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
What They Do And Why We Use Them
In this video, we look at what a compressor does and why they are used.
Discuss this tutorial here.
timestamp 0:20  If some parts of a recording are too quiet, we can't just increase the volume because
  • there may not be enough headroom
  • the loud parts will become too loud
timestamp 0:45  
  • Dynamic range
    The difference in volume between the loudest and quietest parts of a recording.
  • Headroom
    How much we can increase a signal's volume before it reaches the maximum.
  • Threshold
    Everything quieter than the threshold will remain unchanged, everything over it will have its volume reduced.
  • Ratio
    Controls how much the volume gets reduced once it goes over the threshold.
timestamp 1:29   A compressor can be configured to work as a limiter by setting a really high ratio, which stops the volume from ever going over the threshold.
timestamp 1:40   By using a compressor to squash down the loud parts of a recording, we get more headroom and can then increase the recording's volume by more.
timestamp 1:56   In summary, we use a compressor
  • to reduce the dynamic range of a recording,
  • which evens out changes in volume,
  • and allows us to increase the overall volume.