The Warm Audio Bus-Comp is an all-analog, 2-channel, stereo bus compressor that uses four, THAT Corp 2180 VCA chips—two per channel. VCAs or Voltage Controlled Amplifiers provide the most accurate control of gain reduction.
Over the weeks since I got it, I tried it on everything! First up were entire stereo mixes in Pro Tools as sort of a “faux mastering” processor where the goal was loudness with minimal sonic damage. I was able to “pump it up” on average about 3 to 6dB without getting an overly squashed and smaller sound.
Later I tried it on a drum kit mixing bus that had all drum tracks included except the bass drum. It also sounded authentic when used lightly on acoustic guitars, keyboards, piano, and orchestral instruments.
Even though Bus-Comp is mainly for stereo use, I also tried one channel as a mono compressor on bass guitar. I liked its clean sound—even with massive gain reduction of up to 10dB. There is an “Engage Transformer” button that inserts two CineMag transformers into the signal path and, depending on the source audio, an overall rounding of the attacks happens plus a thickening of the lower mid-range.
Other controls are: Threshold, Attack Time, Ratio, Release Time (including Auto mode), and Make Up gain. An important feature is the selectable high-pass side-chain filter with six steps from Off to 185Hz. This HPF prevents low frequencies from driving the compression.
Warm Audio does it again with a low cost version of a classic VCA bus compressor. The Warm Audio Bus-Comp sells for $699.