Expansion
From WikiRecording
There are two basic types of expansion: dynamic and downward.
Expansion increases the dynamic range or level of a signal after the signal crosses the expansion threshold. Dynamic expansion is basically the opposite of compression.
In fact, broadcasters use dynamic expansion to undue compression before transmitting the audio signal. This is commonly referred to as companding or COMPression followed by expANDING.
By far the most common use of expansion is downward expansion.
In contrast to compression, which decreases the level of a signal after rising above the compression threshold, expansion decreases the level of a signal after the signal goes below the expansion threshold. The amount of level reduction is determined by the expansion ratio.
For example, a 2:1 expansion ratio reduces the level of a signal by a factor of two. (e.g. if a level drops 5dB below the expansion threshold, the expander will reduce it to 10dB below the threshold.) Commonly used as noise reduction, expansion is very effective as a simple noise gate.
The major difference between expansion and noise gating is the fact that expansion is dependent on the signal level after crossing the threshold, whereas a noise gate works independent of a signals level after crossing the threshold.
Citation
This article is based on a PreSonus manual and are used with the kind permission from the people at PreSonus.
WikiRecording thanks PreSonus for their support of our community.
The original manuals can be found at PreSonus's Technical Support Website.
PreSonus Audio Electronics, Inc is not responsible for the content of this article.
