CPA240 Configurable Power Amplifier
Page 22 of 35
21031 CPA240 manual V1.31.doc
5.4.2 Amplifier Group Controller & Slave Settings
The amplifiers in a group must be configured as:
•
Group ‘controller’ (one only)
•
Group ‘slave’
Group Controller
One amplifier within a group must be configured as a ‘controller’.
Once configured the ‘controller’ amplifier provides the drive signal to all the other amplifiers
within that group.
Channel 1 volume control on the control frame provides signal level adjustment for the entire
group.
Group Slave
The remaining amplifiers within the group (other than the single ‘controller’) must be configured
as ‘slaves’.
These amplifiers receive their input drive signal from the group controller.
The volume controls for each input channel belonging to the ‘slave’ group are disabled.
Setting Controller or Slave Configuration
There are two ‘Amplifier link’ headers located on the D800 control card (see section 4.1)
With links fitted (factory setting) the amplifier is configured as a ‘controller’.
To configure the amplifier as a ‘slave’ to a controller these links should be removed.
5.4.3 Amplifier Group Gain Trim
To provide maximum power output and prevent damage to the group the open circuit gain of
each amplifier must be matched to within 0.1Volts.
Method:
•
Configure the amplifiers as an amplifier group as described in the previous sections.
•
Disconnect amplifier 100V output system cabling.
•
Connect a suitable test signal to input channel 1 of the group controller i.e. 0dBu @ 1kHz.
•
Check that output 1 of each amplifier within the group (with the volume control set to
maximum) is approximately 100V +/- 5 RMS (if not locate and repair problem).
•
Measure and note channel 1 output of the group controller to two decimal places i.e.
99.35V.
•
Now measure and adjust the second amplifiers output using the trim control located on the
D800 control card to within 0.1V of the group controllers output i.e. 99.35V
•
Repeat of each amplifier in the group.
•
Recheck that the output of each amplifier is within 0.1V of the others.
•
With all amplifiers matched reconnect all output cabling and test system.
If possible before connecting the system cabling, load the amplifier group to prove the maximum
power output is available.
Note: A small drop in the actual power output compared with the calculated output is
expected due to losses to the paralleling process.
