Welcome back to Compression Explained. In the past two editions, we’ve covered how to think about compression and how to shape sounds with attack, release, threshold, ratio, and knee. Today, we’re taking it one step further by looking at the different types of compressors you’ll encounter in your sessions. Each design has its own behaviour, character, and “flavour”. Knowing which to reach for can make a big difference in your mixes and masters.
FET Compressors
Fast, punchy, and colourful.
Field Effect Transistor (FET) compressors, like the classic 1176, are known for their aggressive and musical character. They react quickly, making them great for adding punch to drums, vocals, or bass. If you need energy and excitement, FET is usually the way to go.
VCA Compressors
Clean and versatile.
Voltage Controlled Amplifier (VCA) compressors, such as the SSL bus compressor, are precise and transparent. They excel at glueing a mix together without adding too much colour. With their wide control range, VCAs are popular on mix buses and for mastering when you need control without losing clarity.
Optical Compressors
Smooth and musical.
Optical compressors, like the LA2A, use a light source and a light-dependent resistor to control gain reduction. The result is a naturally smooth response, perfect for vocals and instruments that need gentle, musical compression. Think of them as “set and forget” tools – they’re not lightning-fast, but they add warmth and vibe.
Variable-Mu Compressors
Rich and gluey.
These tube-based designs, like the Fairchild 670, are all about character. They compress by varying the bias of tubes, which adds a warm, harmonically rich sound. They’re slower than FET or VCA designs, but perfect for adding cohesion, depth, and a luxurious “finished” feel to a mix or master.
So Which Style Should You Use?
It depends on the goal. If you need aggressive punch, grab a FET. For precise control, reach for a VCA. When you want smoothness and vibe, an Optical works wonders. And if you’re chasing warmth and glue, Variable-Mu might be your best friend.
The trick is to match the compressor’s natural character to the needs of the song. Over time, you’ll instinctively know which tool to pull up.
Want to learn more about compression? Join us tomorrow, Thursday, September 25th, at 10:00am ET (4:00pm CEST) for demonstrations teaching you expert-level compression techniques during the educational launch event of our first ever plugin. Make sure to register in time for the event as it’s only 24 hours away!
See you tomorrow,
Rob
