Vortex Media VTX 1000 - Manual (Page 69)

In order to satisfy the sound reinforcement requirements, Mic 9 in Vortex EF2280 ID 01 has been placed on
the W Bus, Mics 10 and 11 have been placed on the X Bus, Mics 12-14 have been placed on the Y Bus, and
Mics 15-16 have been placed on the Z Bus. In order to remove those signals from the EFBus so that we can
send them to the outputs of Vortex EF2280 ID 00, we need to assign the WB1, XB1, YB1, and ZB1 signals to
one of the three mix signals that are available per each W, X, Y, or Z bus channel (Before we go further,
remember that the "1" after each EFBus Input (WB1, XB1, YB1, and ZB1) refers to the device ID of the unit
that placed that signal onto the bus). In this case, WB1 is assigned to WM0, XB1 is assigned to XM0, YB1
is assigned to YM0, and ZB1 is assigned to ZM0. Once a signal has been assigned to one of the mixes
(WM0 for example), then it is now a valid input to the Matrix Mixer of Vortex EF2280 ID 00.
Also, note that the Vortex EF2280 ID 00 is exporting its reference signal to the EFBus. This is to allow the
same audio signal to be removed from the local microphones in the other Vortex EF2280 in the system.
Only one signal can be exported as a AEC Reference Signal over the entire EFBus. As a result, the other
Vortex EF2280 in the system cannot export a signal (and should not need to).
Matrix Mixer
The matrix mixer will need to be changed from the default settings in order to use Outputs 1 and 2 for the
Amplifier, Output A for the video codec, Output B for the Interface Module, and Output D for the Subwoofer.
Inputs 1-8 need to be assigned to Outputs A and B so that the people on the far end of a SoundStation VTX
1000 or video codec call can hear the local microphones. The cross-points are colored blue to indicate that
they are gated to Outputs A and B.
Inputs C and D are attenuated by 3 dB to Outputs D, Y, and R1 because if the left and right channels are
mono, both channels will increase 6 dB in gain
3 Inputs C and D are reduced by 10 dB to Output A and B
because if a program source is mixed at 0 dB with local speech, it may be difficult for the remote person on
the telephone to distinguish between the program audio and the local speech because of the frequency
limitations of the telephone network. By attenuating the program audio, you "bias" the audio sent to the
telephone in favor of the local speech.
The Interface Module (Input B) needs to be assigned to all outputs except Output B. If Input B is assigned
to Output B, then you will create a loopback inside the Vortex EF2280. This will cause the far end of the
SoundStation VTX 1000 to hear an "echo" of themselves although it is an electronically created echo and
not an acoustic echo. The same logic applies to the video codec (Input A / Output A).
Inputs A, B, C, and D and Outputs A and B are set to +10 dB and -10 dB respectively. Please refer to the
section entitled “Gain Structure” under the W
IRING THE S OUND S TATION VTX 1000 TO A V ORTEX D EVICE heading
for more information as to the reasoning behind the gain levels.
3 If two signals with an amplitude of 1V peak-to-peak each are added together, the summed signal’s amplitude will be 2V peak-
to-peak. In terms of decibels, that can be expressed as 20*log (2V / 1V) which equals 6 dB).
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