O-Chorus User Guide
Lush, analog-inspired multi-voice BBD chorus
Getting Started
Quick Start
- Download the installer from your Ouaricon Audio account
- Run the installer — it installs both VST3 and AU formats automatically
- Open your DAW and scan for new plugins
- Insert O-Chorus on a track
- Enter your license key (OUA-XXXX-XXXX-XXXX) when prompted
System Requirements
| Platform | Details |
|---|---|
| macOS | macOS 10.13+ (Intel and Apple Silicon native) |
| Windows | Windows 10+ (64-bit) |
| RAM | 4 GB minimum, 8 GB recommended |
| Formats | VST3, AU |
| DAW | Any VST3/AU-compatible host |
Installation Paths
macOS:
- VST3:
~/Library/Audio/Plug-Ins/VST3/O-Chorus.vst3 - AU:
~/Library/Audio/Plug-Ins/Components/O-Chorus.component
Windows:
- VST3:
C:\Program Files\Common Files\VST3\O-Chorus.vst3
Interface Overview
O-Chorus features a compact, naturalist-styled interface with eight primary controls. An animated LFO ring at the center provides visual feedback of the modulation rate.
Layout
The interface presents all controls in a single row for quick, intuitive access:
- Rate & Depth: Core modulation controls for speed and intensity
- Voices & Spread: Voice count and delay-time distribution for thickness
- Width & Tone: Stereo imaging and high-frequency character
- Mix & Drive: Dry/wet blend and analog saturation amount
Knob Interaction
- Vertical drag: Click and drag up/down to adjust values
- Shift + drag: Fine-tune with smaller increments
- Double-click: Reset to default value
- Mouse wheel: Scroll to adjust (with gesture brackets)
All parameters can be automated in your DAW for dynamic chorus effects.
Parameters
| Parameter | Range | Default | Description |
|---|---|---|---|
| Rate | 0.05 - 5.0 Hz | 1.0 Hz | LFO modulation speed. Controls how fast the chorus voices sweep through their delay range. Lower values produce a slow, swaying motion; higher values create vibrato-like movement. |
| Depth | 0 - 100% | 50% | Modulation intensity. Sets how far the delay time swings around the center point. Higher depth produces a more pronounced pitch-shifting chorus effect. |
| Voices | 1 - 8 | 4 | Number of chorus voices. Each voice has its own LFO phase offset, creating a richer sound as more voices are added. One voice produces a simple chorus; eight voices create a dense ensemble. |
| Spread | 0 - 100% | 0% | Voice delay-time distribution across a 30ms range. At 0%, all voices share the same base delay. At 100%, voices are spread symmetrically across the delay range, making each voice more distinct. |
| Width | 0 - 100% | 70% | Stereo spread of the chorus voices. At 0%, all voices are centered (mono). At 100%, voices are panned across the full stereo field using equal-power panning. |
| Tone | -100% to +100% | 0% (center) | High-frequency character of the wet signal. Negative values roll off highs for a darker, more vintage BBD sound. Positive values brighten the chorus for added shimmer. |
| Mix | 0 - 100% | 50% | Dry/wet blend. At 0%, only the dry signal is heard. At 100%, only the chorus voices are heard (useful for vibrato effects). 50% provides the classic chorus blend. |
| Drive | 0 - 100% | 30% | Analog saturation amount. Applies tanh soft-clipping with subtle asymmetry to emulate the harmonic warmth of vintage BBD chips. Higher values add grit and presence. |
Parameter Details
Rate
The Rate control uses a skewed range (0.05 - 5.0 Hz) that gives more resolution in the lower, musically useful range. Most classic chorus effects live between 0.3 - 1.5 Hz. Rates above 3 Hz enter vibrato territory.
Voices & Spread
These two parameters work together to determine the thickness of the chorus effect. Increasing Voices adds more modulated delay lines, each with a unique LFO phase offset. The Spread control then distributes these voices across different base delay times, preventing them from stacking on top of each other. For the richest sound, try 6-8 voices with 50-80% spread.
Tone
The Tone control applies a one-pole filter to the wet signal, sweeping between 2kHz (fully dark) and 20kHz (fully bright), with a center point around 8kHz. Classic BBD chorus units naturally rolled off high frequencies due to the analog bucket-brigade circuit — pull Tone toward the dark side to recreate that character.
Drive
Drive applies tanh saturation with subtle asymmetry to emulate the nonlinear behavior of BBD chips. Even at low settings, it adds harmonic richness that helps the chorus sit in a mix. At higher settings, it introduces audible warmth and compression.
Presets
O-Chorus includes 6 factory presets covering a range of chorus applications:
| Preset | Description |
|---|---|
| Classic | Vintage 2-voice chorus with subtle modulation (0.5 Hz) — a great starting point for guitars and keys |
| Lush | Rich 6-voice ensemble with slow, deep modulation and wide stereo spread — for pads and ambient textures |
| Shimmer | Bright, sparkling 4-voice chorus at 2 Hz with boosted tone — adds air and movement to clean signals |
| Ensemble | Dense 8-voice string ensemble with full spread and width — the thickest, most immersive setting |
| Vibrato | Pure vibrato effect using a single voice at 3 Hz, 100% wet — classic pitch modulation without dry signal |
| Warm | Warm analog-style 3-voice chorus with dark tone and high drive — emulates vintage BBD hardware |
Managing Presets
Use the preset navigation controls at the top of the interface to browse, save, and load presets:
- Arrow buttons: Step through presets sequentially
- Dropdown menu: Jump to any preset by name
- Save: Save the current settings as a user preset
- Load: Load a previously saved preset file
Presets are stored at:
macOS: ~/Library/O-Chorus/Presets/
You can create custom presets and share them by copying preset files to this directory.
Creative Uses
Classic Guitar Chorus
Start with the Classic preset. Keep Voices at 2-3, Rate around 0.5 Hz, and Depth at 30-40%. Pull Tone slightly dark for a vintage Boss CE-1 character.
Thick Synth Ensemble
Use the Ensemble preset as a starting point. 8 voices with full spread creates the dense, shimmering sound heard in classic string machines and polysynths like the Roland Juno-60.
Subtle Stereo Widening
Set Mix to 20-30%, Voices to 4-6, and Spread to 50%. This adds gentle stereo width without an obvious chorus effect — useful on vocals, acoustic instruments, or buses.
Lo-Fi Vibrato
Load the Vibrato preset. With Mix at 100% and a single voice, the plugin acts as a pitch vibrato. Increase Drive to add analog warmth for a worn-tape character.
Troubleshooting
Plugin Not Appearing in DAW
- Rescan your plugin directories in your DAW's preferences
- Verify the plugin is installed at the correct path (see Installation Paths above)
- On macOS, check that Gatekeeper hasn't blocked the plugin (System Settings → Security & Privacy)
- Restart your DAW after installation
No Chorus Effect Audible
- Check that Mix is greater than 0%
- Check that Depth is greater than 0%
- Verify audio is passing through your track (check DAW meters)
- Try the Lush preset to verify the effect is working
More Voices Don't Sound Different
- Increase the Spread parameter — at 0%, all voices share the same base delay time and sound similar regardless of count
- Increase Width to pan voices across the stereo field
- Try the Ensemble preset (8 voices, full spread) for the most obvious difference
License Activation Issues
- Check your internet connection
- Verify the license key format is correct:
OUA-XXXX-XXXX-XXXX - Ensure you haven't exceeded the 3-machine activation limit
- Contact [email protected] if problems persist
High CPU Usage
- O-Chorus is optimized and should use minimal CPU, even with 8 voices
- If you experience high CPU, try reducing the voice count or check your DAW's buffer size settings
- Close other resource-intensive plugins on the same track