DigiDesign DigiRack, Manual

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Chapter 6: DigiRack Real-Time TDM and RTAS Plug-ins 73
Threshold
The Threshold control sets the level below
which an input signal must fall to trigger expan-
sion or gating. Signals that fall below the thresh-
old will be reduced in gain. Signals that are
above it will be unaffected.
An orange arrow on the Input meter indicates
the current threshold, and can also be dragged
up or down to adjust the threshold setting.
The Dynamics Graph display also shows the
threshold as an orange vertical line.
This control has an approximate range of
–60 dB to 0 dB, with a setting of 0 dB equivalent
to no compression or limiting. The default value
for the Threshold control is –24 dB.
Ratio
The Ratio control sets the amount of expansion.
For example, if this is set to 2:1, it will lower sig-
nals below the threshold by one half. At higher
ratio levels (such as 30:1 or 40:1) the Ex-
pander/Gate functions like a gate by cutting off
signals that fall below the threshold. As you ad-
just the ratio control, refer to the built-in graph
to see how the shape of the expansion curve
changes.
This control ranges from 1:1 (no expansion) to
100:1 (gating).
Attack
The Attack control sets the attack time, or the
rate at which gain is reduced after the input sig-
nal crosses the threshold. Use this along with
the Ratio setting to control how soft the Ex-
pander’s gain reduction curve is.
This control ranges from 10
μ
s (fastest attack
time) to 300 ms (slowest attack time).
Hold
The Hold control specifies the duration (in sec-
onds or milliseconds) during which the Ex-
pander/Gate will stay in effect after the initial
attack occurs. This can be used as a function to
keep the Expander/Gate in effect for longer pe-
riods of time with a single crossing of the
threshold. It can also be used to prevent gate
chatter that may occur if varying input levels
near the threshold cause the gate to close and
open very rapidly.
This control ranges from 5 ms (shortest hold) to
4 seconds (longest hold).
Threshold arrow on Input meter
Threshold indicator on Dynamics Graph display
Threshold
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Threshold