G-Bus Compressor

Following the success of my first VST3 plugin, VLA-One, I decided to develop the next most useful plugin for mixing music: the bus compressor. The magic "glue" for any mix.

After some research and understanding the circuit, and with the help of AI (I did try to work out the algorithm myself, but not being an audio software engineer, I finally gave up), I was able to code a close simulation of an actual SSL 4000 compressor.

Testing and measuring my results against several commercial SSL 4000 plugins (Waves, IKMultimedia, Universal Audio) and tweaking my algorithm, I finally have a version that is very close and works for me.

G-Bus Compressor is an emulation of the legendary SSL 4000 G-Bus stereo bus compressor — the defining sound of countless hit records since the 1980s.

Like the original hardware, it uses a feedback topology where the detector reads the VCA output rather than the input, producing the natural self-regulating "glue" that the SSL console is famous for.

It features true stereo-linked RMS detection, discrete attack and release time selections, sidechain high-pass filtering, and a soft-knee gain computer that closely mirrors the behaviour of the original circuit.

The Drive control adds subtle output transformer saturation modelled on the SSL 4000 series output stage — a gentle second-harmonic warmth that adds density and presence without heavy colouration.

The plugin runs with 2x oversampling and a linear-phase filter around the saturation stage, keeping aliasing artefacts inaudible and preserving phase coherence for master bus use.

G-Bus Compressor is a FREE plugin. It doesn't require a license or any registration. Simply download (links below), copy the files into the VST3 folder of your system, re-scan your DAW for new plugins and use.

I would love to read your feedback, comments or any bugs or issues you may find.