CX122 Mixer Zoner User Guide
General Description
The CX122 is a versatile mixer-zoner that can be used with confidence as part of a
professional sound system. The impressive performance and flexible routing options, together
with the remote level control facility make it suitable for a wide range of applications. In
addition, the fire alarm mute facility with emergency microphone circuitry make the unit well
equipped to satisfy local authority and fire department requirements. The front panel controls
are easy to understand and simple to operate and the unit can be confidently operated by
unskilled personnel. All the routing, gain and equalisation controls are positioned on the rear
panel, with the exception of the front panel mounted microphone EQ which have removable
shafts.
Input Routing
The two music inputs,together with the microphone input can be routed to the two output
zones with some flexibility. The microphone and Line 1 inputs are permanently routed to Zone
1 output,and in addition, Line 2 input can be routed to Zone 1 by selecting the switch located
on the rear panel. All three inputs can operate through Zone 2 in any combination by selecting
the respective routing switch on the rear panel.
Music Inputs
Music inputs
The two stereo line inputs have a flat frequency response and are suitable for most music
sources such as compact disc players, tape players and radio tuners etc. Inputs are
unbalanced, using RCA phono sockets and the nominal input sensitivity is 0dBu (775mV)
±12dB with an impedance of 100kΩ.
Gain control
The two stereo line inputs have pre-set gain controls mounted on the rear panel, adjacent to
the input sockets. The range of control is ±12dB. As the nominal input sensitivity is 0dBu
(775mV), the input sensitivity can be varied from -12dBu (195mV) to +12dBu (3.08V) and each
gain control should be set to allow the front panel level controls to have an optimum range of
control.
Front panel level controls
These controls simply set the levels of the music source and the self adhesive labels supplied
with the unit can be positioned above the controls to clearly identify the source.
Priority
Line 1 input has a provision to provide priority over Line 2 input. The priority switch is
positioned on the rear panel adjacent to Line 1 input sockets. When the priority is active, a
signal present on Line 1 will automatically over-ride Line 2. A typical application is where a juke
box signal (Line 1) is required to over-ride the background music signal (Line 2). There is a
delay of approximately 15 seconds before the Line 2 signal is restored. If the factory default
delay of 15 seconds is too long for the application, an internal jumper can be configured for
alternative release times of 6 or 3 seconds.
Microphone Inputs
Mic inputs
One microphone input is provided and the microphone amplifier is an electronically balanced,
transformerless design configured for optimum low noise performance. The input impedance is
greater than 2kΩ and is suitable for microphones in the 200Ω to 600Ω range. The input is via a
gold plated 3 pin XLR type connector with latch and is located on the rear panel. To operate
the channel in the unbalanced mode, it is suggested that pin 3 be connected to the ground
terminal (pin 1) inside the XLR cable plug.
Gain Control
A pre-set gain control is provided adjacent to the input connector. The gain can be adjusted
from 0dB to 60dB of gain. The wide range of gain allows direct connection of high output
devices such as radio microphones without the need for input attenuators. A high overload
margin is maintained at all gain settings.
Front Panel Level Control
This control is provided for the user to set the desired signal level. It is suggested that the gain
control on the rear panel is set at a level where excessive gain cannot be obtained with the
front panel control in the fully clockwise position. Self adhesive labels are provided and if
appropriate can be placed above the level control.
Priority
The microphone input has a switchable priority option. When the microphone is being used
with the priority switched on, any music signal present will be attenuated automatically. Normal
music operation will be restored smoothly after the announcement has been made. The priority
switch is positioned adjacent to the microphone gain control on the rear panel.
Equalisation
Comprehensive equalisation is provided for the microphone signal. The front panel mounted
treble and bass controls have a range of ±10dB at 5kHz and 100Hz respectively and in
addition, a high pass filter operating at 100Hz reduces undesirable low frequency breath blasts
and handling noise. If required, the microphone equalisation control spindles complete with
knob can be removed and the supplied blanking plugs can be fitted to preserve the settings.
Remote Music Mute
When the CX122 is connected to a fire alarm control panel via the remote music mute
connector, an alarm condition will reduce the level of the music signals to allow the alarm
sounders to be heard and in addition, the microphone channel will be routed directly to the two
output zones, allowing the microphone to operate irrespective of the condition of any level
controls or routing switches (including VCA). This allows the microphone to be used to
organise a controlled evacuation. The emergency microphone level can be set internally by
adjusting the pre-set potentiometer PR1.
Zone Outputs
Zone outputs
The two stereo zone outputs are balanced and can operate with loads as low as 600Ω. 3 pole
¼"(6.35mm) jack sockets are used for all outputs. The nominal output level is 0dBu (775mV)
but the CX122 can operate satisfactorily with a wide range of signal levels up to a maximum
output of +20dBu. If you wish to connect any zone output to an unbalanced input, 2 pole jack
plugs should be used.
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