MOTU 1248 User Manual page 84

the signal to 2 dB above the Threshold. When the
input level goes above the threshold, the
attenuation is added gradually to reduce distortion.
The rate at which the attenuation is added is
determined by the Attack parameter. Likewise,
when the input level falls below the Threshold, the
attenuation is removed gradually. The rate at which
the attenuation is removed is determined by the
Release parameter. Long Release times may cause
the audio to drop out briefly when a soft passage
follows a loud passage. Short Release times may
cause the attenuation to "pump", a term used to
describe the sound of the compressor when the
average input level quickly fluctuates above and
below the Threshold. These types of issues can be
addressed by adjusting the compressor's
parameters, or applying the Leveler instead. Gain
adjusts the overall output level of the compressor,
post processing. The Level meter (Figure 8-4)
shows the level of the input signal entering the
compressor. It shows either the Peak envelope or
the RMS level, if enabled.
Ratio handle
Threshold
handle
84
Figure 8-5: The full-size Compressor graph.
Gain reduction meter
The Gain reduction meter (Figure 8-4) displays the
current amount of attenuation applied by the
compressor, before the makeup gain stage.
RMS mode
By default, the compressor operates in Peak mode,
which uses signal peaks to determine the input
level. In RMS mode, the compressor measures the
input signal's loudness, using the root-mean-
square computational method. When RMS is
disabled, RMS mode will let brief peaks through
because the detector sidechain is only looking at
the average signal level. By contrast, peak mode
will catch those brief peaks. Peak mode is generally
used for drums, percussion and other source
material with strong transients, while RMS mode is
mostly used for everything else.
The level meter shows either the peak level or the
RMS level, depending on the mode.
Auto Makeup
When Auto Makeup Gain is engaged (Figure 8-4
and Figure 8-5), the compressor dynamically
compensates for any gain reduction, to preserve
the original loudness of the signal.
M I X E R E F F E C T S