HARMONICO dsp has released Airy, a free stereo widening plugin for macOS and Windows.
Airy was developed by Nicolas Barreau, a sound engineer and acoustician based in Paris. He reached out via email and described the plugin as a “point source widener,” inspired by the Airy diffraction pattern, in which a single point of light passing through a lens becomes a bright core with faint surrounding haloes.
That sounds a bit abstract and took me a minute to figure out what the plugin is about, but the idea is actually simple enough. Airy measures the width your signal already has in different frequency bands, then adds only the missing width needed to reach the target you draw on its stereo field map.
The thing I don’t like about stereo wideners is that they can be risky when they rely too much on phase tricks, especially if you care about mono compatibility. Airy’s key promise is that it only touches the Side channel, so the mono sum stays intact at any width setting. The PERCEPTUAL engine is also zero-latency.
The interface includes a stereo field map where you paint the target width directly. The display shows your signal’s energy across frequency, and the contour you draw becomes the width target the engine tries to reach.
The cool part is that if part of the signal is already wide enough, Airy is designed to leave it alone instead of blindly pushing everything wider.
Airy can also synthesize Side content from a mono signal using its GENERATE control, which makes it useful for mono-to-stereo work as well as widening narrow stereo sources. The developer notes that mono-to-stereo inserts are supported in Pro Tools.
Other useful controls include DIFFUSION, which changes the character of the added width from focused to airy, and MONO BELOW, which keeps the low end centered with elliptical bass-mono processing. That is something I use a lot in my sound design work.
CORR POS keeps the left/right correlation at or above zero for a more vinyl- and broadcast-safe range, while RIDE lets the width follow the program signal or an external sidechain.
There are also two assignable LFOs with transport-locked sync, randomization with locks, A/B comparison, and two visual themes called LASER and ARGENT. Airy includes the default PERCEPTUAL engine and a second SPECTRAL engine for a more diffracted texture, although it uses FFT latency.
I also asked Nicolas whether the plugins were AI-generated, and he clarified that the concepts, DSP architecture, parameter tuning, measurement, and listening work are his. He said he uses AI coding assistants as part of a C++/JUCE workflow, but mainly for implementation, refactoring, and test harnesses.
Airy is free, with no activation and no account required. You do need to enter an email address to receive the download link.
Airy is available in VST3, AU, and AAX formats. It supports macOS 10.15 or later (Intel and Apple Silicon) and Windows 10/11 64-bit, with AAX support for Pro Tools 2023 or later.
Download: HARMONICO dsp Airy (FREE)
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Last Updated on August 19, 2026 by Tomislav Zlatic.
