Tube compressor
A tube compressor is a compressor that utilizes vacuum tubes to apply gain reduction. Other compressor types, such as an optical compressor, may utilize vacuum tubes, but will not use them for gain reduction. The amount of gain reduction is based on the input. Due to this, they are also called “variable-mu compressors”, as the Greek letter mu () is used to represent voltage of a vacuum tube. However, this name is actually trademarked by Manley.
Famous tube compressors are…
Fairchild 670
- The 660 (the mono version) was used for the drums on the Beatles’ Sergeant Peppers Lonely Hearts and Revolver.
- Doesn’t have “ratio”, “attack”, “release” knobs
- Fairly quick attack and a fairly slow release
- Great on vocal tracks and vocal buses, and other “light” instrument mix groups (keyboards, horns…)
- Not good at containing modern bass transients (since these frequencies are lower than what was typical back when the 670 was built)
Manley Variable Mu
- No ratio knob
- Described as “very transparent” and as “glue”
- Not punchy
Notable plugins
Fairchild 670:
Variable Mu: