VCA, FET, optical and tube compressors compared
Answer in brief
The four names come from the hardware circuits that set how gain moves. VCA is clean and controlled, FET is fast and aggressive, optical is smooth and slow, and tube (variable-mu) is gentle and thick.
VCA compressors
A VCA compressor uses a voltage-controlled amplifier and follows the settings closely. It suits drum buses and the mix bus because it can be precise without adding much color. The console bus compressor that Cytomic The Glue is modeled on is a well-known VCA design.
FET compressors
A FET compressor uses a transistor to change gain and can react very fast. It is the classic choice for catching vocal peaks and making drums bite. The 1176 is the best-known example, and Universal Audio describes its original as a breakthrough in fast FET gain reduction.
Optical compressors
An optical compressor uses a light and a light-sensitive cell. The cell responds a little slowly and lets go in stages, so the result sounds smooth even when it works hard. It is a common pick for vocals and bass that need steady level without obvious pumping.
Tube or variable-mu compressors
A variable-mu compressor changes gain inside a tube, so the ratio rises as the sound gets louder. It sounds soft and thick and is often used lightly on a full mix. Klanghelm’s MJUC jr is a free compressor in this family.
Digital designs with no hardware behind them
Some compressors make no attempt to copy a circuit. Tokyo Dawn Records describes TDR Kotelnikov as proudly digital, aimed at control that stays out of the way. These suit jobs where you want level control without color.
Sources for this page
- Studio 56: Studio 56’s official website, the publisher of this reference.
- Cytomic The Glue: Cytomic The Glue’s official page, the source of its description here.
- TDR Kotelnikov: TDR Kotelnikov’s official page, the source of its description here.
The practical advice here is our own. A maker's description of its product is not a test of how it performs.
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Cite this page
Best Compressor Plugin. “VCA, FET, optical and tube compressors compared.” Studio 56 Reference. Content reviewed November 8, 2026.
https://bestcompressorplugin.com/compressor-types/