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the right output of the Vortex Device that will be connected to the right channel input of
the codec. Any microphones that are considered in the center should feed both left and
right outputs with a crosspoint attenuation of -3 dB.
•
Each microphone on the left side of the room should have its AEC set to R1. Each
microphone on the right side of the room should have its AEC set to R2.
•
In the VSX 8000 User Interface, go to S
P
S
OLYCOM
TEREO
•
Any stereo audio that is sent into the VSX 8000 will be reproduced on opposite channels at
the far end when sent to a Polycom stereo-compatible codec, i.e. left channel input will be
reproduced via the right loudspeaker and right channel input audio will be reproduced via
the left channel loudspeaker. This is done so that audio will track the video image on the
far side.
Here are some room design tips when using the Stereo AEC of the VSX 8000:
• We do not recommend using a channel separation any lower that -10 dB (e.g., -15 dB
would not be recommended).
• Most small to medium rooms with table microphones should work well with a channel
separation of 10 dB. These types of rooms would probably have a STI or RaSTI of .75 or
higher.
• For larger rooms or rooms with ceiling microphones, the channel separation may have to
be lowered (for instance to -5 dB) in order to prevent residual echo (echo that is never
fully removed by the AEC). If residual echo remains an issue, the VSX and Vortex may
have to be configured in mono mode (see the section entitled Standard AEC Operation)
• The use of front-of-room mounted stereo loudspeakers will enhance the stereo image.
• Distributed ceiling loudspeakers can also be used in addition to the front-of-room
loudspeakers to provide broader coverage. Note that the ceiling loudspeakers should be
assigned to a "left" or "right" zone and should be powered by a multi-channel amplifier.
The use of output delay with the ceiling loudspeakers can also enhance the stereo
realism. An approximation is 1 millisecond per foot delay to the signals that will be sent to
the distributed loudspeakers. The delay can be added from the Vortex outputs page
within Conference Composer.
An advantage to using the Vortex Device's internal AEC is that you can continue to use a Vortex
telephony interface, such as the Vortex EF2201, when operating in stereo with the VSX 8000
because a separate mono mix can be created in the Vortex matrix mixer to feed the telephony
interface separately.
S
.
URROUND
, A
S
YSTEM
DMIN
ETTINGS
, A
and select E
UDIO
NABLE
25
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