Studio Technologies 45A - Manual (Page 14)

Issue 2, November 2011 Model 45A User Guide
Page 14 Studio Technologies, Inc.
Dual-Channel Intercom Systems
If compatibility with RTS TW-series is
desired the mating connector (one male
or one female) should be wired so that
common is on pin 1, DC with channel 1
audio is on pin 2, and channel 2 audio
is on pin 3. This wiring scheme applies
whether the connected devices are to
be powered by an external source or by
the Model 45A’s internal 2-wire intercom
power source.
Single-Channel Intercom Systems
There are two ways of connecting to the
Model 45A’s 2-wire (PL) intercom con-
nectors when compatibility with Clear-
Com single-channel intercom devices
is desired. The most direct method is to
prepare a male or female 3-pin XLR mat-
ing connector so that common is on pin 1,
power is on pin 2, and audio is connected
on pin 3. With this connection scenario
only audio channel 2, associated with
pin 3 of the Model 45A’s 2-wire party-line
intercom interface, will be utilized. Pin 2,
the Model 45A’s audio channel 1, will only
be used for connecting DC power to the
connected devices. While the audio re-
sources provided by channel 1 will not
be used, the Model 45A can still be used
to supply DC power on pin 2. As previous-
ly mentioned, the maximum current draw
on the 30 volt DC output is 300 milliam-
peres. Alternatively, an external intercom
power supply can support the connected
devices.
In some single-channel 2-wire party-line
intercom system applications it may be
desirable to take full advantage of the two
channels associated with the Model 45A’s
interface. The Model 45A can certainly be
used in this fashion, but an adapter will
need to be prepared. The recommended
connection method is to create an adapter
that “splits” Model 45A’s 2-wire (PL) inter-
com connector into two 3-pin XLR con-
nectors, one for each audio channel. The
adapter should use one female and two
male connectors. Pin 1 of a female 3-pin
XLR intended to mate with the Model 45A
will connect to pin 1 of both 3-pin male
XLR connectors. Pin 2 of the female XLR
will go to pin 3 of the male XLR designated
as channel 1. Pin 3 of the female XLR will
go to pin 3 of the male XLR designated as
channel 2. Refer to Figure 5 for details.
Using this adapter the Model 45A can be
directly interconnected with two Clear-
Com intercom circuits. However, power for
the connected devices must be provided
by external power sources. The Model
45A’s ability to supply intercom power
will not be utilized.
Note: It’s critical that the correct configu-
ration settings be made when using the
Model 45A’s interfaces to support two
independent intercom circuits. Specifically,
the 2-wire power source configuration
DIP switch 2 must be set to its off (down)
position. In addition switch 4, auto termi-
nate disable, must be placed in its on (up)
position. Refer to the Configuration section
of this user guide for details.
Figure 5. Adapter cable wiring diagram