Chapter 5: Installation
120 EST3X Technical Reference Manual
Digital audio wiring
A digital audio riser consists of a single pair (Class B) or two pairs (Class A) of
wires that connect all amplifiers together. Since the digital signals are
multiplexed, any of eight independent audio sources can be directed to any
amplifier connected to the network. All command and control signals for the
audio system are distributed over the network data riser. Refer to the SFS1-CPU
Main Board Installation Sheet (P/N 3101773) for connecting digital audio riser
field wiring.
Audio amplifiers
The audio amplifier’s output is a dedicated and supervised speaker circuit that
covers one audio zone in the protected facility. An independent supervised
Class B or Class A, 24 VDC, 3.5 A, notification appliance circuit is provided on
the 20 and 40 watt amplifiers.
Figure 14 on page 83 is an example of an enclosure with two zone amplifiers and
a backup amplifier. In response to an alarm, selected audio amplifiers have been
connected to the required audio channels.
Backup amplifiers
Each cabinet can contain one zoned amplifier module that automatically backs
up the primary zoned amplifier module in the event of failure (not a field wiring
problem) installed in the same cabinet. All the amplifiers must have the same
output voltage rating.
Note: A backup amplifier will back up a failed amplifier if it was being used for
Page, EVAC, or Alert. It will not back up an amplifier being used on an Auxiliary
or General channel.
Refer to Figure 15 on page 84 for an example of a primary amplifier failure
causing the backup amplifier to automatically connect to the same audio source
as the failed amplifier to replace its output.
Preamp supervision module
The MN-PASM2 Preamp Supervision Module supervises preamp (line level)
audio signals.
The MN-PASM2 trouble relay contacts transfer 10 to 60 seconds after losing the
audio signal and immediately after losing power. The contacts restore
automatically after the audio signal or power returns.
The module installs in a single-gang electrical box or mounts on the MN-BRKT1.
See Figure 29 on page 121 for field wiring. Refer to the MN-PASM2 Preamp
Supervision Module Installation Sheet (P/N 3101950) for installation instructions
and specifications.
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