User Manual

THE MAIN MIXER
349
Gate/Expander
Gating or expansion will attenuate signals below a set threshold; the opposite of compression. It can be used to re-
duce or eliminate unwanted background noise that may be present when there is no signal to mask it. Gating is also
commonly used to reduce microphone “bleeding”, e.g. when recording a close-mic’ed drum kit you can use gating to
silence the tom microphones when the toms aren’t being played to tighten up the sound, and for special effects like
“keying” (see below).
Higher expansion ratios (10:1 and above) are referred to as noise gating, where the channel is completely silenced
if the level drops below the set threshold.
The Gate/expander has the following parameters:
About the Filters To Dynamics Sidechain button
When this button (found in both the Input and EQ sections) is activated, the Low Pass and High Pass filters can be
used to filter the channel sidechain signal before the dynamic processing.
The channel signal itself will not be directly affected by the filters, only the sidechain signal. The filtered sidechain sig-
nal is what triggers the dynamic processing, but the dynamic processing is applied to the channel signal. This allows
you to use frequency sensitive compression.
By trimming low and/or high frequencies you can specify which frequency range should trigger the compressor or
gate. A typical application of frequency sensitive compression is “de-essing” where harsh sibilants in vocal material is
reduced or eliminated. This is done by filtering the Sidechain signal so that only high frequencies (s noises) will trig-
ger the compressor.
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Parameter
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Description
Gate “ON” button Activates/deactivates the gate.
RANGE Sets the amount of gain reduction applied to signals below the set Threshold. The Range can be set from 0dB (no
reduction) to -40dB. If the EXP button is on (see below), the RANGE knob sets the expansion amount.
EXP button When activated this changes the operating mode from Gate to Expansion. The RANGE knob (see above) then
sets the expansion amount.
THRES (Threshold) This sets the level at which the gate opens or closes. Signals below the Threshold setting are gated, but when the
level exceeds the threshold, the gate opens.
Range: -52 dB to 0 dB
Note that the threshold for closing the gate is slightly lower than the threshold for opening the gate. This is to
avoid undesirable gate triggering with signal levels close to the set threshold.
REL (Release) Release determines the time it takes for the gate to go from open to fully closed. Fast release times will fade the
signal abruptly once the level falls below the threshold, and longer release times will slowly fade out the signal.
Range: 100ms to 1000ms.
FAST button Attack - the time it takes for the gate to open - is normally1.5ms per 40dB. If the FAST button is activated the at-
tack will be 100µs (microseconds) per 40 dB, which is useful for percussive material were the waveform rises
steeply in a very short time.
HOLD This determines the time the gate stays fully open after the signal falls below the threshold. Hold interacts with
the Release parameter such that Release only starts acting after the set Hold time.
Range: 0ms to 4000ms.
Meter The left LED meter shows the gain reduction applied by the gating/expansion.