CX335 User Manual v1.0
9
cable can be used when connecting to an unbalanced
destination. Wire the inputs to the source devices using the
convention shown below:
1
2
3
CX335 output
pin 1: ground
pin 2: hot
pin 3: cold
Balanced amplifier input
+
-
pin 1: ground
pin 3: cold
pin 2: hot
Unbalanced amplifier input
(e.g., phonos)
screen: ground
pin: hot
BALANCED CONNECTION
UNBALANCED CONNECTION
1
2
3
1
2
3
CX335 output
pin 1: ground
pin 2: hot
pin 3: cold
External VCA Interface
The External VCA Interface is a 9-pin female Dsub
connector. The pinout is as follows:
PIN
FUNCTION
1
-15 V DC
2
0 V
3
VCA CONTROL IN
4
0 V
5
+15 V DC
6
0 V
7
8
9
1
2
3
4
5
9
8
7
6
+15
VCA IN
0V
-15
CX335 REMOTE LEVEL PINOUT
Connection for remote muting
The External VCA Interface may be wired to external N/O
(normally-open) relay contacts to mute the programme
audio in both channels when the contacts close. This is a
useful feature where it is necessary to mute music in an
emergency situation; in this case, the relay would probably
be part of the building’s fire alarm system.
Use two-core screened cable to connect to the remote
relay as shown:
1
9
8
7
6
5
4
3
2
N/O RELAY
CONTACTS
Note that to achieve maximum attenuation, the relay
contacts should be wired directly to pins 3 and 5 of the
Dsub connecter. In this case, the music level will be reduced
by approx. 60 dB when the external relay closes. Inserting a
resistor in series with pin 5 will reduce the amount by which
the music level drops on relay closure; it may be useful to
“dim” the music level in this way if the audio system includes
a paging facility where the paging signal is routed to the
amplifiers directly (i.e., does not route via the CX335).
RESISTOR VALUE
LEVEL CHANGE
0 ohms (i.e., no resistor)
-60 dB
470 kohms
-20 dB
1 Mohm
-12 dB
Connection for remote volume control
Another application for the External VCA interface is to
connect it to a rotary control (a variable resistor) to allow
the overall audio volume to be adjusted remotely. To achieve
this, wire the connector, using two-core screened cable, as
shown below:
Chassis Ground Terminal
The rear panel of the CX335 is fitted with an Earthing
(Grounding) Terminal [18]. This is provided for protection
purposes; grounding the CX335 is a safety measure to
protect the users of the system. The terminal should be
connected to a convenient earth point in the rack’s mains
distribution system.
