Manual-6
Duck Mode
Ducking reduces the level of a signal by a certain amount (the
depth) when the side-chain key signal exceeds a set threshold.
Ducking is useful for voiceover and instrument solo applications.
Example uses
• Automatically duck music when an announcement is made.
Connect the music signal to the main input, connect a signal
from the announcement microphone to the side-chain key
input. When the announcer speaks, the key input exceeds the
set threshold, and music is automatically turned down.
• Automatically duck the bass by a few dB every time the kick
drum is hit. Connect the bass to the main input, connect a
signal from the kick drum to the side-chain key input. Use a
relatively shallow depth.
Figure 5: Ducker
Kick Drum Attack Example
The pictures below show the affect of attack time on the leading
edge of a kick drum. The blue trace shows the Gate input signal.
The yellow trace shows the Gate output signal. The time differ-
ence between the two signals represents the total propagation
delay through the Gate. The Gate Threshold is set to about 80%
of the peak value. The Gate Depth is 20 dB.
The first complete cycle of the kick drum defines its sound, as
subsequent cycles are considerably lower in amplitude. The kick
drum’s sound is significantly changed if the gate can not accu-
rately capture the first cycle. Look ahead without ramping often
causes an audible click at fast attack and moderate to extreme
depth settings. Only look ahead pre-ramping – as done in the
G4 – accurately reproduces the 1
st
cycle of a kick drum without
adding excessive delay or significantly altering the leading edge.
107405
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The above graph shows the operation of the Ducker. A
Ducker works the opposite of a Gate. The signal is attenuated
when the side-chain key input goes
above
threshold. In the above
example, the dashed-line green trace shows the signal being
ducked. The solid-line red trace shows the external key input.
The threshold is set at –20 dBu. When the key input goes above
-20 dBu, the main signal is ducked by an amount set by the
depth control, in this case around 45 dB.
Note: All applications of ducking use the external side-chain key
input.
1m
20
10m
100m
1
5
V
-80
+20
-70
-60
-50
-40
-30
-20
-10
0
+10
-60
+20
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
+5
+10 +15
SIDE-
CHAIN INPUT
DUCKED SIGNAL
INPUT dBu
O
U
T
P
U
T
d
B
u
The first figure shows the response with a 0 ms attack time. The lead-
ing edge is defined by the look-ahead ramping. Note the leading edge
of the output is almost identical to the input signal.
The second figure shows the response with a 1 ms attack.
The slower rise time softens the sound of the leading edge.
