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The expander

A post by David Mellor
Wednesday March 05, 2003
The opposite of compression in sound engineering - expansion.
The expander

An expander is a more sophisticated form of gate. Whereas a gate is either on or off, an expander increases the dynamic range when the signal is below the threshold.

  • When the signal is above the threshold level, there is no change.
  • When the signal is below the threshold, the quieter the signal gets, the expander will make it even more so.

The expander has a ratio control like a compressor. 1:1 means no expansion; 20:1 means that the expander is working almost like a gate.

The expander isn't as useful a device as one might think. The problem is noise modulation - as the signal level goes up and down, below the threshold, the noise level will also go up and down.

This is an unpleasant effect known as 'breathing' or 'pumping'. Breathing and pumping can be evident in the compressor, but since it is high level signals that are being processed, they are better able to mask the noise.

A post by David Mellor
Wednesday March 05, 2003 ARCHIVE
David Mellor has been creating music and recording in professional and home studios for more than 30 years. This website is all about learning how to improve and have more fun with music and recording. If you enjoy creating music and recording it, then you're definitely in the right place :-)
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