01 What is Grizzly?

Rhythm and filter, that never quite behaves.

Grizzly is a stereo modulation effect for anything you want. Drums, guitars, synths, vocals, whole busses. It makes sound move in a pattern. An internal LFO (triangle, square, saw up, saw down) drives a modelled JFET stage that can either duck the amplitude of the input (VCA mode) or open and close a lowpass filter across it (VCF mode).

VCA gives you tremolo, hard rhythmic gating, choppy 8th-note pumping, slow breathing swells, and past about 20 Hz, grimy ringmod-adjacent tones. In VCF you get autowah, breathing filter sweeps, dub-wise cutoff pulses, and the sort of muted-then-open motion that usually requires a wah pedal and a foot.

Speed can be set freely or locked to the tempo of your project. The shape of each cycle, whether the movement is smooth and gradual or sudden and hard-edged, is adjustable. Drive loads the signal the way the pedal's op-amp did and adds warmth and grit before the effect touches the sound, the way the original circuit's amplifier stage did. Spread makes the left and right channels move out of step with each other, widening the image between your speakers. for an auto-pan effect. Sync locks the LFO to host tempo down to 1/32 notes.

Use it as an insert on a snare bus for gated pulses, on a Rhodes for wobble, on a pad for a slow filter opening, or across a whole drum kit or even vocals for industrial-flavoured chops.

02 Inspiration

In 1979 David Simpson published a strange little modulator in Electronics & Music Maker: the Gristleizer. A tremolo circuit that behaved a little bite like an instrument - sawtooths and squares, bias and offset, a filter that opened with an LFO.

Chris Carter of Throbbing Gristle wired it into everything he touched, and for forty years numerous clones and eurorack models have built open the design. Grizzly is my interpretation of the circuit: faithful to the circuit's temperament, free of its noise floor and with a few whistles here and there.

Grizzly comes in VST3 and AU formats - no menus, no presets, ten knobs and a bypass. Drop it in and dial it in.

03 Specification

Drive

−12 to +24 dB pre-gain into the modulator

Speed

0.01 Hz to 30 Hz, or host-synced note divisions from 1/1 to 1/32

Depth

Changes the modulation depth

Shape

For Triangle: controls the slope asymmetry, from a fast-rise ramp at 0 through a symmetric V at center to a fast-fall ramp at 1.
For Square: controls how long the wave stays high vs low (duty cycle).
No effect on Saw waves.

Offset

Shifts the LFO signal into the rectifier, controlling how much of each cycle drives the effect.
Negative: the effect only fires for part of the cycle, with silence in between.
Center: roughly half on, half silent.
Positive: the full cycle modulates continuously.

Bias

Shifts the resting position of the modulation.
In VCA: sets the attenuation floor. How much signal reduction is always present even between pulses.
In VCF: sets the base filter brightness when the LFO is at its quietest.

Wave

Triangle · Square · Saw ↑ · Saw ↓

Mode

VCA (amplitude) · VCF (filter)

Spread

Inter-channel LFO phase offset, creates a ping pong style stereo effect

Level

Output trim

Bypass

Bypasses the entire signal chain

Formats

AU · VST3 macOS 12+ / Universal
VST3 Windows 10/11 x64