MVPA/VPA Amplifier User Manual
Page 5 of 11
21015 V1.1
1.3
Amplifier Sleep Mode
While the system is idle all amplifiers are automatically set in ‘sleep’ mode to
reduce power consumption. This is particularly important while the AC mains
supply has failed and the system is running on internal batteries.
In order to allow the 20Khz surveillance signal through the system, the control
matrix feeds a ‘wake-up’ signal to all power amplifiers. The purpose of this signal
is to command Audix MOSFET PowerBlocs to switch from their very low power
consumption mode (asleep) to their quiescent state (awake). This allows the
surveillance tone to pass through amplifiers without missing the first part of the
signal.
During normal speech announcements or alarms only the amplifiers selected for
broadcast wake-up. In this case the wake-up is initiated by the audio at the input
terminals of each amplifier. This ensures that any amplifiers NOT being used for
broadcast remain in ‘sleep’ mode.
1.4
Amplifiers chassis Front Panel Displays
Faults can be detected and displayed on ‘MVPA’ versions of the amplifier.
1.5
Amplifier Adjustments / Link Settings
A maximum of 4 PowerBlocs can be fitted inside a chassis. A 240W unit is fitted
with 4 PowerBlocs, one of which is a master (MPB260), while three are slave
units (MPB261). The link settings on Master / Slave Blocs are as follows:
Note:
All adjustments are factory set. No further adjustments should be
necessary.
MPB160 Master
VR1
-
Fine Gain Control
VR2
-
Quiescent Current
MPB161 Slave
