GRIZZLYAOFN

Input → Drive → JFET model → Output

Audio enters and passes through the Drive stage first — a model of the original circuit's op-amp amplifier that adds warmth and harmonic weight before the modulator sees it. This is not just a level control; the character of the saturation interacts with the modulation that follows.

The signal then enters a JFET-modelled stage controlled by the LFO. Depending on Mode, that stage either controls the amplitude of the signal (VCA) or the cutoff of a lowpass filter placed across it (VCF). Depth, Offset, and Bias shape how fully and at what position in each cycle the effect fires.

After the modulator, Spread offsets the left and right LFO channels independently, and Level trims the final output before it leaves the plugin.

From a slow crawl to audio-rate

Speed sets the LFO frequency from 0.01 Hz to 30 Hz. Below 1 Hz you get slow, breathing movements. Around 4–8 Hz is classic tremolo territory. Push past 20 Hz and the modulation enters audio range, producing ringmod-adjacent tones that interact with the incoming pitch in unexpected ways.

Lock to host tempo

When Sync is engaged, Speed switches to note divisions tied to the host transport. Seventeen values are available: from 8 bars per cycle down to 1/32, covering straight, dotted, and triplet note values. The LFO phase resets on transport start. If your host does not export tempo information, Sync falls back to the free-running Speed value.

Four shapes, four characters

• Triangle Smooth rise and fall. Classic tremolo shape. Shape controls slope symmetry.
• Square Hard on/off switching. Gating, choppy pulses. Shape controls duty cycle.
• Saw ↑ Gradual build, instant drop. A tension-and-release pattern.
• Saw ↓ Instant attack, gradual fade. Shape has no effect on either saw wave.

Change the contour of each cycle

Shape's behaviour depends on the selected wave. For Triangle, it controls slope asymmetry: at minimum, a fast-rise ramp; at centre, a symmetric V; at maximum, a fast-fall ramp. For Square, it controls duty cycle — how long the wave stays high versus low. Shape has no effect on either Saw wave.

VCA or VCF — two effects from the same LFO

VCA uses the LFO to control the amplitude of the signal. This gives you tremolo, rhythmic gating, choppy 8th-note pumping, slow breathing swells, and at high speeds, ringmod-adjacent tones.

VCF uses the LFO to open and close a lowpass filter across the signal. This gives you autowah, dub-wise cutoff pulses, slow filter sweeps, and the kind of muted-then-open motion that usually requires a wah pedal and a foot.

How far the LFO moves the effect

Depth controls the intensity of the modulation. At low values the effect is subtle — a gentle wobble or slight filter movement. At maximum the LFO swings the full range of the JFET stage. Stack Depth with Offset and Bias to dial in exactly how far the effect travels within each cycle.

How much of each cycle fires the effect

Offset shifts the LFO signal into the rectifier that gates the JFET stage. This controls what fraction of each cycle actually drives the modulation.

• Minimum The effect fires for only a short burst each cycle, with near-silence between
• Centre Roughly half the cycle modulates, half is silent
• Maximum The full cycle modulates continuously

Pulling Offset back while using a slow speed is the fastest way to get the Gristleizer's characteristic rhythmic stutter.

The resting position of the modulation

Bias shifts the baseline of the effect. Its meaning differs by mode.

• VCA Sets the attenuation floor — how much signal reduction is always present, even between pulses
• VCF Sets the base filter brightness when the LFO is at its quietest

Pre-gain into the modulator

Drive is a model of the original circuit's op-amp stage. It runs from −12 dB to +24 dB and shapes the signal before it enters the JFET model. At low settings it acts as a pad. At unity it passes cleanly. Push it above about +6 dB and it adds warmth and harmonic texture that interacts with the modulation depth and the character of the JFET response.

Because Drive hits before the modulator, it affects the tone of every pulse and filter sweep rather than just the output level. On transient sources like drums this distinction is audible.

Tie Level to Drive

The Link toggle sits next to the Drive knob. When on, Level tracks Drive automatically, pushing Drive up brings Level down by a corresponding amount, and pulling Drive back raises Level to compensate. This keeps the perceived output loudness stable as you dial in Drive character, so you can focus on the tonal effect rather than chasing the volume.

Turn Link off to set Drive and Level independently. Level then acts as a plain output trim with no relationship to Drive.

Offset left and right LFO channels

Spread introduces a phase offset between the LFO driving the left channel and the one driving the right. At zero both channels move together. As you increase Spread the two channels start moving out of step, widening the stereo image.

At maximum the channels are fully out of phase — when the left channel is at the peak of a tremolo pulse, the right is at the trough. Combined with a fast square wave this becomes an aggressive ping-pong gate.

Output trim after the modulator

Level is an output trim that sits after the entire signal chain. Use it to compensate for the loudness change that large amounts of Drive or deep modulation can introduce, or to match the bypassed and active level before committing to a sound.

When Link is on, Level is coupled to Drive and adjusts automatically as Drive changes. See 04.2 — Link.

Removes the entire signal chain

Bypass passes the input through to the output untouched — Drive, modulation, and Level are all removed from the path. Use it for A/B comparisons or to drop the plugin in as a placeholder and enable it later.

• macOS 12 Monterey or later · Apple Silicon + Intel
• Windows 10 / 11 · 64-bit
• Linux 64-bit · ARM (experimental)
• Formats AU · VST3
• Hosts Any AU or VST3 compatible host
• Price Free

• Engineering Marcel Haupt · AOFN Audio
• Contact grizzly@anoldfrenchname.com