Polycom EF2201 Application Note page 16

– holding the mouse over the zone name on the top will show which amplifier is in
that zone.
By default each zone of microphones is mapped to the remaining loudspeaker
zones with a gain of -30dB. In this zone matrix view, the columns are summed to
create the outputs to the loudspeaker amplifier zones. For example, in Figure 13,
the reinforcement for Zone 1 is the sum of the microphones in Zone 2 (attenuated
by 30dB) the microphones from Zone 3 (attenuated by 30dB), and the presenter
microphones (also attenuated by 30dB). Please note that the microphones from
Zone 1 are NOT included in the output for Zone 1 and consequently the crosspoint
is grayed out to minimize the occurrence of acoustic feedback from a microphone
in a zone being reinforced into the same zone.
Figure 13. Default Zone gain matrix for this example.
The reinforcement levels from microphones to loudspeaker zones can be adjusted
by left clicking on the appropriate crosspoint and adjusting the slider that appears
on the left. Figure 14 shows setting the Zone 2 to Zone 1 reinforcement level to -
18dB.
The amount of reinforcement required will depend on the room design, the
physical separation between zones, and the style and placement of microphones
and loudspeakers. A conservative reinforcement level is recommended as a
starting point to minimize the incidence of acoustic feedback within the room.
After configuring the devices with the specified room reinforcement level, it is
possible to change the reinforcement levels either in the Vortex devices by
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