OH-84 Lite Quickstart Guide

A fast guide to playing OH-84 Lite on a desktop or larger tablet browser, using touch, mouse, or a computer keyboard.

Start Playing

Turn on the instrument

Press POWER. The audio light comes on and the display changes from OFF. Browsers need this first action before sound can play.

Choose a chord

Use the Major, Minor, or 7th chord rows. With HOLD on, the chord and bass continue until you choose another chord or use Instant Off.

Strum the plate

Drag up and down the strumplate. Low notes are at the bottom and high notes are at the top, like the real vertical plate.

Chord Buttons

Basic chords

Button row	Result
Major	Major chord
Minor	Minor chord
7th	Dominant seventh chord

Combination chords

Buttons together	Result
Major + 7th	Major seventh
Minor + 7th	Minor seventh
Major + Minor	Diminished
Major + Minor + 7th	Augmented

For combination chords, the computer keyboard is usually the easiest way to press two or three chord buttons at once.

Main Controls

Voice mix

Balances the clean strumplate voice and the modulated second voice. Fully left is Voice 1. Fully right is Voice 2.

Sustain

Changes how long the strumplate notes ring. Turn it up for a smoother, more floating sound.

Level mix

Balances chord and bass against the strumplate. Move left for stronger chord/bass, or right for stronger strumplate.

Drag vertically on a rotary control to turn it. Drag up to increase the control, or down to reduce it. Arrow keys also work when a knob has focus.

Computer Keyboard Controls

Chord keys

Each row follows the chord buttons from left to right: Db, Ab, Eb, Bb, F, C, G, D, A, E, B, F#.

Major

QWERTYUIOP[]

Minor

ASDFGHJKL;'\

7th

ZXCVBNM,./Right ShiftRight Ctrl

Strum and stop

The top keyboard row plays the 13 strumplate bars from low to high.

`1234567890-=

Instant Off

Delete

Instant Off stops the currently sounding chord and bass immediately.

Computer Keyboard Map

The keyboard map shows the chord rows as they sit under your fingers, with Major, Minor and 7th chords mapped across the computer keyboard.

Open full keyboard map

Keyboard Mode

Playing notes

Press KEYBOARD to turn the chord buttons into a two-octave keyboard. The strumplate is inactive while keyboard mode is on.

The lowest note is C4 on the Db 7th button. The notes progress chromatically up to G5 on the F# 7th button.

Transpose

In keyboard mode, press the T button on Db Major to arm transpose. Use the down arrow on Eb Major or the up arrow on Bb Major to move in semitone steps.

The display shows values such as T+6 or T-3. Transpose can move up to one octave each way and affects the whole instrument when you return to chord mode.

Lite Version Notes

Included

OH-84 Lite includes the 84 chord layout, dual-voice strumplate, chord/bass sound, hold, instant off, keyboard mode, and transpose.

Reserved controls

MIDI, patterns, chord computer, MIDI file player, skins, and save are shown on the panel but are not active in this Lite build.

Audio tip

Wired headphones or device speakers usually feel most immediate. Bluetooth speakers and headphones can add a small delay.

Technical Specification

The OH-84 is the expanded browser instrument for desktop, laptop and larger tablet screens.

Open OH-84 Lite technical specification

Audio engine	Web Audio API, tuned for fast browser response.
Platform	Browser-based instrument for desktop, laptop and larger tablet screens. Not intended as a phone layout.
Chord layout	84 chord-button layout: 12 roots across Major, Minor and 7th rows.
Root order	Db, Ab, Eb, Bb, F, C, G, D, A, E, B, F#.
Chord types	Major, Minor, 7th, Major 7th, Minor 7th, Diminished and Augmented.
Combination chords	Major + 7th = Major 7th. Minor + 7th = Minor 7th. Major + Minor = Diminished. Major + Minor + 7th = Augmented.
Diminished voicing	Classic Omnichord-style diminished behaviour: dim7 character with the 5th omitted, supported by the root bass note.
Chord voicing	Custom inversion table to keep chord movement musically centred and reduce large jumps between chords.
Bass layer	Dedicated bass oscillator with chord-following root notes and level balancing against chord/strum layers.
Strumplate	13-note vertical strumplate, low notes at the bottom and high notes at the top.
Strum voices	Dual 13-note strum voice banks: Voice 1 clean, Voice 2 modulated.
Voice 2 modulation	Sample-informed modulation with pitch movement and approximately 4 Hz amplitude movement.
Oscillators	Pre-created, always-running oscillator banks with gain-envelope triggering for fast response.
Waveform	Custom PeriodicWave profiles for strum, chord and bass tones, shaped toward an Omnichord-style harmonic character.
Output shaping	Soft clipping and dynamics compression for a more cohesive, hardware-like output.
Envelope	Fast attack with adjustable strumplate decay. Base strum decay is around 1.4 seconds before sustain control scaling.
Controls	Master volume, Voice mix, Strum sustain, Level mix, Hold, Power and Instant Off.
Hold	Holds the current chord and bass until another chord is selected or Instant Off is used.
Instant Off	Immediately stops the sounding chord and bass. Also mapped to the Delete key.
Keyboard control	Full computer-keyboard chord mapping, with C centred on the Y key. Top keyboard row controls the strumplate.
Keyboard mode	Turns the chord buttons into a chromatic keyboard from C4 to G5. The strumplate is inactive while Keyboard mode is on.
Transpose	Keyboard-mode transpose control from -12 to +12 semitones. Transpose affects the whole instrument when returning to chord mode.
Input system	Pointer, mouse, touch and computer-keyboard input, with page gestures suppressed for stable instrument use.
Display	Current chord/status display with transpose state readout.
Lite restrictions	MIDI, patterns, chord computer, MIDI file player, custom skins and save/export are shown as reserved controls but inactive in Lite.
Compatibility	Modern Chromium, Edge, Safari and Firefox-style browsers with Web Audio support. Best with wired headphones or built-in speakers for lowest latency.
Identity	Independent Omnichord Heaven browser instrument inspired by the classic OM-style layout and playing method.

Open OH-84 Lite Back to Omnichord Online Best on desktop, laptop, or a larger tablet browser.