User Guide

Installation & Formats

Impulse Cycler v1.0.0 is a free audio effect plugin. It ships as AU and VST3 on macOS, and as VST3 on Windows and Linux.

Quick Start

Get up and running with Impulse Cycler in five steps:

1. Load Impulse Cycler as an audio effect on a drum or percussive track
2. Adjust Attack to boost or soften transients
3. Adjust Sustain to extend or shorten the body
4. Optionally enable a synth engine and raise Level to layer synthetic transients
5. Enable motion on supported parameters for tempo-synced modulation

What Impulse Cycler Does

Impulse Cycler transforms static transient shaping into a dynamic, performable effect. The core TransientCore technology uses dual envelope followers to detect and shape transients without requiring threshold settings — it works consistently on both quiet and loud material. Layer synthetic transients from 7 different engines, then add cyclical motion to supported parameters for continuously evolving textures.

Typical Use Cases

• Drum enhancement — Add punch and snap to kicks, snares, and toms
• Transient softening — Tame harsh attacks on percussion
• Synthetic layering — Add clicks, pings, or noise bursts to drum hits
• Evolving textures — Motion-modulated parameters create rhythmic variation
• Sound design — Transform percussive sources into evolving timbres

Signal Flow

Audio flows through four main stages. The motion system can modulate parameters at any stage, with modulation depth scaled by an envelope follower that responds to input dynamics.

                           IMPULSE CYCLER
       ┌──────────────────────────────────────────────────────────────┐
       │                                                              │
       │   ┌──────────────┐    ┌──────────────┐    ┌───────────┐      │
Input ▶│   │ TransientCore│───▶│    Body      │───▶│  Output   │     ▶│ Output
       │   │              │    │  Processing  │    │   Stage   │      │
       │   │ Attack       │    │              │    │           │      │
       │   │ Sustain      │    │ Gain, Tilt   │    │ Mix, Gain │      │
       │   │              │    │ Damping      │    │           │      │
       │   └──────┬───────┘    └──────────────┘    └─────┬─────┘      │
       │          │                                      │            │
       │          │ onset                                │            │
       │          ▼                                      │            │
       │   ┌──────────────┐                              │            │
       │   │   Synth      │──────────────────────────────┘            │
       │   │   Layer      │                                           │
       │   │              │                                           │
       │   │ 7 Engines    │                                           │
       │   └──────────────┘                                           │
       │          ▲                                                   │
       │          │                                                   │
       │   ┌──────┴───────┐                                           │
       │   │   Motion     │◀── Envelope Follower (scales depth)       │
       │   │   LFOs       │                                           │
       │   └──────────────┘                                           │
       └──────────────────────────────────────────────────────────────┘

The envelope follower tracks input dynamics and scales LFO modulation depths above a baseline motion floor:

• Loud input: High envelope → full motion depth
• Quiet input: Low envelope → subtler baseline motion

GUI Overview

Impulse Cycler's interface is organized into three main columns. Understanding the layout helps you navigate quickly.

TransientCore

TransientCore is the foundation of Impulse Cycler. It uses dual envelope followers (fast and slow) to detect and shape transients without requiring threshold settings. This level-independent approach works consistently on both quiet and loud material.

Attack & Sustain

Attack (-15 to +15 dB)

Controls the transient attack portion of the signal:

• Positive values: Boost transients for more punch and snap
• Negative values: Soften transients for smoother attacks
• 0 dB: No change to attack

Sustain (-24 to +24 dB)

Controls the sustain/body portion of the signal:

• Positive values: Extend and boost the sustain phase
• Negative values: Shorten and reduce the sustain
• 0 dB: No change to sustain

Body Processing (Refine)

Extended processing for the shaped signal, found in the "refine" section below the main knobs.

Body Gain (-24 to +12 dB)

Additional level control for the body of the signal, applied after TransientCore shaping.

Body Tilt (-12 to +12 dB)

Spectral tilt control:

• Positive values: Boost high frequencies, brighter body
• Negative values: Boost low frequencies, darker body

Damping (0-100%)

Progressive high-frequency absorption. Higher values apply more high-frequency damping over time, useful for creating warmer, more natural-sounding sustains.

Synth Layer (Resynthesis)

The synthesis layer generates synthetic transients triggered by detected onsets. This allows you to layer additional character on top of the shaped signal.

Global Synth Controls

Level (-60 to +12 dB)

Output level of the synth layer. At -60 dB (minimum), the synth is effectively off. Raise this to blend synthetic transients with your shaped signal.

Decay (0.1-1.0)

Envelope decay rate for most synth engines. Higher values produce longer tails; lower values create shorter, punchier transients. The Impulse engine is also strongly shaped by its Resonance control.

Engine-Specific Parameters

Each engine exposes context-specific controls. Most engines use Param A and Param B; Noise uses a single Duration control.

Synth Engines

Impulse Cycler includes 7 synthesis engines, each creating a different type of synthetic transient.

Engine Cycling

Engine cycling automatically changes the synth engine on each transient trigger, creating variation across hits.

Cycle Modes

Cycle Hold

Controls how many triggers before changing to the next engine:

• 1: Change engine on every trigger
• 2: Change every 2 triggers
• 4: Change every 4 triggers
• 8: Change every 8 triggers

Motion System

The motion system adds tempo-synced LFO modulation to parameters, creating continuously evolving textures. Motion depth is scaled by an envelope follower that responds to input dynamics — modulation becomes more pronounced during loud sections while quieter passages retain a subtler baseline motion.

Modulatable Parameters

9 parameters can have motion applied:

1. Attack (TransientCore)
2. Sustain (TransientCore)
3. Body Gain (Refine)
4. Body Tilt (Refine)
5. Damping (Refine)
6. Synth Level
7. Synth Decay
8. Engine Param A (context-dependent)
9. Engine Param B (context-dependent)

Motion Parameters

Each modulatable parameter has four motion controls:

Enable (On/Off)

Toggle motion modulation for this parameter.

Rate (Tempo-synced)

LFO cycle speed, synced to host tempo when the host provides BPM. If no host tempo is available, Impulse Cycler uses 120 BPM as a fallback:

• 4 bars — Slowest, subtle long-term movement
• 2 bars, 1 bar — Medium sweeps
• 1/2, 1/4 — Quarter/half note cycles
• 1/8, 1/16, 1/32 — Faster rhythmic motion
• Triplets (1/4T, 1/8T, 1/16T) — Triplet divisions
• Dotted (1/4D, 1/8D) — Dotted note divisions

Depth (0-100%)

Maximum modulation amount. This is scaled by the envelope follower output and the built-in baseline motion floor, so actual depth varies with input dynamics without disappearing completely on quieter material.

Shape

LFO waveform:

• Sine — Smooth, organic motion
• Triangle — Linear, symmetrical sweeps
• Saw — Rising ramp with instant reset
• Square — Alternating between extremes
• S&H — Random sample-and-hold steps

Envelope Follower (ENV)

The envelope follower tracks input dynamics and controls how strongly motion responds to the source. This creates dynamics-responsive modulation — motion is more pronounced during loud passages and subtler during quiet ones.

Sensitivity (0-100%)

How much input level lifts motion above the baseline floor:

• 0%: Motion uses the steady baseline amount set by each lane's Depth
• 100%: Motion responds most strongly to input dynamics

Attack (1-100 ms)

How quickly the envelope responds to transients. Lower values react faster to hits.

Release (10-500 ms)

How quickly the envelope falls after transients. Longer releases create more sustained motion.

Presets

Factory Presets

Impulse Cycler includes factory presets as starting points:

User Presets

Save your own configurations using the Library system in the plugin header. The preset dropdown groups factory and user presets, Save prompts for a preset name, and Load opens an .impulse-cycler preset file from disk.

Preset Storage Location:

• macOS: ~/Library/Application Support/Aftertone & Signal/Impulse Cycler/Presets/
• Windows: %APPDATA%/Aftertone & Signal/Impulse Cycler/Presets/
• Linux: ~/.config/aftertone-and-signal/impulse-cycler/presets/

Output Controls

Mix (0-100%)

Dry/wet blend between the original signal and the processed signal:

• 0%: Fully dry (original signal only)
• 100%: Fully wet (processed signal only)

Output Gain (-12 to +12 dB)

Final output level adjustment. Use this to match levels with the bypassed signal.

Tips & Techniques

Parameter Reference

TransientCore Parameters

Body Processing Parameters

Synth Parameters

Engine-Specific Parameters

Output Parameters

Envelope Follower Parameters

Motion Parameters (per modulatable parameter)

Impulse Cycler v1.0.0
Aftertone & Signal
aftertone.co