Facebook social media iconTwitter social media iconYouTube social media iconSubmit to Reddit

Equipping Your Home Recording Studio - A free download from Audio Masterclass

An Introduction to Equalization - A free download from Audio Masterclass

An Introduction to Compression: Basic Compression - A free download from Audio Masterclass

Do you need more plug-ins? Or more skills?

Can you hear the difference between a square wave and a sine wave?

Why choosing a key for your song is one of the most important aspects of preparation for production and recording

"There is background noise in my studio. Should I use a noise-reduction plug-in?"

Who should be responsible for the fade at the end of a song - the producer, mix engineer or mastering engineer?

Create an amazing trance riser in 7 steps

The new battlefield in the loudness war?

Exploring the MASSIVE headroom in your DAW

Do some microphones respond to EQ better than others?

The Making of a CD - FREE DOWNLOAD

The expander

The opposite of compression in sound engineering - expansion.


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.

Please click here if there are broken links or missing images in this article

By David Mellor Wednesday March 5, 2003
Online courses from Audio Masterclass