Studio Technologies 45DC Users Manual
Model 45DC
Dante™ to Dual Party-Line
Intercom Interface
User Guide
Issue 3, March 2016
This User Guide is applicable for serial numbers
M45DC-00151 and later with application firmware 3.1 and later
and Dante firmware 1.2 (Ultimo 2.2.2.5) and later
Copyright © 2016 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50017-0316, Issue 3
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Table of Contents
Revision History ............................................................ 4
Introduction ................................................................... 5
Installation ..................................................................... 9
Configuration ................................................................ 12
Operation ...................................................................... 15
Technical Notes ............................................................. 20
Specifications ................................................................ 25
Model 45DC User Guide Issue 3, March 2016
Studio Technologies, Inc. Page 3
Revision History
Issue 3, March 2016:
1. Documents new configuration that allows the party-line active detection function to be
disabled (added to application firmware version 3.1).
Issue 2, August 2015:
1. Documents enhanced unit identification feature (added to application firmware
version 2.5).
2. Adds improvements to IP address configuration assignment explanation.
Issue 1, January 2015:
1. Initial release.
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Introduction
The Model 45DC Dante™ to Dual Party-Line
Intercom Interface is designed for applications that utilize single-channel analog party-line (PL) intercom technology. The unit
provides two independent single-channel
interfaces that each support one party-line
audio channel. Single-channel party-line
intercom systems are commonly used in
theater, entertainment, and education applications where a simple, reliable, low-cost,
and easy to use solution is desired. Analog
party-line products from Clear-Com® and
ASL are directly compatible with the Model
45DC. The Dante Audio-over-Ethernet media networking technology is used to transport the send and receive audio channels
associated with each of the two party-line
circuits. Two hybrid circuits with automatic
nulling provide excellent audio quality and
high return-loss. (These hybrid circuits are
sometimes referred to as 2-wire to 4-wire
converters.) The Model 45DC is directly
compatible with the latest broadcast and
audio equipment that uses Dante technology. An Ethernet connection is all that’s
required to make the Model 45DC part of a
sophisticated, networked audio system.
A Model 45DC can interconnect with devices such as matrix intercom systems,
DSP processors, and audio consoles. The
Model 45DC is directly compatible with the
RTS ADAM® OMNEO® matrix intercom
network. Alternately, two Model 45DC units
can interconnect by way of the associated
Ethernet network. The Model 45DC can be
powered by Power-over-Ethernet (PoE) or
an external source of 12 volts DC. Two party-line power sources with impedance termination networks can be supplied by the
Model 45DC, allowing connection of two
sets of user beltpacks such as the ClearCom RS-501 and RS-701. A Model 45DC
Figure 1. Model 45DC standard “throw-down” front view
Figure 2. Model 45DC back view
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can also connect with one or two existing
powered and terminated intercom circuits.
Audio level meters provide confirmation
of system performance during setup and
operation. Support for transporting call
light signals between Model 45DC units is
also provided.
Standard connectors are used for partyline intercom, Ethernet, and DC power
interconnections. The Model 45DC’s
enclosure has a “1/2-rack” 1U form factor
and weighs less than two pounds, making
it well suited for use in portable applications. Alternately, using one of the optional
rack-mount front panels, one or two Model
45DC units can be mounted in a single
space (1U) of a standard 19-inch rack
enclosure.
Applications
There are two main ways that the Model
45DC can be used in applications. The
first is to add party-line intercom support
for matrix intercom systems. The second
is to link two stand-alone party-line intercom systems. Ports on matrix intercom
systems that support Dante, such as the
RTS ADAM with OMNEO, can be routed to
the Model 45DC’s Dante receiver (input)
and transmitter (output) channels. The
Model 45DC’s circuitry will then convert
these signals into two single-channel party-line intercom circuits. In this way adding
party-line support to RTS + OMNEO is a
simple task. The Model 45DC can also be
used with matrix intercom systems that
don’t support Dante. An external analogto-Dante interface can be used to convert
analog intercom ports to Dante channels.
For example, the Model 44D Interface
from Studio Technologies is specifically
designed to work with matrix intercom
systems. Once in the digital domain, these
Dante channels can be interconnected
with the Model 45DC’s audio input and
output channels.
Two separate sets of party-line intercom
circuits can easily be interconnected using
two Model 45DC Interfaces. At each end
a Model 45DC is connected to one or two
party-line circuits as well as the Dante
network. The Dante Controller application will then be used to route the audio
channels between the two units. That’s
it — nothing else is required to achieve
excellent performance.
The Model 45DC can also be used to
“bridge” two single-channel party-line
intercom circuits with one 2-channel partyline intercom circuit. This involves using
a Model 45DC for the two single-channel
circuits and one of the Studio Technologies Model 45DR Intercom Interface units
for the 2-channel circuit. The Model 45DR
is the “cousin” of the Model 45DC and
supports one 2-channel party-line intercom circuit rather than two single-channel
circuits. These 2-channel circuits, typically
supported by equipment from RTS, are
commonly used in broadcast applications.
Party-Line Interfaces
The Model 45DC’s two party-line intercom
interfaces are optimized for connection
with two single-channel party-line circuits
and user devices such as those associated with equipment from Clear-Com. (While
the Model 45DC will function in a limited
manner with a 2-channel RTS TW circuit,
the Model 45DR Intercom Interface is the
much-preferred choice.) Each interface
has a party-line active detection function
to ensure that should a beltpack or active party-line circuit not be connected
the Model 45DC’s interface circuitry will
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remain stable. This unique feature makes
certain that objectionable audio signals,
including oscillations and “squeals,” won’t
be sent to other Dante-enabled devices.
A significant capability of the Model
45DC’s two party-line intercom interfaces
is their ability to supply DC power and
200 ohm AC terminations to “create” two
independent intercom circuits. The 28 volt
DC output can power user devices such
as beltpacks. With up to 150 milliamperes
(mA) of current available, a typical entertainment application could connect up to
three RS-501 or five RS-701 beltpacks to
each of the Model 45DC’s two interfaces.
In many applications this can eliminate the
need for an external intercom power supply, thereby reducing total system cost,
weight, and required mounting space. The
power supply outputs are monitored for
over-current and short-circuit conditions.
Under firmware (embedded software)
control the outputs will automatically cycle
off and on to help prevent damage to the
circuitry and connected equipment.
Dante Audio-over-Ethernet
Audio data is sent to and from the Model
45DC using the Dante Audio-over-Ethernet
media networking technology. Audio
signals with a sample rate of 48 kHz and
a bit depth of up to 24 are supported.
Audio receiver (input) and transmitter
(output) channels on associated Danteenabled devices can be assigned to the
Model 45DC using the Dante Controller
software application. This makes selecting
the way in which a Model 45DC fits into a
specific application a simple matter.
Analog Hybrids with Auto
Nulling
Two circuits referred to as “hybrids” interface the Dante input and output channels
with the two party-line interface channels.
The hybrids provide low noise and distortion, good frequency response, and
high return-loss (“nulling”), even when
presented with a wide range of party-line
conditions. Unlike telephone-line (“POTS”)
oriented DSP-based hybrid circuits, the
Model 45DC’s analog circuitry maintains
extended frequency response. With a
passband of 100 Hz on the low end and
8 kHz on the high end, natural-sounding
voice signals can be sent to and received
from a party-line circuit.
The Model 45DC’s sophisticated hybrid
auto nulling function uses a combination
of digital and analog circuitry under microprocessor control to achieve significant
trans-hybrid loss. This return-loss “null” is
achieved by making a series of firmwaredirected adjustments to account for the
resistive, inductive, and capacitive conditions that are present on the connected
party-line cabling and user devices. Whenever one of the Model 45DC’s auto null
buttons is pressed digital circuitry adjusts
the associated hybrid to achieve its maximum return-loss in less than 15 seconds.
While the nulling process is automatic, it
only takes place upon user request. The
resulting null parameters are stored in
nonvolatile memory.
Pro Audio Quality
The Model 45DC’s audio circuitry was
designed in the spirit of professional
audio equipment rather than that found
in typical party-line intercom gear. Highperformance components are used
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throughout, providing low-distortion, lownoise, and high headroom. Using passive
and active filters the frequency response
of the audio channels is limited to nominally 100 Hz to 8 kHz. This range was
selected to provide excellent performance
for human speech while maximizing the
ability of the hybrid circuits to create substantial “nulls.”
Audio Meters
The Model 45DC contains two sets of
5-segment LED level meters. Each set of
two meters displays the level of the signals
being sent to and received from a partyline interface channel. At the time of installation and setup the meters are invaluable
in helping to confirm correct operation.
During normal operation the meters offer
rapid confirmation of audio signals flowing
in to and out of the unit. Additional LED
indicators are also provided on the front
panel, offering a status indication of the
party-line DC power sources, party-line
activity status, and the auto null functions.
Two other LEDs offer a direct indication
of which source is powering the Model
45DC.
Call Light Support
Typical single-channel party-line intercom
circuits provide a call light function by
way of a DC voltage applied to the audio
path. The Model 45DC can detect call light
activity, convert it to a 20 kHz audio tone,
and transport the tone over the Dante
audio path. A Model 45DC unit at the “far
end” will detect the tone and re-generate the call signal as a DC voltage on the
audio path. This allows full “end-to-end”
call light support between two or more
Model 45DC units. It also allows a Model
45DC to send and receive call light status
with an interconnected Model 45DR Dante
to 2-Channel Party-Line Intercom Interface.
The Model 45DR is typically used with the
RTS TW-series of party-line user beltpacks
including the popular BP-325.
Ethernet Data, PoE, and DC
Power Source
The Model 45DC connects to a data network using a standard 100 Mb/s twistedpair Ethernet interface. The physical
interconnection is made by way of a
Neutrik® etherCON RJ45 connector. While
compatible with standard RJ45 plugs,
etherCON allows a ruggedized, locking
interconnection for harsh or high-reliability
environments. The Model 45DC’s operating power can be provided by way of the
Ethernet interface using the Power-overEthernet (PoE) standard. This allows fast
and efficient interconnection with the associated data network. To support PoE power
management, the Model 45DC’s PoE interface reports to the power sourcing equipment (PSE) that it is a class 3 (mid power)
device. The unit can also be powered
using an external source of 12 volts DC.
For redundancy, both power sources can
be connected simultaneously. An internal
switch-mode power supply ensures that all
Model 45DC features, including party-line
intercom circuit power, are available when
the unit is powered by either source. Four
LEDs on the back panel display the status
of the network connection, Dante interface,
and PoE power source.
Simple Installation
The Model 45DC uses standard connectors to allow fast and convenient interconnections. An Ethernet signal is connected
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