Manual
Model 45DC User Guide Issue 3, March 2016
Studio Technologies, Inc. Page 21
45DC’s Dante connection shouldn’t be a
problem as a digital audio path that has a
48 kHz sample rate can easily transport a
20 kHz signal.
When the Model 45DC detects DC on the
audio path (pin 3 of the back-panel inter-
face connector) it will digitally generate
a 20 kHz tone and mix (sum) it with any
audio signals present on the associated
Dante transmitter (output) channel. Detec-
tion circuits in the Model 45DC’s Dante
receiver (input) audio paths continually
monitor for the presence of a 20 kHz tone.
If this signal is detected (in the digital
domain) it will cause a DC voltage to be
applied to the audio path of the associ-
ated party-line interface circuit. When the
20 kHz signal is no longer present the DC
voltage will be removed. The 20 kHz-to-DC
translation takes place automatically with
no configuration required. This method
is very useful for a number of reasons.
It allows two Model 45DC units that are
interconnected in a point-to-point manner
to transport both audio and call signals
between them. It will also allow the sup-
port of call signals between a Model 45DC
(supporting two single-channel Clear-Com
party-line circuits) and a Model 45DR
(supporting a 2-channel RTS party-line
circuit). And finally it will allow equipment
that’s capable of transporting 20 kHz call
signals associated with RTS party-line cir-
cuits, such as RTS ADAM OMNEO ports,
to send and receive DC-based call signals
associated with single-channel Clear-Com
party-line devices.
Note that digital filters in the Model 45DC’s
firmware prevent essentially all information
above 10 kHz from being sent to the party-
line audio channels. This helps to ensure
that the hybrid circuits provide a “deep”
null as was as keeping the 20 Hz call
signal from each party-line audio path.
Common Ground
The Model 45DC provides two
independent single-channel party-line
intercom interfaces. These interfaces
can be connected to two sets of user
devices, two existing party-line intercom
circuits, two channels from an external
party-line intercom power supply, or any
combination thereof. An important thing
to remember is that the power source and
audio channel connections associated
with the Model 45DC’s two single-channel
party-line interface channels share a
common ground. This is as expected but
does provide one application limitation.
The two interfaces are not intended to
interconnect (bridge) two intercom circuits
that are isolated from each other. If this
is done through the linking of the pin 1
connections on the Model 45DC’s two
3-pin XLR connectors one can expect
hum, noise, or other audio artifacts to be
created. This would be the result of the
potential difference that would typically be
found on two separate party-line intercom
circuits. If this linking with isolation
function is required a product such as the
Clear-Com TW-12C would be necessary.
3-Position Header
An internal 3-position header connector
allows support for an alternate cover. The
cover, purchased as an option, has an
Anton-Bauer QR-Gold battery bracket that
is electrically wired in parallel with
the 4-pin XLR DC input connector. The
header, located on the Model 45DC’s
printed circuit board, is Molex® part
number 22-23-2031. It mates with Molex
housing number 22-01-3037. To make the