Air-G Pulse

Air-G Pulse 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 respected free DSP algorithms in the audio world.

Pulse is a program compressor: it reacts to the average level of the signal over time, not to individual peaks. That makes it a glue tool, not a punch tool. What makes it unusual is that it has no attack or release controls: the response speed is built into the algorithm and changes dynamically based on signal level, so transients come through with their impact intact when the compressor is dialed in correctly.

Air-G adds a sidechain high-pass filter (SC HPF) to prevent kick or bass from dominating the detector, automatic gain compensation, and two VU meters showing gain reduction per channel independently.

The engine is Airwindows' Pressure6. COMPRESS adjusts the threshold and aggressiveness; PRESSURE determines how much of that processing, including integrated harmonic saturation on peaks, reaches the output. They work together but differently: COMPRESS defines where and how the compressor acts; PRESSURE sets the character of the result. With low PRESSURE and high COMPRESS, the effect is subtle and nearly transparent, useful for glue without obvious coloration. With both elevated, the compression is intense and the algorithm's grit defines the sound. Chris describes Pressure6's goal as a bus compressor that doesn't screw up the sound of your mix, one whose best version is the one where bypassing it makes the mix simply lose life.

Pulse is ideal on the 2-bus and group buses, especially drums, where the goal is glue, punch, and cohesion without sacrificing dynamic movement. It also works well on vocals and acoustic guitars, where the algorithm's dynamic response follows the phrasing naturally. There is also Air-G Pulse Mini, a version with the same audio engine in a compact rack module-style interface.

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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 Pulse 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.