A browser-based generative music sequencer built with JavaScript and Tone.js, designed for live performance and composition.

▶ Open modal-16

Overview

modal-16 is a 16-step polyphonic sequencer that runs entirely in the browser. It proposes melodies, chord progressions, bass lines, and drum patterns in real time using probabilistic rules and harmonic constraints. Patterns can be shaped, edited, saved, and performed live — the system generates, the composer decides what stays.

Everything runs in a single HTML file with no build step, no dependencies to install, and no server required.

Features

Sequencer

• 16-step patterns for melody, chords, bass, and five drum voices (kick, snare, hi-hat, clap, open hat)
• Per-step note editing with scale-aware dropdowns for pitched tracks
• Per-track mute, hold, level, density, and FX controls

Instruments

• 10 melody voices: Piano, Rhodes, Vibraphone, Bells, Mellotron Flute, Wurlitzer, Kalimba, Supersaw, Juno, Acid 303
• 8 chord voices: Warm Pad, Strings, Organ, Glass, Tape Choir, Cello Ensemble, Brass Stab, Synth Pad
• 7 bass voices: Electric, Sub, Synth, Moog, Fretless, Acid 303, Reese
• Fully synthesized drum kit via Web Audio API

Harmony & Drift

• 5 scales: Dorian, Phrygian, Aeolian, Pentatonic, Mixolydian
• 10 harmonic progressions for automatic root movement
• Pattern drift: incremental mutation of active steps and notes on a configurable bar interval
• Harmonic drift: root transposition through a progression on a configurable interval
• Freeze mode: locks drift until manually released

Performance

• 8 snapshot slots — save and recall full pattern + instrument states
• Chain sequencer — arrange snapshots into sequences with configurable repeat counts
• Stutter (1× and 2×) — momentary step freeze for live rhythmic effects
• Keyboard shortcuts for transport, mute, solo, and stutter

Recording & Scripting

• Audio recording direct from the browser (exports .webm)
• Script recording — captures all parameter changes as a timestamped JSON event log
• Script replay — deterministic playback of a recorded session

FX

• Per-track: LP filter, reverb, delay, stereo spread (melody/chords)
• Master: tape wobble (vibrato), lo-fi low-pass, vinyl noise

Usage

Open index.html in a modern browser. No installation required.

1. Click ▶ PLAY to initialise audio and start the sequencer
2. Use ⟳ NEW PATTERN to generate a random pattern in the current key and scale
3. Edit steps directly — click drum steps to toggle, use dropdowns to set pitched notes
4. Save states to snapshot slots and chain them for structured arrangements
5. Use ⏺ RECORD to capture audio, or ◎ SCRIPT REC to capture a session as a replayable script

Keyboard Shortcuts

Technical

• Vanilla JavaScript, no framework
• Tone.js v14.7.77 for scheduling, synthesis, and effects
• Web Audio API for drum synthesis and recording
• Tone.js CDN loaded from cdnjs; piano samples loaded from tonejs.github.io/audio/salamander/ (external dependency — app falls back to synth mode if unavailable)
• Single file: index.html

Scripts

The scripts/ directory contains replayable session recordings in JSON format. Load any script via ↑ IMPORT SCRIPT and press ▶ REPLAY to play it back.

01-init-script.json is the generative script for 01 init(), the opening track of Yesterday's Tomorrow, Today!

Yesterday's Tomorrow, Today!

Yesterday's Tomorrow, Today! is a twelve-track album recorded entirely with modal-16 by Jeff Ulicny.

Each track is a single live take of the generative system in performance — patterns proposed by the sequencer, shaped in real time through parameter changes, snapshot recalls, and live edits. No post-production, no overdubs. All composition, performance, and recording took place in the browser.

The album title and track names draw from programming terminology to invoke a retro-futuristic sensibility: the sound of futures imagined from the early days of personal computing, built with tools that exist today.

Listen on Bandcamp

About

modal-16 was designed and built by Jeff Ulicny.

License

MIT — free to use, modify, and distribute with attribution.