at its original pitch. Notes above or below are resampled.
• Detune — Fine pitch offset (M8-style hex: 0x80 = center)
• Degrade — Bit crush and sample rate reduction (00 = clean, FF = max)
• Slice Count — Divide the sample into equal slices (0 = off, 1-64). Select slices via the Sample Offset (O) step effect.

Sample Playback Modes

Loop Start, Loop End, and Loop Crossfade controls define the loop region and crossfade length for smooth looping.

Volume shaping for samples comes from the modulation system. Use a Drum Envelope, AHD, or ADSR modulator targeting Volume to control how notes attack and decay.

Looms Synth

Create a synthesizer powered by the Mutable Instruments Plaits engine. Choose from 21 synthesis algorithms across four categories:

Classic Synthesis: Virtual Analog + VCF, Phase Distortion, Waveshaping

Digital Synthesis: Granular, Additive, Wavetable, Wave Terrain, Harmonic Chord, Speech Synthesis, Chiptune, String Machine

Physical Modeling: Physical String, Modal Resonance, Particle Swarm, Noise Generator, Particle Synthesis

Drum Synthesis: Bass Drum, Snare Drum, Hi-Hat

Each Looms engine exposes three core parameters:

• Harmonics — Controls harmonic content and overtone structure
• Timbre — Shapes the tonal character of the sound
• Morph — Smoothly morphs between synthesis modes within the engine

MIDI Instruments

Route note data to external MIDI hardware or virtual MIDI apps. Configure the MIDI channel (1-16) and select the destination from available MIDI outputs. MIDI instruments send note-on, note-off, and velocity information in real-time.

SB-303 Acid Synth

A dedicated acid bass synthesizer inspired by the Roland TB-303. Unlike the Looms engines, the SB-303 has its own internal oscillator, filter, and envelope architecture optimized for classic acid basslines.

Signal Path

Single oscillator → 18dB diode ladder filter → VCA with accent → output distortion. The filter has its own attack/decay envelope with adjustable modulation depth.

Parameters

Accent & Slide

Use the AC (Accent) step effect to boost specific notes. Accented steps get louder with a more aggressive filter envelope. Slide is triggered automatically when consecutive notes overlap (legato playing) — the pitch glides smoothly between notes at the configured slide time.

Modulation System

Each instrument has 4 modulation slots. Every slot connects a source (6 types) to a destination with an adjustable amount (-100% to +100%). Modulators can also cross-modulate each other for complex evolving textures.

Modulation Sources

AHD Envelope (Attack-Hold-Decay)
A three-stage envelope that rises, holds, then falls. Parameters: attack time, hold duration, decay time. When all volume-targeting AHD envelopes finish, the voice automatically stops.

ADSR Envelope (Attack-Decay-Sustain-Release)
A classic four-stage envelope. Parameters: attack time, decay time, sustain level, release time. The sustain stage holds as long as the note is on; release triggers on note-off.

LFO (Low-Frequency Oscillator)
A cyclical modulator with six waveform shapes: Triangle, Sine, Ramp Down, Ramp Up, Square, Random. Control the rate, or set a tempo-synced period in 16th-note steps. Three trigger modes:

• Free — Runs continuously regardless of note events
• Retrig — Resets phase on each new note
• Once — Plays one cycle then stops

Tracking
Maps an input value (note pitch or velocity) to the modulation output with configurable input and output ranges. Useful for velocity-sensitive volume or pitch-dependent filter sweeps.

Drum Envelope (Peak-Body-Decay)
A percussion-optimized envelope inspired by the M8 tracker. The Peak control sets both the transient spike amplitude and post-peak duck depth — higher values create a sharp initial hit that dips below unity before recovering. Body time controls an exponential swell back toward full level, and Decay sets an exponential fade to silence. Ideal for shaping kick drums, percussive plucks, and punchy bass sounds.

Trig Envelope (Attack-Hold-Decay, externally triggered)
An AHD envelope that fires when another track or instrument plays a note. Select a source track or instrument from the picker. Parameters: attack, hold, and decay time. Enables sidechain-style effects like volume ducking when a kick plays, or triggered filter sweeps from another pattern.

Cross-Modulation

Modulators can modulate each other for complex, evolving sounds. Set a modulator's destination to one of three cross-mod modes:

• MOD AMT — Scales the neighboring modulator's amount (0-100%)
• MOD RATE — Multiplies the neighboring modulator's time-based rates
• MOD BOTH — Affects both amount and rate simultaneously

Routing is circular: each modulator affects the next, with Mod 4 wrapping back to Mod 1. Use this to create wobbling LFO rates, envelope-controlled vibrato depth, or rhythmic modulation patterns.

Modulation Destinations

• Volume — Multiplies the instrument volume (available for all types)
• Pitch — Offsets the pitch in semitones (available for all types)
• Filter Cutoff — Modulates the filter cutoff frequency (sample & Looms)
• Filter Resonance — Modulates filter resonance (sample & Looms)
• Harmonics — Modulates the Looms harmonics parameter (Looms only)
• Timbre — Modulates the Looms timbre parameter (Looms only)
• Morph — Modulates the Looms morph parameter (Looms only)
• MOD AMT — Scales the neighboring modulator's amount (cross-mod)
• MOD RATE — Multiplies the neighboring modulator's rate (cross-mod)
• MOD BOTH — Affects both amount and rate of the neighbor (cross-mod)

Filters

Each sample and Looms instrument has an optional filter section with 7 filter types:

Standard Filters

• Low Pass — Removes frequencies above the cutoff, creating darker tones
• High Pass — Removes frequencies below the cutoff, thinning out the low end
• Band Pass — Passes only a narrow band around the cutoff frequency
• Notch — Removes a narrow band around the cutoff, passing everything else

Vintage Emulations

• MS-20 Low Pass — Inspired by the Korg MS-20. A 12dB/octave filter with aggressive resonance and tanh saturation in the feedback path, creating the characteristic screaming self-oscillation.
• Oberheim SEM — Inspired by the Oberheim SEM. A 12dB/octave state-variable filter with gentle, musical resonance. Known for its smooth, warm character.
• Moog Ladder — Inspired by the Moog transistor ladder. A 24dB/octave (4-pole) cascade filter with rich, creamy resonance. The classic subtractive synthesis filter.

Each filter has two main controls:

• Cutoff — The filter frequency (0-100%)
• Resonance — How much the filter emphasizes frequencies near the cutoff (0-100%)

When you enable a filter, SlicBeat automatically creates an ADSR envelope → Filter Cutoff modulator in the first available modulation slot. This gives you immediate envelope control over the filter without manual setup. You can adjust the ADSR parameters and amount from the Modulation section, or remove it if you prefer a static cutoff.

Parametric EQ

SlicBeat includes a 3-band parametric EQ system backed by 128 shared EQ bank slots. Banks can be assigned to instruments, effect returns (delay, reverb, mod FX), and the master output. All processing uses Robert Bristow-Johnson's Audio EQ Cookbook biquad formulas.

EQ Banks

The EQ bank pool contains 128 slots (indexed 00-7F). Each bank stores a complete 3-band EQ configuration. Banks are shared across the project, so the same bank can be reused on multiple instruments or bus points. Assign a bank by selecting its index from the EQ bank picker on any instrument or mixer bus.

Band Parameters

Each bank has three bands labeled LOW, MID, and HIGH. Every band has four parameters:

Filter Types

Assignment Points

EQ banks can be assigned at the following points in the signal chain:

• Instrument — Per-instrument EQ applied post-filter, pre-send. Set from the instrument editor.
• Delay Return — EQ on the delay effect output. Set from the mixer.
• Reverb Return — EQ on the reverb effect output. Set from the mixer.
• Mod FX Return — EQ on the modulation effect output. Set from the mixer.
• Master Output — EQ on the final stereo bus before export/playback. Set from the mixer.

Frequency Response Curve

The EQ editor displays a real-time Canvas-drawn frequency response curve showing the combined effect of all three bands. The curve updates as you adjust parameters, giving immediate visual feedback of the filter shape.

Scale System

SlicBeat has a global musical scale that constrains all notes to a chosen key and mode. This affects note entry, note scrubbing, and playback (transpose and arpeggio are quantized to the scale). The default scale is Chromatic, which allows all 12 semitones and behaves like having no scale constraint at all.

Opening the Scale Editor

Tap the music note icon in the transport bar to open the Scale editor sheet. It contains four sections:

• Key — A segmented picker to select the root note (C, C#, D, D#, E, F, F#, G, G#, A, A#, B).
• Scale — A list picker to choose from 10 scale modes.
• Notes in Scale — A visual grid showing which of the 12 semitones are enabled in the current scale.
• Mini Keyboard — A one-octave piano visualization highlighting the in-scale keys.

Available Scale Modes

How Scale Affects Your Music

• Note Picker — The step editor note picker shows only notes that belong to the current scale. Switching from Chromatic to C Major reduces the picker from 120 options to 70 in-scale notes.
• Note Scrubbing — Dragging to change notes in the clip grid steps through only in-scale notes, skipping out-of-scale pitches.
• Transpose Quantization — When sequences transpose a clip, the resulting notes are snapped to the nearest in-scale pitch during playback.
• Arpeggio Quantization — The arpeggio effect (A command) quantizes its offset notes to the current scale, keeping arpeggiated chords in key.

Scale Bypass

Individual instruments can be exempted from the global scale using the Scale Bypass toggle in the Instrument Editor. When enabled, the instrument ignores the global scale constraint and allows all 12 chromatic notes. This is useful for drum instruments or sound effects that shouldn't be quantized to a key.

Changing Scale Mid-Song

Scale changes take effect immediately. If you change the scale while a song is playing, all new notes from that point forward use the updated scale. Already-sounding notes are not affected until they retrigger.

Backward Compatibility

Projects created before the scale system was added automatically default to Chromatic mode, so all existing songs play exactly as they did before.

Step Effects Reference

Each step can have up to 3 effect commands. Each command consists of a type code and a hexadecimal value (00-FF).

Global Effects

SlicBeat has three global send effects. Each track has independent send levels, so you can blend the effect amount per track.

Delay

A stereo ping-pong delay where audio bounces between left and right channels. Delay times are encoded as hex values where the first digit is beats (quarter notes) and the second digit is additional 16th-note subdivisions. For example, 04 = 1 beat, 06 = dotted quarter, 40 = 4 beats.

Parameters:

• Volume — Wet signal level
• Time L — Left channel delay time (hex, BPM-synced)
• Time R — Right channel delay time (hex, BPM-synced)
• Feedback — How much signal feeds back into the delay (0-100%, clamped to 95%)
• Width — Stereo spread (0 = mono center, max = full L/R separation)
• Rev Send — Amount of delay output routed into the reverb for lush delay+reverb trails

Reverb

A vintage-style plate reverb with shimmer. Features input diffusion, dual cross-coupled modulated tanks, and an octave-up pitch shifter in the feedback path.

• Volume — Wet signal level
• Size — Scales the virtual room size (0-100%)
• Decay — Reverb tail length (0-100%)
• Shimmer — Octave-up pitched feedback for ethereal, rising tails (0-100%)
• Mod Depth — Tank delay modulation depth for richer, less metallic tails
• Mod Freq — Speed of the tank modulation LFO
• Width — Stereo spread of the reverb output

Mod FX

Three stereo modulation effect algorithms, selectable per project. Dual LFOs with 90° offset drive L/R channels for natural stereo decorrelation.

• Chorus — Thick, lush doubling via stereo modulated delays (5-25ms range)
• Phaser — Dual 6-stage allpass chains sweeping 200-4000 Hz for wide phase shifting
• Flanger — Stereo comb-filter effect with short modulated delay (0.5-5ms) and feedback

Parameters (shared across all three):

• Volume — Wet signal level
• Depth — Intensity of the modulation
• Freq — LFO speed of the modulation (0.1-8 Hz)
• Width — Stereo spread (0 = mono, max = full stereo)
• Rev Send — Amount of mod FX output routed into the reverb

Mixer

The Mixer gives you control over the final mix. Open it by tapping the slider icon in the transport bar.

Master Section

• Volume — Master output level (0-100%). Can be automated with the MV step effect.
• EQ — Select an EQ bank for the master output bus.
• Limiter — Toggle and release control for the master limiter. Enabled by default.

Per-Track Controls

• Volume — Track output level (0-100%)
• Pan — Stereo position (full left to full right)
• Mute — Silence the track without removing it from the arrangement
• Solo — Listen to only this track (mutes all others). Multiple tracks can be soloed simultaneously.

Send Levels

Each track has independent send amounts for the three global effects:

• Delay Send — How much of the track goes to the delay effect
• Reverb Send — How much of the track goes to the reverb
• Mod FX Send — How much of the track goes to the modulation effect

EQ on Effect Returns & Master

The mixer provides EQ bank pickers on each effect return (delay, reverb, mod FX) and the master output. Select a bank index to apply a 3-band parametric EQ at that point in the signal chain. This lets you shape the tonal character of your effects and final mix without affecting individual instruments.

Master Limiter

The master limiter prevents the output from exceeding 0 dBFS, protecting against digital clipping when multiple tracks and effects combine. It sits at the very end of the signal chain, after the master EQ and master volume.

• Limiter Toggle — Enabled by default. Turn off to bypass the limiter entirely.
• Release — Controls how quickly the limiter recovers after reducing gain. Lower values (faster release) respond quickly to transients. Higher values (slower release) produce smoother, more transparent limiting.

Instrument Presets

Instrument presets let you save and reuse instrument configurations across different projects.

Saving a Preset

Open any instrument in the Instrument Editor, scroll down to the Presets section, and tap Save as Preset. Give it a name, and the complete instrument configuration (type, parameters, modulation slots, filter settings) is saved.

Loading a Preset

There are two ways to load a preset:

• From the + menu — Tap + in the Instruments panel and choose "Load Preset" to create a new instrument from a saved preset.
• From the Instrument Editor — Open an existing instrument, scroll to the Presets section, and tap "Load Preset" to replace the current instrument's settings with a saved preset.

Presets include all instrument settings: Looms engine and parameters, sample filename, filter configuration, and all four modulation slots. Sample files must still be available in the project for sample-based presets to load correctly.

Project Management

Creating a Project

Tap the folder icon in the transport bar to open the Project browser. Tap + to create a new project. Each project gets its own directory for samples and settings.

Saving

Projects auto-save a few seconds after each edit, and also when the app moves to the background. The project file is stored as JSON alongside any imported samples. You can also save manually via the save button in the transport bar.

Auto-Load

SlicBeat remembers your last project and automatically loads it on launch. Sample buffers load asynchronously in the background for faster startup times.

Managing Projects

The Project browser shows all saved projects sorted by modification date. Swipe to delete projects you no longer need.

Audio Export

Export your music as audio files directly from SlicBeat. Tap the export icon in the transport bar to open the export sheet.

Export Modes

• Clip Export — When viewing a clip, exports just that clip as a loop. Useful for creating samples or sharing individual patterns.
• Song Export — When in song or sequence view, exports the full song arrangement with all tracks, effects, and mix settings.

Formats

• WAV — Uncompressed 16-bit PCM audio. Best quality, larger file size. Ideal for importing into a DAW.
• M4A — AAC-encoded audio at 256 kbps. Smaller file size, good for sharing.

After export, the iOS share sheet appears so you can save to Files, AirDrop, or share to any app.

Undo & Redo

SlicBeat provides snapshot-based undo and redo for pattern editing. Before each edit, the full project state is saved so you can roll back changes instantly. Undo and redo sync with the audio engine in real-time, so changes are heard immediately even during playback.

• Undo — Tap the undo arrow in the transport bar to revert the last edit.
• Redo — Tap the redo arrow to reapply an undone change.

The undo stack holds multiple levels of history. It is cleared when you load a different project to keep memory usage low.