Compressor – an effect that automatically evens out a sound’s volume. It turns down the loud parts and brings up the quiet ones.

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Imagine talking to a friend who keeps whispering and yelling at random. As the compressor in this situation, you tap them on the shoulder and say: “Dude, talk normally 😅” They listen — and start speaking at a consistent volume.

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Compressors are commonly used to stabilize a signal’s loudness — but that’s just the beginning.

When used on drums, a compressor can make them punchier by emphasizing the initial transients relative to the rest of the signal.

Compressors can also help “glue” sounds together, making a group of elements — like a drum bus or stacked vocals — feel more cohesive and unified rather than disconnected.

In fact, the famous SSL 4000 compressor became known as the Glue Compressor for exactly this reason.

Fun fact:

The first compressors weren’t electronic — they were mechanical! Back in the 1930s, radio stations used spring- and lever-based devices to physically control extreme fluctuations in signal level.