CXM Technical
MANUAL
14
4.14
PFL Output
A -2dBu PFL output is provided on a stereo pair of phono sockets. This signal is derived
from the PFL and split cue circuits. The output is identical to the signal on the headphone
output though it is not affected by the phones volume control.
4.15
Remote Music Mute
In certain circumstances, there may be a local authority or Fire Service requirement to
mute the Music Signals via a Fire alarm control panel in an alarm condition.
The CXM M2 provides a facility to mute the music signals. The option to mute mic signals
in addition to the music signals is set by means of J2 (see diagram). The mute is
activated by a fully floating pair of contacts in the Fire alarm control panel which close
during an alarm condition. Do not connect any external voltage sources either AC or DC
to the remote music mute connector. Should the alarm panel not have suitable set of
contacts then it is usual to use an auxiliary relay. Do not attempt to modify the fire alarm
circuits unless you are both qualified and authorised to do so.
To indicate that the remote music mute is active, the red LED on the front panel will flash
and any current PFL selection will be cancelled, effectively muting the headphone
amplifier.
Note. It is normal for the music mute to operate for a few seconds when the mixer is
switched on.
4.16
Emergency signal input
This facility is provided so that pre recorded evacuation message systems can be
interfaced to the M2, allowing messages to be broadcast over the main sound re-
enforcement system. It should be noted that it is unlikely that the main sound re-
enforcement system will meet the regulations necessary for such an application and
therefore this facility should only be used to augment an existing, adequate broadcast
system.
The emergency signal input is a 3 pin XLR, with an adjacent gain control to accommodate
signal levels b/- 12dBu. The input impedance is 10kOhms. The signal is directly
routed to the output stages of the main output, the music output and output 2 with an
nominal output level of 0dBu. This facility is NOT present on any other M2 outputs
including the outputs of the zone module CZ1. The signal level is not affected by any of
the front panel controls.
In order to prevent unwanted noise from the equipment connected to this input reaching
the outputs under normal operating conditions the signal can be gated by the remote
music mute. This facility can be selected by means of a jumper J1. The default position
for this jumper is ON. When this facility is enabled the emergency signal is only routed to
the outputs when the remote mute is activated. As the emergency signal is routed to the
main outputs it is strongly recommended that this ‘gated mode’ is used, particularly if the
signal source is either low level, noisy, unbalanced or of questionable integrity. Using this
input without the gate is highly likely to raise the noise levels on the outputs.
4.17
Mono/Sub-bass output
This balanced output facility uses a 3 pole 1/4" jack socket and can be configured on the
PCB to operate as a mono full range main output (see diagram) or as a mono sub-bass
output to drive amplifiers with sub-bass enclosures to enhance the lowest frequencies
within the audio spectrum. The output level is 0dBu and the low pass filter operates below
63Hz. A 2 pole jack plug can be used for unbalanced signals. The factory default setting
is the mono full range output.
