User manual

(5.0E) 2-1
IMPORTANT!
2. P1200A mainframe
The P1200A mainframe is housed in a 3 rack unit high, 353 mm
(13.9") deep, 19" rack mount enclosure. Included in the mainframe
are power supplies for the controller modules and mainframe
electronics, two power amplifiers, monitoring and protection circuits
and the associated display elements.
C-Series and E-Series loudspeaker specific controller modules may
be installed in either of the two mainframe module slots. The
P1200A mainframe can also be fitted with AMP-L or ampMAX
input modules and configured as a conventional stereo amplifier.
All mainframe facilities and functions and those of the controller
modules can be remotely interrogated and altered via the d&b
Remote Interface Bridge (RIB).
2.1. P1200A power amplifiers
The two P1200A mainframe power amplifiers can each deliver 400
W continuous sine wave output power into an 8 ohm load. With a
4 ohms load, the output power increases to 600 W continuous sine
wave. Both these output figures remain valid for at least 30
minutes of operation at ambient temperatures below 24
° C (75 ° F).
A P1200A will normally be operated with speech or music
programme, complex signals where the average power
requirement is below peak power. The P1200A will continue to
operate indefinitely even where the signal has a very low peak to
RMS ratio (Crest factor, see section 2.12.), provided the device is
installed to enable the heat generated to be adequately dissipated.
2.2. Fan
A fan draws in air through a filter behind the rear panel air intake.
The fan speed is governed by the temperature of the output
module heat sink and the momentary output level. This
arrangement ensures a minimum of fan noise since the fan
operates at minimum speed when power demand is low.
The level controlled fan allows greater cooling during louder
passages, thereby allowing fan speed to be reduced still further
during quiet passages preventing background noise interference.
We advise frequent cleaning of the fan filter to ensure good
airflow through the unit. If the filter is visibly dirty, then it should be
cleaned or replaced. Never operate the P1200A without a filter.
Dust deposits, especially combined with damp conditions, could
cause the mainframe to malfunction.
When setting up the mainframe, do not block or cover the rear
panel air intake or the vents on the front panel of the mainframe.
See also section 2.11. (Mainframe installation).