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Dugan Model E-2A User Guide
Gain Limiting
Gain Limiting is used along with the Music System—the Speech System doesn't need
it. It reduces master gain as new mics become active, thus avoiding feedback and
noise. This is commonly called NOM (number of open mics) gain adjustment. Unlike
NOM functions on other systems, Dugan Gain Limiting does not base its gain limiting
calculation on the number of open mics. Instead it sums the gains of all active
channels (including partially attenuated channels), compares them to a gain
threshold, and reduces the gain appropriately.
10
8
6
Gain
Reduction
(dB)
4
2
0
0
Number of Open Mikes
Figure 2-5 NOM and gain reduction: NOM =1 (left); NOM = 4 (right)
Conventional automatic mixing implementations always assume an NOM of 1. The
Dugan's unique implementation allows you to set the number of mics that will
operate at full gain before gain limiting occurs. For example, if there is enough gain
before feedback to tolerate four open mics, the gain limit can be set to 4. Gain reduction
begins when the fifth mic turns on.
NOTE:
Since the Model E-2A has no master audio channel, Gain Limiting reduces the gain on all
channels in the group for which NOM is active.
2
4
6
8
(NOM)
Theory of the Speech and Music Systems
4
Gain
Reduction
(dB)
2
0
15
0
2
4
6
Number of Open Mikes
(NOM)
8
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