IMPORTANT!
2-2
A1 User Manual
2.1.3. SpeakerID
A built-in SpeakerID circuit ensures that signal can only be connec-
ted to a loudspeaker if it matches the controller module fitted to
the mainframe. When the SpeakerID circuit senses that the correct
loudspeaker is connected to the mainframe output then the internal
power amplifier outputs are fed to the mainframe speaker output
connector(s) and the green ID LED on the controller module front
panel illuminates.
With no cabinet connected, the ID LED remains unlit. If the wrong
type of cabinet is connected the ID LED will flash and the power
amplifier outputs are internally isolated from the mainframe spea-
ker output connector(s).
SpeakerID not only prevents loudspeaker damage it also prevents
hazardous voltages appearing on the exposed pins of the speaker
output connector(s).
Where a mainframe, such as the 1220 System, has two speaker
output connectors these are independently monitored and separa-
tely switched. However, to alert the user, connecting just one
wrong cabinet will mute both output connectors.
2.1.4. 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 A1 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 2.4. (Mainframe installation).
