CX261 Installation and User Guide v1.5
19
Music level
Music level in a zone may be varied over its full range by applying a DC voltage of between 0 and +10 V to pin 2, the 0 V reference
being connected to Pin 1. 0 V on pin 2 corresponds to full level and +10 V will produce maximum attenuation. Between these
two voltages, the rate of attenuation is approximately 165 mV/dB.
Note that there is an internal 4k7 “pull-up” resistor between pin 2 and the in12 V rail. If pin 2 is left “floating”, this
pull-up will result in full attenuation. The output impedance of the control voltage source should be low enough to overcome
the effect of this resistor.
Music source
Music source for a zone may be controlled by applying various DC voltages of between 0 and +10 V to pin 3, the 0 V reference
being connected to pin 1. 0 V at pin 3 will select Line input 6 and b7.5 and +9 V will select Line input 1. The other line
inputs will be selected with intermediate voltages. Taking pin 3 above +9 V will deselect all inputs, making the zone effectively
‘off’ for music.
The table below lists the DC voltages required at pin 3 to select each line input. The third column is the value of a resistor which
should be connected between pins 1 and 3 to permanently ‘force’ a zone to a particular line input.
INPUT
DC VOLTAGE
RESISTOR VALUE
OFF
>+9.0 V
Line 1
+7.5 V
16k
Line 2
+6.0 V
11k
Line 3
+4.5 V
6k8
Line 4
+3.0 V
3k9
Line 5
+1.5 V
1k8
Line 6
0 V
short-circuit
Note that there is an internal 15k “pull-up” resistor between pin 3 and the in12 V rail. If pin 3 is left “floating”, this
pull-up will cause ‘OFF’ to be selected. The output impedance of the control voltage source should be low enough to overcome
the effect of this resistor.
Fitting loudspeaker EQ cards
The CX261 is compatible with various popular installed-sound loudspeakers; a single-channel loudspeaker equalisation module
may be fitted in the left or right channel of the main output (either or both) to optimise the frequency response of the channel
to the loudspeaker type being used. Note that there is no provision for fitting an equalisation module to the MOH/Auxiliary
output.
Please check the Cloud website (
www.cloud.co.uk/accessories
) for makes and models of loudspeakers for which EQ cards are
available.
1. Switch off the power and isolate the CX261 from the mains.
2.
Remove the top panel (6 screws).
3. Plug the equalisation module onto its connector; note that the connector has two notches on one side which engage with
lugs on the module’s mating connector to ensure correct orientation.
4. Replace the top panel.
See the Appendix section “PCB jumper locations and settings” at page 20 for further details. Replace the top cover with the
original screws after fitting.