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AM-10HD / Aug 2008
A M - 1 0 H D G U I
AM Limiter Controls
The graphic below shows the controls available for the lookahead limiter and the text
below it describes each Limiter control according to its function.
Limiter Enable
When this checkbox is checked the lookahead limiter is enabled.
L/R Linked
When this box is checked the left and right channel control signals are common. This
prevents unnatural stereo image shifts when one channel needs to reduce the signal to con‑
trol peak excursions.
Limiter Thresh
Adjusts the relative threshold of the lookahead limiter compared to the setting of the
Lim/Clip Drive control, and is adjusted until the onset of limiting is reached with normal
program material as indicated by the AM limiter gain reduction bargraph. The range of this
control is +/‑6dB.
Attack
Adjusts the attack time of the lookahead limiter. Note that attack time settings from 0.2
milliseconds through 0.5 milliseconds allow the limiter to “lookahead” in time and react to
signal peaks
before
they arrive at the limiter’s gain control algorithm.
Attack time settings greater than 0.5 milliseconds, and up to the limit of
100 milliseconds, cause the limiter to operate conventionally. For example, if the attack
time control is set to 1.0 milliseconds, the actual attack time is 0.5 milliseconds because the
0.5 millisecond lookahead is
always
in circuit, and its value must be subtracted from any
adjustment of 0.5 milliseconds or greater in order to know the actual attack time.
Release
Controls the primary (fast) release time of the lookahead limiter.
Slower settings (longer release times) cause the peak limiter to recover more slowly
from limiting; release times set too slow may allow undesirable signal ducking to occur.
Conversely, fast release times increase signal density, and release times that are too fast
result in increased intermodulation distortion which can “muddy” the sound.
The overall range of the control is from 33 milliseconds to 330 milliseconds.
AM Lookahead Limiter
