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Ultimate Mixing Console Processing

All about compression
The word “compression” is commonly used to describe two very different processes:

  • Digital Audio Data Compression (e.g. MP3, AAC, etc.)
  • Audio Level Compression (Dynamics Control)

In this context we are talking about the second process — dynamics control. Dynamics control is the process of automatically adjusting the volume control on an audio channel. The gain level of the channel is automatically adjusted by the process based upon the level of the audio signal passing through the processes detector. A compressor is a dynamics control processor that lowers the volume of the signal when the overall level of the signal increases. As a result, it tends to moderate or compress the dynamic range of the signal.

Compressors have a huge number of applications. They can be used as so-called “leveling-amplifiers” or automatic gain controls, which tend to keep the overall volume of the material constant. They can be used as limiters, which ensure that no matter what the level of the input signal is, the output level will never go above a specified level. They can be used to simply limit the overall dynamics of the signal, or they can be used to creatively change the timbre of the signal.

Most of the various applications can be accomplished by adjusting the parameters of the compressor; some applications depend on how the compressor is implemented. Depending on the compressor’s implementation, it may not be possible to actually achieve all modes of operation by adjusting the parameters. For example, many compressors (including the one in ChannelStrip) are not terribly effective as limiters; the limiting process may require a different approach to computing and applying the gain than a specific compressor provides.

Compressor parameters
Compressors have a wide variety of control parameters, but the most common ones are: