User Manual

Processing
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faded between the uninverted and inverted states so the signal level will drop briefly when you flip the state
of the phase invert switch, but it will not introduce a glitch or click into your audio.
After the the phase invert block the audio is routed through an input gain block that provides input gain of up
to +24 dB. You can use this gain to condition signals that are low in level.
This input gain may also be used to pad out signals by up to –24 dB. While you may find this attenuation useful
to just bring down the level through the strip simply and quickly, you must realize that this gain is applied
after the signal reaches ChannelStrip and will not pad out any clipping that occurs in the A/D converters or
in a plug-in that is inserted before ChannelStrip.
The input gain is controlled by the “In Gain” knob.
Gate/Expander
The next processing block is the Gate. The gate is used to adjust the low level dynamics of the signal being
processed. Through the use of the external side-chain the gate can be used to do acoustic triggers. In addition,
the side chain filter may be used to make the control of the dynamics frequency sensitive. This can be useful
when you are trying to gate out a noisy signal that has a specific, very strong signal in a limited frequency
range when you want the gate to open.
Figure 5.3: Gate/Expander
Theory Of Operation
Based upon your setting for the sidechain routing switch, either the Pro Tools sidechain input signal or the
channel signal is fed to the sidechain filter. The sidechain filter provides one band of equalization that may
be used to accentuate or cut certain frequencies (parametric or shelf filters) or limit the key to a certain range
of frequencies (cut or bandpass filters). You control the filter type and the filter parameters with the filter type
button and the “dB”, “Hz” and “BW” knobs.
You can enable the side chain filter with the green “SC Ena” button.
After the sidechain signal has been processed by the sidechain filter it is measured by a level detector that
determines the instantaneous level of the signal (in the case that ChannelStrip is running in stereo mode the
detector is linked with the other channel in the stereo pair and the higher level of the two channels is used).
When the gate is enabled the signal will be attenuated based on how much the detected level is below the
threshold you set with the “Thresh” knob.
The dynamic behavior of the opening and closing of the gate is controlled with the “Attack” and “Release”
knobs.