Crown Audio IQ-MSD Turbo Software - Manual (Page 160)

IQ–MSD Turbo 1.4 Advanced IQ System Software
Page 160
Several of the AMB function controls interact with each other. For this reason we recommend that they be
configured in the order shown below:
1. Double-check the Gate function Max Gain settings of each input to be sure they are set properly to limit all
input gains to safe levels.
2. Set the Ambient Offset Control to a desired level below the Max Gain settings.
3. Set the Threshold of the ambient sense input to an appropriate level so that the AMB function begins to
operate at an appropriate time. This may require some experimentation.
4. Set the Expansion Ratio so that the dynamic range of the ambience level does not exceed the available
headroom of the system.
5. Set the Attack and Decay Time controls to appropriate speeds.
6. Set the Guard Band to the desired offset below the Threshold (if desired). Normally, this can be turned off
by setting it to 0 (zero).
7. Turn on the AMB function with the Ambience control.
Next, the controls are described in the order in which they are listed on the Sub-block screen.
Ambience: The AMB function is turned on and off with the Ambience control.
Attack Time: The Attack Time control determines how rapidly the AMB function will begin to increase the
output level of Channel 1 above the Ambient Offset level. Slower Attack Times cause the AMB function to respond
slower to increases in ambient level and prevent it from responding to sudden increases in level.
Decay Time: The Decay Time control determines how rapidly the AMB function will begin to reduce the output
level of Channel 1 while the ambient sense input level is dropping. Slower Decay Times cause the AMB function
to respond slower to decreases in ambient level.
Expansion Ratio: The Expansion Ratio control determines how much the gain of output Channel 1 will
increase for every increase in the ambient signal level above the Threshold setting. A 4:1 Expansion Ratio setting
will raise the output gain 1 dB for every 4 dB that the ambient signal increases.
Most of the time the Expansion Ratio can be set to 1:1 so that the output level increases 1 dB for every increase
in the ambient sense level. However, if the ambient noise level has an extremely wide dynamic range it is possible
to exceed the headroom of the system. This is when you will want to use the Expansion Ratio control to reduce
the dynamic range of the AMB function.
Guard Band: The Guard Band control is an offset to the Threshold control. For example, if the Guard Band
is set to 3 dB, the threshold will be 3 dB below the Threshold control setting. It is provided as a tool for making
temporary adjustments to the Threshold level during setup. Normally, it should be set to 0 (zero) so that the
Threshold control setting accurately represents the actual threshold.