Stereo Detection; Look Ahead Compression - Alesis CLX440 Reference Manual

Stereo Detection

The CLX-440 takes the greater of both left and right sides of each
channel before they are detected for compression or expansion.
The reason for this is so the two sides of a stereo signal are not
gain reduced differently.
For example, if a guitar was panned to the right and went above
the threshold level, and the left and right sides were not linked,
only the right side would be gain reduced. In this case, the stereo
image of anything panned center would shift to the left.
To keep this from happening, the left and right detectors of a
channel are always simultaneously checked. This is why you
should use the left and right sides of a channel - rather that
sending the left side of a signal to compressor channel A and the
right side to channel B. In addition to wasting a compressor
channel, you may cause the center imaging of your signal to
wander.

Look Ahead Compression

The CLX-440 has a feature called
an audio delay to provide immediate compression.
When a signal is input, the detector takes 0.02ms to determine its
level and apply gain reduction at it's fastest attack setting. In
some applications, this allows a quick transient to be passed
through the compressor before gain reduction is applied. Look
Ahead Compression delays the signal by 2ms to give the
detector time to apply compression. In most applications, this
delay is not noticeable and the gain reduction will appear to be
instantaneous.
This feature is especially useful as a mix compressor, making
sure that the stereo mix does not overload the mixdown
recorder.
CLX-440 Reference Manual
chapter 3 • basics of compression
LOOK AHEAD
. This feature uses
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