Duono Free Mono-to-Stereo Widener Plugin by Stefano Baldan
Stefano Baldan’s Duono is a free mono-to-stereo widener plugin for Windows and macOS. It processes organic, multi-frequency material such as bowed strings, whistles, harps, double bass, voices, and lush pads with a single control, expanding mono sources into a fuller stereo image without artifacts.
The plugin is available as a “pay what you like” download from Baldan’s site, with the base price set to zero. No sign-up is required to download the installer, and the license is royalty-free for use in any project.
Duono runs as a VST3, Audio Unit, and CLAP plugin on macOS (Intel/Apple Silicon) and Windows (x64). The installer package weighs under 1 MB and supports drag-and-drop installation into most DAWs.
Key features
- Single-knob mono-to-stereo widening
- Optimized for harmonic-rich, organic sources
- Ultra-lightweight (<1 MB)
- Cross-platform: VST3, AU, CLAP
- Royalty-free license included
- No account or watermarking
Supported platforms
- macOS 12+
- Windows 10/11 (64-bit)
Intended use cases
- String sections and solo bowed instruments
- Vocal doubling and panning
- Harp, whistle, and breathy textures
- Lush pads and ambient layers
- Double bass and upright bass widening
Download the installer directly from Stefano Baldan’s site and drop it into your session. The plugin loads instantly and adds width without smearing transients or introducing phasing issues.
Quick Facts: Duono is a free mono-to-stereo widener plugin from sound synthesis researcher Stefano Baldan. It’s royalty-free, requires no sign-up, and supports VST3, AU, and CLAP on macOS and Windows.