- 3 -
Issue 1
Fitting Input (IMP) and Mixer (MS) Modules
Input Pre-amplifiers, Mixer Stages and
lnfill (BP) Front Panels are inserted into
the front of the amplifier by slackening
the four self-tapping screws (two on
either side) which hold the top
aluminium extrusion in place. Raise
the front of the extrusion and insert the
module by locating bottom tab on
module into the bottom extrusion and
press the PCB into the edge connector.
When all Pre-amplifiers, Mixer Stage
and lnfill Panels are in position re-
locate top extrusion and secure. See
diagram below.
Prior to inserting inputs ensure that the
dual in line switch has been adjusted in
accordance with the notes on later
pages - see relevant IMP data.
All input modules have detachable
knobs and spindles, thus any input
module can be converted to a pre-set mode.
NOTE: Ensure that AC and DC power are disconnected before removing or inserting modules.
Rear Panel Connections
See relevant IMP or MS instruction manual for connection details.
MS and PA Dual Bus Lines
The input mother board on all mixer amplifiers has 2 Bus Lines, which are selectable via the DIL
switch on most IMP modules.
Audio routed on the MS Bus passes through tone and gain controls on the MS stage.
Audio routed on the PA Bus pass directly to the power amplifier stage via a level raising amplifier on
the mother board itself.
This bus is normally used to route critical audio signals such as 20 KHz for line surveillance,
emergency announcements and alarm signals.
The following IMP modules feed this bus automatically IMP20, 21, and 33.
An MS1 need not be fitted if the MS Bus is not required.
If any of the IMP modules are configured to use the MS bus, then an MS stage must be fitted.
