Air-G Prism

Air-G Prism is part of Air-G Audio, a collection of plugins built on the open source work of Airwindows, Chris Johnson's project that has been releasing some of the most precisely crafted free DSP algorithms in the audio world.

Prism is a six-band graphic equalizer with fixed frequencies: SUB, BASS, LMID, MID, HMID, and HIGH. Each band has a single gain control and can be switched on or off independently. There are no frequency or Q knobs, because the fixed design is intentional, the way a classic hardware graphic EQ works. An interactive display draws the real frequency response and lets you drag each band's node directly with the mouse.

The engine is Airwindows' PearEQ, and its approach is different from a conventional digital EQ. The bands are built subtractively: it separates the spectrum by removing low-pass filters from the signal in sequence, working down from the top. The result is that all bands sum to perfectly flat at zero, so the plugin is literally transparent at rest. The bands are steep and well-isolated from each other, but without generating resonant peaks, so even large moves sound musical. The SUB band covers the octave below the bass, everything below roughly 40 Hz, with enough isolation to control it without affecting the rest of the spectrum.

Prism is ideal for shaping the spectrum broadly and with authority: cleaning mud from the low-mids, controlling sub-bass on the master bus, opening the highs without touching presence. For surgical corrections at a specific frequency there are better tools. For bus voicing, mastering, and general spectral shaping, Prism carries real weight.

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Air-G Audio is a collection of plugins built on the open source code of Airwindows. The project is built around adding a graphical interface that makes the experience more comfortable and visual, along with a few features that expand the possible uses without straying from the original sound. The simplicity and lightness of Chris's code are the starting point and the guide.

Thanks to Chris Johnson for making his work public and accessible. Air-G Audio exists because Airwindows exists. The Airwindows code used in this plugin is published under the MIT License.

Air-G Prism is free. You can download it without paying anything, following the same open philosophy that runs through all of Chris's work. If the plugin is useful to you in your music, a contribution is always welcome. Chris Johnson's Patreon is also worth knowing about: it's the most direct way to support the Airwindows project and the work that makes plugins like this one possible. patreon.com/airwindows.

Available for Windows, Linux and macOS.

*New: Windows & Linux — All VST3, no installer download

***Windows note: the installer is not signed with a paid certificate, so SmartScreen may show a "Windows protected your PC" warning. Click "More info", then "Run anyway" to continue. This is expected and not a problem with the plugin.

***macOS note: the plugin is not signed with an Apple developer certificate, so Gatekeeper may block it on first use. The "Open Anyway" option in System Settings does not work reliably for audio plugins. The correct fix requires Terminal:
1. Open Terminal (Applications > Utilities > Terminal).
2. Type: sudo xattr -rd com.apple.quarantine (leave a space at the end, do not press Enter yet).
3. Open Finder and navigate to your plug-in folder: VST3 plugins are in /Library/Audio/Plug-Ins/VST3/, and AU plugins (for Logic and GarageBand) are in /Library/Audio/Plug-Ins/Components/. Drag the plugin file (the .vst3 or the .component) into the Terminal window. The path fills in automatically.
4. Press Enter and type your admin password when prompted (it will not be visible). Press Enter again.
5. Rescan your plugins in your DAW. The plugin should now appear. If you installed both the VST3 and the AU versions, repeat the process for each file.