Basics Of Compression; What Is Compression - Alesis CLX440 Reference Manual

This section will explain how compression works, and explain
the functions of the CLX-440's controls.

What is compression?

A compressor essentially turns down the volume of any audio
which is louder that a set level. This level is called the
compressor threshold level. If the input signal stays below the
setting of the threshold level, nothing will happen. When the
input signal is louder than the compressor threshold, this signal
is reduced in volume.
The amount of reduction is determined by the compression
ratio. A ratio of 2:1 means that for every 2 dB above the
threshold level, the output will only get 1 dB louder. If the ratio
is 8:1, the input signal will have to be 8 dB louder than the
threshold to get 1 dB louder after compression. If the ratio is
infinity to one (∞:1), this is referred to as limiting. Limiting
means that the output will never get any higher than the
threshold setting.
Compression is used for:
• Keeping recording levels under control so that the recorder
doesn't distort
• Keeping vocal or instrument performances in the same
general level range so that they're easier to mix with other
instruments
• Compressing the mix output so that it doesn't exceed a
certain technical maximum in broadcast or post production
• In live sound reinforcement, keeping the volumes under
control so that they don't distort
• Making tracks sound "punchy"
Compressors can make your recorded tracks sound polished and
professional.
various instruments.
CLX-440 Reference Manual

Basics of Compression

Chapter 5
will give specific example settings for
Chapter 3
27