gris

gris is a digital recreation of the famous Throbbing Gristle Gristleizer — a vactrol-based tremolo and voltage-controlled filter. the LFO drives a vactrol envelope follower with asymmetric attack/release, modulating either the VCA amplitude, the filter cutoff, or a blend of both. 10 runtime-selectable waveforms from triangle and ramp to smooth random, stepped random, exponential envelope, and noise. germanium-style diode clipping at the input.

character modes

all six knobs retain identical semantics across all modes — the toggle changes what moves, not what the knobs do.

• classic: original Gristleizer behavior. LFO modulates VCA/VCF at a fixed rate and depth.
• envelope: input signal dynamics modulate LFO depth. playing harder increases tremolo intensity. fast attack (5ms), slow release (200ms). depth controls how much the envelope influences modulation.
• drift: random per-cycle modulation offset. each LFO cycle generates a new random value (±50%) added to the modulation, scaled by depth. at low depth, subtle organic wobble. at high depth, the effect becomes unstable and chaotic.

LFO waveforms

mode routing

• VCA: signal multiplied by vactrol envelope
• VCF: signal passes through; filter cutoff modulated
• MIX: blend of VCA and VCF based on bias knob

vactrol model

asymmetric envelope follower modeling a vactrol’s response:

• attack: 10ms (fast response to signal onset)
• release: 100ms (slow decay, characteristic vactrol behavior)

diode clipping

soft asymmetric clipping modeled on germanium diodes:

• positive half: tanh(x) — smooth saturation
• negative half: tanh(x × 1.1) × 0.9 — slightly harder clipping (asymmetry)