Purpose

Synth is a polyphonic subtractive synthesizer for leads, pads, and bass. It provides band-limited oscillators (saw, square, triangle, sine), a Cytomic TPT state-variable filter with key tracking and envelope modulation, unison detuning, a sub oscillator, ADSR envelope, drive, and stereo spread.

Use

Wire note_voices_f32_v1 from MIDI Note, a chord voicer, an arpeggiator, or any note-voice source into the voices input. Choose a waveform, set the filter, shape the envelope, and wire the stereo audio output to Device Out, an effect chain, or a mixer.

Inputs and outputs

• Input 0: voices — note_voices_f32_v1 (required). Gate, pitch, velocity, and aftertouch per voice.
• Output 0: out — stereo audio (PCM f32).

Controls

• Waveform — Oscillator shape: saw, square, triangle, or sine. All shapes are band-limited with PolyBLEP anti-aliasing.
• Gain — Master output level.
• Unison — Number of detuned oscillators per voice (1-7).
• Detune — Unison detune spread in cents.
• Sub — Sub oscillator level (sine, one octave below the fundamental).
• Pulsewidth — Pulse width for the square waveform (0.05-0.95).
• Cutoff — Filter cutoff (0-1, mapped to 20 Hz-20 kHz logarithmically).
• Resonance — Filter Q (0-1, mapped to 0.5-20).
• Filtermode — Filter type: lowpass, highpass, bandpass, or notch.
• Filterenv — Filter envelope modulation amount (-1 to +1). Positive values open the filter on attack; negative values close it.
• Attack / Decay / Sustain / Release — ADSR envelope (milliseconds for A/D/R, 0-1 for sustain level).
• Drive — Post-filter saturation.
• Width — Stereo spread of unison voices.
• Keytrack — Filter cutoff key tracking amount (0-1). At 1.0, the filter follows the keyboard pitch.
• Limiter — Output safety limiter.

Notes

• Up to 8 polyphonic voices.
• The filter is a topology-preserving Cytomic SVF that remains stable at high resonance and fast modulation.
• Velocity controls output amplitude (30% floor + 70% velocity scaling).
• Glide between notes uses a simple exponential smoothing (5% per sample step).

Ports

Inputs

• voices row required
  note_voices_f32_v1

Outputs

• out row
  audio_pcm_f32_stereo_v1

Parameters

Waveform (Waveform) Menu op('synth').par.Waveform

Default:

saw

Options:

saw, square, triangle, sine

Gain (Gain) Float op('synth').par.Gain

Default:

0.5

Range:

0 to 2

Unison (Unison) Int op('synth').par.Unison

Default:

3

Range:

1 to 7

Detune (Detune) Float op('synth').par.Detune

Default:

12

Range:

0 to 50

Sub (Sub) Float op('synth').par.Sub

Default:

0.2

Range:

0 to 1

Pulsewidth (Pulsewidth) Float op('synth').par.Pulsewidth

Default:

0.5

Range:

0.05 to 0.95

Cutoff (Cutoff) Float op('synth').par.Cutoff

Default:

0.65

Range:

0 to 1

Resonance (Resonance) Float op('synth').par.Resonance

Default:

0.2

Range:

0 to 1

Filtermode (Filtermode) Menu op('synth').par.Filtermode

Default:

lowpass

Options:

lowpass, highpass, bandpass, notch

Filterenv (Filterenv) Float op('synth').par.Filterenv

Default:

0.3

Range:

-1 to 1

Attack (Attack) Float op('synth').par.Attack

Default:

5

Range:

0 to 5000

Decay (Decay) Float op('synth').par.Decay

Default:

200

Range:

0 to 5000

Sustain (Sustain) Float op('synth').par.Sustain

Default:

0.7

Range:

0 to 1

Release (Release) Float op('synth').par.Release

Default:

300

Range:

0 to 10000

Drive (Drive) Float op('synth').par.Drive

Default:

0.15

Range:

0 to 1

Width (Width) Float op('synth').par.Width

Default:

0.7

Range:

0 to 1

Keytrack (Keytrack) Float op('synth').par.Keytrack

Default:

0.5

Range:

0 to 1

Limiter (Limiter) Toggle op('synth').par.Limiter

Default:

On

Options:

Off, On