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Appendix
176
■ Gate and Ducking
A gate, or noise gate is an audio switch used to mute sig-
nals below a set threshold level. It can be used to sup-
press background noise and hiss from valve (tube) amps,
effects pedals, and microphones.
Ducking is used to automatically reduce the levels of one
signal when the level of a source signal exceeds a speci-
fied threshold. It is used for voice-over applications
where, for example, level of background music is auto-
matically reduced, allowing an announcer to be heard
clearly.
Gate (GAT) and Ducking (DUK) parameters:
Threshold sets the level at which the gate closes, cutting
off the signal. Signals above the threshold level pass
through unaffected. Signals at or below the threshold
cause the gate to close.
For ducking, trigger signal levels at and above the thresh-
old level activate ducking, and the signal level is reduced
to a level set by the Range parameter.
The trigger signal is determined using the KEY IN param-
eter.
Range controls the level to which the gate closes. It can
be used to reduce the signal level rather than cut it com-
pletely. At a setting of –70 dB, the gate closes completely
when the input signal falls below the threshold. At a set-
ting of –30 dB, the gate only closes so far allowing an
attenuated signal through. At a setting of 0 dB, the gate
has no effect. When signals are gated abruptly, the sud-
den cutoff can sound odd.
For ducking, a setting of –70 dB causes the signal to be
virtually cutoff. At a setting of –30 dB the signal is
ducked by 30 dB. At a setting of 0 dB, the duck has no
effect.
Attack determines how fast the gate opens when the sig-
nal exceeds the threshold level. Slow attack times can be
used to remove the initial transient edge of percussive
sounds. Too slow an attack time makes some signals
sound backwards.
For ducking, this controls how soon the signal is ducked
once the duck has been triggered. With a fast attack time,
the signal is ducked almost immediately. With a slow
attack time, ducking fades the signal. Too fast an attack
time may sound abrupt.
Hold sets how long the gate stays open or the ducking
remains active once the trigger signal has fallen below
the threshold level.
Decay controls how fast the gate closes once the hold
time has expired. A longer decay time produces a more
natural gating effect, allowing the natural decay of an
instrument to pass through.
For ducking, this determines how soon the ducker
returns to its normal gain after the hold time has expired.
Threshold = –10dB
Range = –30dB
Range = –70dB
–70
–60
–50
–40
–30
–20
–10
0
+10
+20
–70 –60 –50 –40 –30 –20 –10 0 +10 +20
dB
dB
Range = –30dB
Threshold = –20dB
–70
–60
–50
–40
–30
–20
–10
0
+10
+20
–70 –60 –50 –40 –30 –20 –10 0 +10 +20
dB
dB
Output Level
Input Level
Output Level
Input Level
Parameter Value
Threshold (dB)
–54 to 0 (55 points)
Range (dB) –70 to 0 (71 points)
Attack (ms) 0 to 120 (121 points)
Hold (ms) 0.02 ms to 2.14 sec (216 points)
Decay (ms) 6 ms to 46.1 sec (160 points)