Specifications

DigiRack Plug-Ins Guide66
Limiting is used to prevent short-term peaks
from reaching their full amplitude. Used judi-
ciously, limiting produces higher average levels,
while avoiding overload (clipping or distortion),
by limiting only some short-term transients in
the source audio. To prevent the ear from hear-
ing the gain changes, extremely short attack and
release times are used.
Limiting is used to remove only occasional
peaks because gain reduction on successive
peaks would be noticeable. If audio material
contains many peaks, the threshold should be
raised and the gain manually reduced so that
only occasional, extreme peaks are limited.
Limiter Controls
Phase Invert Inverts the phase (polarity) of the
input signal to change frequency response char-
acteristics between multi-miked sources or to
correct for miswired microphone cables.
Gain Provides overall output gain adjustment.
Input Meter Indicates the level of the unproc-
essed input signal to the Limiter.
Output Meter Indicates the output level of the
Limiter, including any gain compensation
added with the Gain control.
Reduction Indicates the amount by which the
signal is being attenuated.
Threshold Sets the threshold level. Signals that
exceed this level will be limited. Signals that are
below it will be unaffected.
Attack Sets the Limiter’s attack time. The
smaller the value, the faster the attack. The
faster the attack, the more rapidly the Limiter
applies attenuation to the signal. If you use fast
attack times and heavy limiting, you should
generally use a proportionally longer release
time, particularly with material that contains
many peaks in close proximity.
Release Controls how long it takes for the Lim-
iter to be fully deactivated after the input signal
drops below the threshold level. In general, if
you use heavy limiting, you should use propor-
tionally longer release times in order to avoid
pumping that may occur when the Limiter is
forced to jump back and forth between limited
and unlimited signal levels. Lengthening the re-
lease time will help smooth these changes in
level by introducing a lag in the ramp-up/down
time of attenuation. Use shorter release times on
material with fewer peaks that do not occur in
close proximity to each other.
Graph Displays the response curve set by the
Limiter’s Threshold setting. As you adjust these
controls, refer to the graph to see how the shape
of this curve changes.
LFE Enable Enables plug-in processing of the
LFE (low frequency effects) channel on a multi-
channel track formatted for 5.1, 6.1, or 7.1 sur-
round formats on some plug-ins. To disable LFE
processing, deselect this button. For more infor-
mation on the LFE channel, refer to the Pro Tools
Reference Guide.
External Key Enables and disables side-chain
processing. Side-chain processing uses the vary-
ing amplitude of a separate reference track to
trigger limiting. See “Side-Chain Processing” on
page 22.