In this series of videos, we look at what compressors do and why they are used. Then we put some sounds through one and see what effect it has.
Part 1
Part 2
How To Use One
In this video, we look at how to configure a compressor and put some recordings through one to see what happens.
Discuss this tutorial here.
timestamp 0:19  Input and output meters are very important when using a compressor. Watching and adjusting the input signal will determine where the threshold and ratio should be configured i.e. when the compressor should kick in. The output meter will show what effect the compressor is having (although your ears should be the main guide).
timestamp 0:39  Configuring the threshold will determine when the compressor kicks in. As soon as the signal volume goes over it, the compressor will start to clamp down on it and reduce how much it goes up by.
The threshold and ratio are the most important controls for a compressor.
timestamp 1:04  We configure a ratio of 2:1 and see what happens to the test sound.

timestamp 2:18  Then we try again with a ratio of 4:1.

timestamp 2:28  And once more with a ratio of 50:1 ratio i.e. the compressor is working as a limiter.
timestamp 3:20  The attack controls how quickly the compressor reacts to the signal going over the threshold. A fast attack means that the compressor reacts very quickly and clamps down on any loudness as soon as it happens, but this can affect the quality of the sound. A slower attack will affect transients less but will allow some loudness to "leak" through.

timestamp 3:48  The release controls how quickly the compressor will turn off after it has started.

timestamp 3:55  Finally, we demonstrate a real example of using a compressor to control the dynamic range of a recording.