JC-303
Unlock the iconic sound of Roland's TB-303 with JC-303, a faithful emulation of the legendary acid house and techno synth, available free of charge as a VST2, VST3, LV2, CLAP, and AU plugin for Linux, macOS, or Windows DAWs.
Key Features
- Authentic TB-303 sound engine — based on Open303, over 15 years of community reverse engineering and development
- AI Overdrive section — GuitarML-driven pedal and cabinet emulations using machine learning models
- Devilfish-inspired mods — select parameters from Robin Whittle's legendary 1993 modification
- Open-source — all DSP and GUI source code freely available under GPLv3
- Cross-platform — Windows, macOS, and Linux
- Plugin versatility — VST2, VST3, LV2, CLAP, and Audio Unit formats
Download
| Platform | Architecture | Link |
|---|---|---|
| Windows | Intel x64 | jc303-windows_x64-plugins.zip |
| macOS | Universal (Intel + ARM) | jc303-macos_universal-plugins.zip |
| Linux | Intel x64 | jc303-linux_x64-plugins.zip |
| Linux | ARM64 | Coming soon |
Installation
Each platform ZIP contains folders per plugin format. Copy the desired format(s) to your system's standard plugin directory.
Windows
| Format | Default Path |
|---|---|
| VST2 (.dll) | C:\Program Files\VSTPlugins or C:\Program Files\Steinberg\VSTPlugins |
| VST3 (.vst3) | C:\Program Files\Common Files\VST3 |
| CLAP (.clap) | C:\Program Files\Common Files\CLAP |
| LV2 (.lv2) | %APPDATA%\LV2 or C:\Program Files\Common Files\LV2 |
macOS
| Format | Default Path |
|---|---|
| Audio Unit (.component) | /Library/Audio/Plug-Ins/Components |
| VST2 (.vst) | /Library/Audio/Plug-Ins/VST |
| VST3 (.vst3) | /Library/Audio/Plug-Ins/VST3 |
| CLAP (.clap) | /Library/Audio/Plug-Ins/CLAP |
| LV2 (.lv2) | /Library/Audio/Plug-Ins/LV2 |
macOS De-Quarantine
macOS Gatekeeper blocks unsigned plugins. De-quarantine after copying:
# Audio Unit
sudo xattr -rd com.apple.quarantine /Library/Audio/Plug-Ins/Components/JC303.component
# VST3
sudo xattr -rd com.apple.quarantine /Library/Audio/Plug-Ins/VST3/JC303.vst3
# VST2
sudo xattr -rd com.apple.quarantine /Library/Audio/Plug-Ins/VST/JC303.vst
# CLAP
sudo xattr -rd com.apple.quarantine /Library/Audio/Plug-Ins/CLAP/JC303.clap
# LV2
sudo xattr -rd com.apple.quarantine /Library/Audio/Plug-Ins/LV2/JC303.lv2
Linux
| Format | Default Path |
|---|---|
| VST2 (.so) | ~/.vst, /usr/lib/vst |
| VST3 (.vst3) | ~/.vst3, /usr/lib/vst3 |
| LV2 (.lv2) | ~/.lv2, /usr/lib/lv2 |
| CLAP (.clap) | ~/.clap, /usr/lib/clap |
After copying, rescan plugins in your DAW.
Sound Engine
The JC-303 synthesis core is based on Open303, an open-source digital emulation of the TB-303 that began in 2009 when Robin Schmidt posted a call for collaborators on the KVR Audio forum.
Over 15 years, a community of TB-303 enthusiasts dove into oscilloscope measurements, circuit reverse engineering, and deep analysis of the original hardware's quirks and character. The result is one of the most accurate open-source TB-303 emulations available.
AI Overdrive Section
JC-303 integrates GuitarML technology, which uses machine learning to capture the sound of real overdrive pedals and guitar cabinets. The trained models recreate the response of actual analog hardware in real time.
- Community-driven project with a growing library of models
- Sheer unlimited tonal possibilities beyond the original TB-303
Devilfish-Inspired Mods
Created by Robin Whittle in 1993, the Devil Fish modification is one of the most sought-after third-party modifications of the original TB-303. JC-303 brings select Devil Fish parameters into the plugin, expanding the sonic palette beyond the stock 303 architecture.
Plugin Formats
| Format | Windows | macOS | Linux |
|---|---|---|---|
| VST2 | ✅ (self-build) | ✅ (self-build) | ✅ (self-build) |
| VST3 | ✅ | ✅ | ✅ |
| LV2 | ✅ | ✅ | ✅ |
| CLAP | ✅ | ✅ | ✅ |
| Audio Unit | — | ✅ | — |
VST2 binaries require a Steinberg VST2 SDK license and must be compiled from source.
Building from Source
JC-303 uses CMake and JUCE. Clone the repository and generate build files for your platform.
Dependencies
Ubuntu / Debian:
sudo apt install build-essential gcc cmake libx11-dev libxrandr-dev libxinerama-dev libxcursor-dev libfreetype6-dev libasound2-dev
macOS: Xcode command line tools
Windows: Visual Studio 2022
Generate Build Files
git clone https://github.com/midilab/jc303.git
cd jc303
macOS (Universal binary):
cmake -B build -G Xcode -D CMAKE_OSX_ARCHITECTURES="arm64;x86_64" -D CMAKE_OSX_DEPLOYMENT_TARGET=10.13
Windows:
cmake -B build -G "Visual Studio 17" -A x64
Linux:
cmake -B build
Compile
cmake --build build --config Release
GUI Themes
Choose a theme at CMake configuration time:
cmake -B build -D GUI=midilab
Available themes: amadeusp (default), midilab
VST2
Copy the vstsdk2.4/ folder to the project root before running CMake to enable VST2 builds.
Roadmap
- ✅ Binary releases for macOS, Windows, Linux
- ✅ Graphical user interface
- ✅ Internal engine tuning parameters (Devilfish inspired)
- ✅ Overdrive section
- 🔄 Preset support
- 🔄 Step sequencer
Community
JC-303 is a community-driven project open to contributions in coding, testing, bug reporting, design, and ideas.
License
JC-303 is released under the GNU General Public License v3. The Open303 engine portion is additionally licensed under the MIT License.
Roland and TB-303 are registered trademarks of Roland Corporation. JC-303 is not affiliated with or endorsed by Roland Corporation.