User Guide

60 Chapter 4 Dynamics
Some compressors, called multiband compressors, can divide the incoming signal into
different frequency bands, and apply different compression settings to each band. This
helps achieve the maximum level without introducing compression artifacts, and is
typically used on an overall project mix.
Expanders
Expanders are similar to compressors, except that they raise, rather than lower, the
signal when it exceeds the threshold. Expanders are used to enliven the audio signal.
Limiters
Limiters (also called peak limiters) work in a similar way as compressors, in that they
reduce the audio signal when it exceeds a set threshold. The difference is that while a
compressor gradually lowers the signal level above the threshold, a limiter quickly
reduces any signal louder than the threshold to the threshold level. The main use of a
limiter is to prevent clipping while preserving the maximum overall signal level.
Noise Gates
Noise gates alter the signal in the opposite way that compressors or limiters do. While a
compressor lowers the level when the signal passes above the threshold, a noise gate
lowers the signal wherever it is below the threshold. Louder sounds pass through
unchanged, but softer sounds, such as ambient noise or the decay of a sustained
instrument, are cut off. Noise gates can be used mainly to eliminate low-level noise or
hum from an audio signal.
The following sections describe the effects included with Logic Studio.
 “Adaptive Limiter” on page 61
 “Compressor” on page 62
 “DeEsser” on page 65
 “Ducker” on page 67
 “Enveloper” on page 68
 “Expander” on page 70
 “Limiter” on page 71
 “Multipressor” on page 72
 “Noise Gate” on page 76
 “Silver Compressor” on page 78
 “Silver Gate” on page 79
 “Surround Compressor” on page 79