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AUDIO ROUTING •
EXPANSION BUS
27
Outputs 9-12 - These are line-level outputs on the rear panel terminal blocks. This is typically audio
that goes to an APV200-IP video codec, XAP TH1 telephone interface, tape recorder, power amp,
and other audio devices. Normally, this audio contains auxiliary audio and audio from other
networked XAP 800 units. In the default routing, inputs 9-12 (minus your channel input) and
master auxiliary mix (all auxiliary audio from other XAP 800 units) are contained in this audio.
Expansion Bus
Expansion Bus This is a digital bus that appears at every XAP 800 networked on the system. This
is a mix-minus bus. Any audio placed on the bus for a particular unit is not fed back to that unit
when audio is taken off that bus. Audio on any networked XAP 800 can be placed on a bus or
audio can be taken off a bus and routed to any destination within the unit. The XAP 800 system
has 12 digital mix-minus buses with the following default programming:
O-R Buses These four audio buses are defaulted as the mic mix buses; they can communicate the
NOM count (see page 25) across the network to other XAP 800s. Otherwise, these buses are
identical to buses S-Z.
S-Z Buses These eight buses are defaulted as auxiliary mix buses. They are used to route auxiliary
audio, such as from an APV200-IP video codec, XAP TH1 telephone interface, between units on
the network. These buses are used as mic mix buses when NOM count is not required.
PA Adapt Expansion Bus Reference Buses The Expansion Bus reference buses provide a system-
wide bus for mic channels to receive a reference input for PA Adaptive Mode and acoustic echo
cancellation. For example, say you have four XAP 800 units Expansion Bused together. Audio on
output 12 of unit 1 is audio routed to the PA system in the room. This audio is needed as a
reference for mics on units 2, 3 and 4 so that speaker audio does not gate on the mics and the
echo canceller cancels the appropriate audio. This is accomplished by selecting output 12 on unit
1 as Expansion Bus reference and then selecting microphones of units 2, 3, and 4 to use
Expansion Bus reference.
See Chapter 4, for more information about the XAP 800’s filters.
Assignable Processing
There are eight assignable processing buses in the XAP 800. Unlike with other matrix mixers,
these buses can route any input or group of inputs to any output or group of outputs. Also, these
combined sources can be filtered, delayed, compressed, and attenuated to provide specific
enhancements to the audio (see Figure 15). These buses would typically be used to reduce
feedback in the venue and provide crossovers for different speaker systems.
500mS
Compressor
Notch
Figure 15. Assignable Processing
Summary of Contents for XAP 800
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