Reference Manual

302 Live Audio Effect Reference
the signal, and may lead to a slight “buzziness” caused by distortion. Short release times can
cause ”pumping” as the compressor tries to figure out whether to compress or not; while gener-
ally considered an undesirable effect, some engineers use it on full drum kits to give unusual
”sucking” effects. Careful adjustment of attack and release times is essential when it comes to
compression of rhythmical sources. If you are not used to working with compressors, play a
drum loop and spend some time adjusting Attack, Release, Threshold and Gain. It can be very
exciting!
A compressor can only react to an input signal once it occurs. Since it also needs to apply an at-
tack/release envelope, the compression is always a bit too late. A digital compressor can solve
this problem by simply delaying the input signal a little bit. Compressor offers three different
Lookahead times: zero ms, one ms and ten ms. The results may sound pretty different depending
on this setting.
Compressor can be switched between three basic modes of operation. With Peak selected,
Compressor reacts to short peaks within a signal. This mode is more aggressive and precise,
and so works well for limiting tasks where you need to ensure that there are absolutely no signals
over the set threshold. RMS mode causes Compressor to be less sensitive to very short peaks
and compress only when the incoming level has exceeded the threshold for a slightly longer
time. RMS is closer to how people actually perceive loudness and is usually considered more
”musical.”
In Expand mode, the Ratio can also be set to values below 1. In this state, Compressor acts as
an upward expander, and will increase the gain when signals exceed the threshold. (For more
information about the various types of dynamics processing, see the Multiband Dynamics chap-
ter (page 336).)
In addition to these modes, Compressor can be switched between two envelope follower
shapes that offer further options for how the device measures and responds to signal levels. In
linear (Lin) mode, the speed of the compression response is determined entirely by the Attack
and Release values. In logarithmic (Log) mode, sharply compressed peaks will have a faster
release time than less compressed material. This can result in smoother and less noticeable com-
pression than Lin mode. Note that the Lin/Log switch is not visible in Compressor’s collapsed
view.