Polyphonic instrument

• Generator
• Since 0.2.0
• instrument
• voices
• keyboard
• adsr
• tuning
• microtonal
• mpe

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A ready-made eight-voice instrument. It has no audio input: it makes sound when it receives notes from a Frame piano, the computer keyboard or MIDI, and sends a stereo signal out.

What it does#

Each note takes one of eight voices. A voice is an oscillator with its own attack, decay, sustain and release, so overlapping notes keep their own envelopes. The instrument responds to note velocity and to the sustain pedal. Level is shared across the voices: each voice receives one eighth of it, so playing eight notes together has fixed headroom.

It does not take an audio input or modulation cables. Effects go after it on the output cable.

Pitch and tuning#

The keys play the Toy's tuning: a preset such as 31-EDO or just intonation, or a custom table of cents. Without one the Toy plays 12-TET with A4 at 440 Hz, and note 69 is A4.

• Equal divisions of the octave (12-TET, 19-, 22-, 24-, 31- and 53-EDO): middle C (MIDI 60) is degree 0, each key up is one step, and A4 stays at the reference on the degree three of the division's own fifths above C. In 31-EDO, C4 to C5 spans 31 keys.
• Just, Pythagorean, Bohlen–Pierce and custom tables: MIDI 60 plus Root plays the root at its 12-TET pitch from the reference, and each key up is the next degree, repeating at the period (an octave, or a tritave for Bohlen–Pierce).

The engine maps all 128 notes once when the Toy is prepared, so a note-on only reads a table. Pitch bend is ±2 semitones, except on MPE member channels (below). The tuning is set in the Toy's source, for example "tuning": { "preset": "31-edo", "root": 0, "reference": 440 }; the Thirty-One Keys example Toy plays that one. A Tuner left on Toy tuning measures against the same degrees.

Voices and stealing#

A note takes the voice already playing that key from the same source and channel, else a silent voice, else the oldest released voice, else the oldest held one. A stolen voice crossfades to its new note over 32 samples. Each MIDI source (a Frame piano, the computer keyboard, each MIDI device) owns its own notes and sustain pedal per channel, so one source releasing a key never silences another's.

MPE#

With MPE set to Lower zone (master channel 1, members 2–16) or Upper zone (master channel 16, members 1–15), each note arrives on its own member channel. That channel's pitch bend then moves only the voice holding its note, by up to MPE bend semitones; master-channel bend still moves every voice by ±2 semitones, and the two add. Pressure and CC74 have no target in this instrument; build a polyphonic group to route them per voice. MPE configuration messages (MCM) and MIDI-CI are not handled: set the zone here to match the controller.

When to use it#

Use it when you want something playable with a few controls and no wiring: a starting point for keyboards, pads and plucks. Reach for Oscillator with an Envelope when you need a single voice you can wire and modulate yourself, and give its group voices to play chords with it.

Ports#

Parameters#

Level (amplitude)#

Master level of the instrument. Because each voice gets one eighth, raising it never makes a full chord clip on its own.

Shape (shape)#

A continuous morph: 0 is sine, 1 is triangle, 2 is saw and 3 is pulse. Values between blend neighboring waves.

Attack (attack_ms), Decay (decay_ms), Sustain (sustain), Release (release_ms)#

The per-voice envelope. Attack, Decay and Release are times in milliseconds. Sustain is the level, shown from 0 to 100 %, that a held key stays at after the decay. Release starts at note-off, or when the sustain pedal is let go.

Fine tune (detune)#

Moves every note of this instrument by up to 100 cents either way from the Toy's tuning; 0 plays the tuning as written. Two instruments a few cents apart thicken a sound. The tuning itself, including the A4 reference, belongs to the Toy (see Pitch and tuning).

Pulse width (pulse_width)#

The duty cycle of the pulse wave, from 0.05 to 0.95. It affects the sound near the pulse end of Shape.

MPE (mpe)#

Off treats every channel alike. Lower zone and Upper zone make channel 1 or channel 16 the master and the other fifteen member channels, one per sounding note (see MPE).

MPE bend (mpe_bend)#

How far a full pitch bend on a member channel moves its note, 0 to 96 semitones each way; 48 is the MPE default most controllers send. It applies only while MPE is on.

Tips#

• Short Attack and Release sound plucked; long ones sound like a pad.
• Sustain of 0 makes a note die away after the decay even while the key is held.
• Add Reverb after the instrument for space.
• Frame pianos and MIDI both reach the instrument. See MIDI.
• To hear a microtonal scale, give the Toy a tuning and play neighbouring keys: each is one degree.

See also#

Oscillator, Envelope, Reverb, Tuner, Frames, Voices.

Help patches

Each help patch is an ordinary Toy that teaches one idea. The diagram shows the Patch; the preview shows its Frame. Open it in TuneToys to play and edit it.

1. Play a chord with the keyboard

beginner Teaches: shape, amplitude

An eight-voice instrument with a piano and a waveform choice.

Connections as text

• Polyphonic instrument audio output connected to Patch outputs audio input
• Keyboard midi output connected to Polyphonic instrument midi input

• Play several keys at once. Each key takes its own voice, up to eight.
• Shape morphs from sine to triangle to saw to pulse. Level sets the whole instrument.

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2. Shape the note with ADSR

intermediate Teaches: attack_ms, decay_ms, sustain, release_ms

Attack, decay, sustain and release for every voice.

Connections as text

• Polyphonic instrument audio output connected to Patch outputs audio input
• Keyboard midi output connected to Polyphonic instrument midi input

• Raise Attack for a slow swell and Release for a note that fades after you let go.
• Sustain is a level, not a time: it is the volume held while a key stays down.

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3. Fine tune and pulse width

advanced Teaches: detune, pulse_width

Detune every voice by cents and change the pulse duty cycle.

Connections as text

• Polyphonic instrument audio output connected to Patch outputs audio input
• Keyboard midi output connected to Polyphonic instrument midi input

• Pulse width only changes the sound while Shape is near the pulse end of its range.
• Fine tune moves every key together by cents from the Toy's tuning. 0 plays the tuning as written.

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4. MPE zones

advanced Teaches: mpe, mpe_bend

Choose an MPE zone so each member channel's pitch bend moves only its own note, by up to MPE bend semitones.

Connections as text

• Keyboard midi output connected to Polyphonic instrument midi input
• Polyphonic instrument audio output connected to Patch outputs audio input

• An MPE controller sends each note on its own member channel. With a zone set, that channel's bend moves only its note; channel 1 (lower) or 16 (upper) bends them all.

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Related nodes

• Oscillator Selected waveform kernels, continuous morphing, harmonic shapes and phase/gate control; an optional MIDI input plays notes in the Toy's tuning.
• Envelope Curved AD, AR and ADSR gain envelopes with looping and explicit retrigger behavior.
• Reverb An eight-line modulated feedback-delay network with room, hall and plate-like tunings.
• Tuner Passes audio through unchanged and shows the nearest degree of a microtonal tuning on its face. Mute silences it like a tuner pedal.