Envelopes & Modulators

Modulation sources shape how parameters change over time, creating movement and expression.

ADSR Envelope

The classic Attack-Decay-Sustain-Release envelope generator.

let env = patch.add("env", Adsr::new(44100.0));

Inputs

Output

Envelope Stages

Level
  5V ┤    ╱╲
     │   ╱  ╲____
     │  ╱        ╲
     │ ╱          ╲
  0V ┼╱────────────╲────
     A    D   S    R

Timing Curves

All stages use exponential curves:

Attack: $$v(t) = 5 \cdot (1 - e^{-t/\tau_a})$$

Decay/Release: $$v(t) = (v_{start} - v_{end}) \cdot e^{-t/\tau} + v_{end}$$

Typical Settings

LFO (Low-Frequency Oscillator)

See Oscillators for full documentation.

Quick reference:

let lfo = patch.add("lfo", Lfo::new(44100.0));
patch.connect(lfo.out("sin"), vcf.in_("fm"))?;

Sample and Hold

Captures input value on trigger pulse.

let sh = patch.add("sh", SampleAndHold::new());

Inputs

Output

Classic Use: Random CV

// Random stepped modulation
patch.connect(noise.out("white_left"), sh.in_("in"))?;
patch.connect(clock.out("div_8"), sh.in_("trigger"))?;
patch.connect(sh.out("out"), vcf.in_("cutoff"))?;

Slew Limiter

Limits rate of change—creates portamento and smoothing.

let slew = patch.add("slew", SlewLimiter::new(44100.0));

Inputs

Output

Applications

flowchart LR
    subgraph "Portamento"
        P1[Pitch CV] --> SLEW1[Slew] --> VCO1[VCO]
    end

    subgraph "Envelope Follower"
        P2[Audio] --> RECT[Rectify] --> SLEW2[Slew]
    end

    subgraph "Smooth Random"
        P3[S&H] --> SLEW3[Slew] --> MOD[Smooth CV]
    end

Quantizer

Snaps continuous CV to scale degrees.

let quant = patch.add("quant", Quantizer::new());

Inputs

Output

Available Scales

Clock

Master timing generator.

let clock = patch.add("clock", Clock::new(44100.0));

Inputs

Outputs

Step Sequencer

8-step CV/gate sequencer.

let seq = patch.add("seq", StepSequencer::new());

Inputs

Outputs

Programming Steps

The sequencer holds 8 CV/gate pairs. In a full application, you’d set these via UI or MIDI.