5.1 DigiRack Plug-Ins Guide - Digidesign Support Archives

Limiter II
Limiter II plug-in
The Limiter is used to prevent signal peaks from
ever exceeding a chosen level so that they don’t
overload amplifiers or recording devices. Most
limiters have ratios of 10:1 or 20:1, although
some provide ratios of up to 100:1. Large ratios
effectively limit the dynamic range of the signal
to a specific value by setting an absolute ceiling
for the dynamic range.
Limiting is used to prevent short-term peaks
from reaching their full amplitude. Used judiciously,
limiting allows you to achieve higher
average levels, while avoiding overload (clipping
or distortion), by limiting only some shortterm
transients in the source audio. To prevent
the ear from hearing 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 wouldn’t 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.
The Limiter’s ratio is internally set to 100:1, and
the Attack time is automatically set to 0 milliseconds.
The Limiter is similar to heavy compression.
It can be useful for reducing pops and
clicks, or for hard-limiting dynamic range for
broadcast or band-limited mediums such as cassette.
Limiter Parameters
Phase Invert Inverts the phase (polarity) of the
input signal, allowing you to change frequency
response characteristics between multi-miked
sources or to correct for miswired microphone
cables.
Gain Provides overall output gain adjustment.
Input Meter Indicates the level of the unprocessed
input signal to the Limiter.
Output Meter Indicates the output level of the
Limiter, including any gain compensation
added via the Gain parameter.
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.
Chapter 4: DigiRack Real-Time TDM and RTAS Plug-Ins 29