Studio Technologies 545DR Intercom Interface User Guide

**Studio Technologies 545DR Intercom Interface User Guide

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Introduction

The Model 545DR Intercom Interface allows 2- channel analog party-line (PL) intercom circuits and user devices to be incorporated into Dante® audio-over- Ethernet applications. Analog party-line intercom is commonly used in broadcast, corporate, and commercial applications where a simple, reliable, easy to use solution is desired. Dante has become a major method of interconnecting audio signals and various devices using standard Ethernet networks.

The Model 545DR directly supports both analog PL and Dante, providing excellent performance in bot domains. The popular RTS® TW 2-channel analog intercom circuit technology is directly compatible with the Model 545DR. The Dante audio-over-Ethernet media networking technology is used to transport the two send and two receive audio channels associated with this type of party- line circuit. The Model 545DR’s two hybrid circuits with automatic nulling action provide good separation of send and receive audio with high return loss and excellent audio quality. (These hybrid circuits are sometimes referred to as 2-wire to 4-wire converters.) The Model 545DR’s digital audio signals are compatible with all broadcast and audio equipment that utilizes Dante technology.
An Ethernet connection is all that’s required to make the Model 545DR part of a sophisticated, networked audio system.

The Model 545DR can interconnect with Dante supported devices such as matrix intercom systems, digital audio processors, and audio consoles. The unit is directly compatible with the RTS ADAM® OMNEO® matrix intercom network. Alternately, two Model 545DR units can be interconnected by way of an associated Ethernet network. The Model 545DR can also become part of a PL intercom system when used in conjunction with devices such as the Models 5421 and 5422A Dante Intercom Audio Engine units from Studio Technologies. In this way, an analog party-line intercom circuit can become part of a highperformance digital party-line intercom deployment.

The Model 545DR can be powered by Power-overEthernet (PoE) or an external source of 12 volts DC. The unit can provide a party-line power source and impedance termination networks to allow direct connection of 2-channel user beltpacks. This ability allows support for connection of up to three of the popular RTS BP-325 beltpacks. A Model 545DR can also connect with an existing powered and terminated PL intercom circuit. The unit provides four audio level meters that help to confirm system performance during setup and operation. Support for transporting call light signals between two Model 545DR units, as well as between a Model 545DR and other compatible units, is also provided.

The STcontroller software application can be used to real-time monitor and control several Model 545DR operating parameters. In addition, two configuration settings are performed using the application. Versions of STcontroller are available that are compatible with the Windows® and macOS® operating systems. They are available, free of charge, from the Studio Technologies’ website. Standard connectors are used for Model 545DR party-line (PL) intercom, Ethernet, and DC power interconnections. Set up and configuration of the Model 545DR is simple. A Neutrik® etherCON RJ45 jack is used to interconnect with a standard twisted-pair  Ethernet port associated with a local-area network (LAN). This connection can provide both PoE power and bidirectional digital audio. LEDs provide status indications of the Ethernet and Dante connections.

The unit’s lightweight aluminum enclosure is intended for desk or tabletop use. Optional mounting kits allow one or two Model 545DR units to be mounted in one space (1U) of a standard 19-inch rack enclosure.

**Figure 1. Model 545DR Intercom Interface front and back views

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Applications

There are three main ways that the Model 545DR can be used in applications: connecting analog party-line (PL) intercom circuits to Dante-based intercom applications, adding party-line (PL) intercom support for matrix intercom systems, and linking two stand-alone analog party-line intercom circuits.

The Model 545DR’s Dante transmitter (output) and receiver (input) channels can be connected to Dante-based digital PL intercom circuits. These circuits would typically be created using devices such as the Studio Technologies’ Models 5421 or 5422A Dante Intercom Audio Engines. This would allow legacy analog equipment to become part of contemporary all-digital intercom applications. The resultant audio quality for both the analog and Dante-base PL should be excellent.

Ports on matrix intercom systems that support Dante, such as the RTS ADAM with OMNEO, can be routed to the Model 545DR’s Dante transmitter (output) and receiver (input) channels. The Model 545DR’s circuitry will then convert these signals into a 2-channel analog party-line intercom circuit. In this way, adding analog party-line support to RTS + OMNEO is a simple task. The Model 545DR can also be used with matrix intercom systems that don’t support Dante. An external analog-to-Dante interface can be used to convert analog intercom ports to Dante channels. For example, the Model 544D Audio Interface from Studio Technologies is specifically designed to work with matrix intercom systems. Once in the Dante digital domain, these channels can be interconnected with the Model 545DR’s Dante input and output channels.

Two separate analog party-line (PL) intercom circuits can easily be interconnected using two Model 545DR Interfaces. A Model 545DR is connected to each PL circuit as well as to the Dante network. The Dante Controller software application will then be used to route (subscribe) the audio channels between the tw units. (The physical distance between units will only be limited by the deployment of the LAN’s subnet.)

That’s it — nothing else is required to achieve excellent performance.

The Model 545DR can also be used to “bridge” a 2-channel party-line intercom circuit with one or two single-channel party-line intercom circuits. This involves using a Model 545DR with the 2-channel circuit and one or two of the Studio Technologies’ Model 545DC Intercom Interface units that support single- channel party-line intercom circuits. The Model 545DC is a “cousin” of the Model 545DR and supports two single-channel party-line intercom circuits rather than one 2-channel circuit. These single-channel circuits, typically supported by equipment from ClearCom®, are commonly used in theatrical and entertainment applications.

Party-Line Interface

As previously discussed, the Model 545DR’s party-line intercom interface is optimized for connection with 2-channel party-line intercom circuits and user devices such as the TW-series from RTS.

In addition, other industry-standard single- and 2-channel party-line intercom circuits and user devices, including those from Clear Com, are compatible.

(While the Model 545DR will function in a limited manner with single-channel Clear-Com circuits, the Model 545DC Intercom Interface unit is a muchpreferred choice for that.) A party line active detection function ensures that should a user beltpack or active party-line intercom circuit not be connected the Model 545DR’s interface circuitry will 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 545DR’s party-line interface is its ability to supply DC power and 200 ohms AC terminations to “create” an intercom circuit. The 29 volt output can power a moderate number of devices such as beltpacks. With up to 240 milliamperes (mA) of current available, a typical broadcast application which uses up to three BP-325 beltpacks can be supported. In many applications, this can eliminate the need for an external intercom power supply, reducing total system cost, weight, and required mounting space. The power supply output is monitored for over-current and short-circuit conditions.

Under firmware (embedded software) control the output 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 545DR 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 transmitter (output) and receiver (input) channels on associated Dante- enabled devices can be assigned to the Model 545DR using the Dante Controller application. This makes it simple to select the way in which a Model 545DR fits into a specific application.

Analog Hybrids with Auto Nulling
Circuits referred to as “hybrids” interface the Dante transmitter (output) and receiver (input) channels with the two channels of the party-line circuit. 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 545DR’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 545DR’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 firmware-directed adjustments to account for the resistive, inductive, and capacitive conditions that are present on the connected party- line cabling and user devices.

Whenever the Model 545DR’s auto null button is pressed, or the STcontroller application is used, digital circuitry adjusts the hybrids to achieve their 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 non-volatile memory.

Pro Audio Quality
The Model 545DR’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 throughout, providing low-distortion, low- noise, and high headroom. Using 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.” Moreover, the Model 545DR’s party-line intercom power source offers a unique level of performance; its ability to deliver power while maintaining audio quality is simply unmatched.

Audio Meters
The Model 545DR 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 party-line 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 Model 545DR unit.

Status Display
LED indicators are provided on the Model 545DR’s front panel, offering a status indication of the party-line (PL) power source, party-line (PL) activity status, and the two auto null functions. Two other LEDs offer a direct indication of what power source or sources are connected to the Model 545DR. The STcontroller application provides a real-time “virtual” status displa of the unit’s PL power source, PL activity, and auto null functions.

Call Light Support

RTS TW-compatible party-line intercom user devices, such as the BP-325 beltpack, provide a call light function using a 20 kHz square-wave signal that is added to the designated audio path. To achieve optima audio performance this signal, along with essentially all content above 10 kHz, is normally removed from the audio signal that is sent out the Model 545DR’s Dante transmitter (output) channels. It’s also removed from the audio signal that arrives by way of the Model 545DR’s Dante receiver (input) channels. While the result is excellent party-line talk audio, 20 kHz call light signals are prevented from being directly sent to and received from multiple Model 545DR units. A Model 545DR feature overcomes this limitation, detecting the call light activity and re-generating it (again as a 20 kHz tone) in the applicable audio path. This allows reliable “end-to-end” call light support between two Model 545DR units. It also allows a Model 545DR to send and receive call light status signals with an interconnected Model 45DC or Model 545DC Intercom Interface. These units are typically used with ClearCom party-line user beltpacks including the popular RS-501 and RS-701.

Ethernet Data, PoE, and DC Power Source

The Model 545DR connects to a local area data network (LAN) using a standard 100 Mb/s twisted-pair Ethernet interface. The physical interconnection is made by way of a Neutrik etherCON RJ45 jack. While compatible with standard RJ45 plugs, an etherCON jack allows a ruggedized and locking interconnection for harsh or high-reliability environments. The Model 545DR’s operating power can be provided by way of the Ethernet interface using the Power-over-Ethernet (PoE) standard. This allows fast and efficient interconnection with the associated data network. To support PoE power management, the Model 545DR’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 545DR 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 545DR uses standard connectors to allow fast and convenient interconnections. An Ethernet signal is connected using a Neutrik etherCON RJ45 jack. If Power-over-Ethernet (PoE) is available operation will commence immediately.

An external 12 volts
DC power source can also be connected by way of a 4-pin female XLR connector. Party-line intercom connections can be made using 3-pin male and female XLR connectors. The Model 545DR is housed in a rugged yet lightweight aluminum enclosure that is designed to be “field tough.” It can be used as a standalone portable unit, supporting what’s known in the broadcast world as “throw-down” applications.
Rack-mounting option kits are available that allow one or two Model 545DR units to be mounted in one space (1U) of a standard 19-inch rack enclosure.

Future Capabilities and Firmware Updating

The Model 545DR was designed so that its capabilities and performance can easily be enhanced in the future. A USB receptacle, located on the Model 545DR’s back panel, allows the application firmware (embedded software) to be updated using a USB flash drive. To implement its Dante interface the Model 545DR uses the UltimoX2™ integrated circuit from Audinate. The firmware in this integrated circuit can be updated via the Ethernet connection helping to ensure that its capabilities remain up to date.

Getting Started

In this section, a location will be selected for the Model 545DR. If desired, an optional installation kit will be used to mount the unit into a panel cutout, wall surface, or equipment rack. Signal interconnections will be made using the unit’s back-panel connectors. Connections to an existing party-line intercom circuit or one or more party-line user devices will be made using one of the 3-pin XLR connectors. An Ethernet data connection, typically which includes Power-over-Ethernet (PoE) capability, will be made using a standard RJ45 patch cable. A 4-pin XLR connector allows connection of a 12 volts DC power source.

What’s Included
Included in the shipping carton are a Model 545DR Intercom Interface and instructions on how to obtain an electronic copy of this guide. An optional installation kit allows a Model 545DR to be mounted in a rectangular opening in a tabletop or attached to a flat surface. If one or two Model 545DR units are going to be mounted in a 19-inch equipment rack then having another of the optional rack-mount installation kits is required. If an installation kit was purchased it would typically have been shipped in a separate carton. As a device that can be powered by Power-over-Ethernet (PoE) or an external source of 12 volts DC, no power source is included. (A compatible power supply, the Studio Technologies’ PS-DC-02, is available as an option.)

Locating the Model 545DR
Where to locate a Model 545DR will depend on being able to access the associated party-line circuit or wiring provided for the desired user devices. In addition, the unit must be located such that connection to the designated Ethernet signal is also possible. The Model 545DR is shipped as a self- contained “throwdown” unit suitable for portable use or placement in a semi- permanent location. Installed on the bottom of the chassis are screw-affixed “bump on” protectors (also known as rubber “feet”). These are useful if the unit is going to be placed on a surface where scratching of either the Model 545DR’s enclosure or the surface material could take place. However, if applicable the “feet” can be removed when installation in a panel cutout, wall mount, or rack enclosure is going to be performed.

Once the unit’s physical location has been established its assumed that the twisted-pair Ethernet cabling will be within 100-meters (325-feet) of the Ethernet port on an associated network switch. It this is not the case, then the overall length limit can be overcome by using a fiber-optic interconnection between the Model 545DR’s-related-Ethernet switch and another Ethernet switch that’s part of the application’s local-area-network (LAN). With a fiber interconnect there’s no reason why a Dante-supported LAN can’t be distributed over many miles or kilometers.

Mounting Options
Panel Cutout or Surface Mounting One Model 545DR Unit
Installation kit RMBK-10 allows one Model 545DR to be mounted in a panel cutout or onto a flat surface.
The kit contains two standard-length brackets and four 6-32 thread-pitch Phillips-head machine screws. Refer to Appendix B for a visual explanation.

Get ready to install the kit by first removing the four machine screws and associated “bump on” protectors from the bottom of the Model 545DR’s chassis. They are removed using a #1 Phillips screwdriver. Store the four machine screws and four “bump on” protectors for possible later use.

To prepare the unit to mount in a cutout or other opening in a panel, use a #2 Phillips screwdriver and two 6-32 machine screws to attach one of the standard-length brackets onto the left side (when viewed from the front) of the Model 545DR’s enclosure. Orient the standard-length bracket such that its front is parallel to the Model 545DR’s front panel. The screws will mate with the threaded fasteners that can be seen on the side of the Model 545DR’s enclosure, near the front of the unit. Using two additional 6-32 machine screws, attach the other standard-length bracket onto the right side of the Model 545DR’s enclosure.

Once the two standard-length brackets have been installed the Model 545DR will be ready to be mounted into an opening. Secure the unit into the top left and right edges of the opening using two mounting screws per side.

To prepare the unit to be mounted onto a flat surface simply requires the standard-length brackets be attached to the Model 545DR at 90 degrees from how they are mounted for use in a panel cutout. Use a #2 Phillips screwdriver and two 6-32 machine screws to attach one of the standard-length brackets onto the left side (when viewed from the front) of the enclosure.

Orient the bracket such that its front is parallel with the top surface of the Model 545DR’s enclosure. The screws will mate with the threaded fasteners that can be seen on the side of the Model 545DR’s enclosure, near the front of the unit. Following the same orientation, use two additional 6-32 machine screws to attach the other standard-length bracket onto the right side of the Model 545DR’s enclosure.

Once the two standard-length brackets have been installed the Model 545DR will be ready to be mounted onto a flat surface. Secure the unit to the surface using two mounting screws per side.

Left- or Right-Side Rack Mounting One Model 545DR Unit
Installation kit RMBK-11 allows one Model 545DR to be mounted in the left or right side of one space (1U) of a standard 19-inch rack enclosure. The kit contains one standard-length bracket, one long-length bracket, and four 6-32 thread-pitch Phillips head machine screws. Refer to Appendix C for a visual explanation.

Get ready to install the kit by removing the four machine screws and associated “bump on” protectors from the bottom of the Model 545DR’s chassis. They are removed using a #1 Phillips screwdriver. Store the four machine screws and four “bump on” protectors for possible later use.

To prepare the unit to mount in the left side of a rack enclosure, use a #2 Phillips screwdriver and two 6-32 machine screws to attach the standard-length bracket onto the left side (when viewed from the front) of the enclosure. The screws will mate with the threaded fasteners that can be seen on the side of the Model 545DR’s enclosure, near the front of the unit.
Using two additional 6-32 machine screws, attach the long-length bracket onto the right side of the Model 545DR’s enclosure.

To prepare the unit to mount in the right side of a rack enclosure, use a #2 Phillips screwdriver and two 6-32 machine screws to attach the long-length bracket onto the left side of the enclosure. Using two additional 6-32 machine screws, attach the standard-length bracket onto the right side of the Model 545DR’s enclosure.

Once the standard-length and long-length brackets have been installed the Model 545DR will be ready to be mounted into the designated equipment rack. One space (1U or 1.75 vertical inches) in a standard 19-inch equipment rack is required. Secure the unit into the equipment rack using two mounting screws per side.

Rack-Mounting Two Model 545DR Units
Installation kit RMBK-12 is used to allow two Model 545DR units to be mounted in one space (1U) of a standard 19-inch equipment rack. The kit can also be used to mount one Model 545DR and one other Studio Technologies’ product that is compatible with the RMBK-12, such as the Model 5421 Dante Intercom Audio Engine. The RMBK-12 installation kit contains two standard-length brackets, two joiner plates, eight 6-32 thread-pitch Phillips-head machine screws, and two 2-56 thread-pitch Torx™ T7 thread-forming machine screws. Refer to Appendix D for a visual explanation.

Get ready to install the kit by removing the four machine screws and associated “bump on” protectors from the bottom of each chassis. They are removed using a #1 Phillips screwdriver. Store the eight machine screws and eight “bump on” protectors for possible later use.

With assistance from a #2 Phillips screwdriver, use two of the 6-32 machine screws to attach one of the standard-length brackets onto the left side (when viewed from the front) of one of the Model 545DR units. The screws will mate with the threaded fasteners that can be seen on the side of the Model 545DR’s enclosure, near the front of the unit. Using two more of the 6-32 machine screws, attach one of the joiner plates onto the right side of that same Model 545DR unit.

Again using two of the 6-32 machine screws, attach the second standard-length bracket onto the right side of the second Model 545DR or another compatible unit. Using the final two 6-32 machine screws, attach the second joiner plate onto the left side of the second Model 545DR or other compatible unit with an orientation of 180 degrees from the way in which the first plate was installed.

To complete the assembly, “join” the units together by sliding each joiner plate through the other. The grooves in each joiner plate will carefully align with each other and form a relatively tight bond. Line up the two units so that the front panels form a common plane. With the aid of a Torx T7 screwdriver, use the two 2-56 Torx machine screws to secure the two joiner plates together. The screws should fit snugly into the small openings formed by the mating of the two joiner plates.

The 2-unit assembly is now ready to be mounted into the designated equipment rack. One space (1U or 1.75 vertical inches) in a standard 19-inch equipment rack is required. Secure the assembly into the equipment rack using two mounting screws per side.

Center Rack Mounting One Model 545DR Unit
Installation kit RMBK-13 allows one Model 545DR to be mounted in the center of one space (1U) of a standard 19-inch rack enclosure. The kit contains two medium-length brackets and four 6-32 thread-pitch Phillips-head machine screws. Refer to Appendix E for a visual explanation.

Get ready to install the kit by removing the four machine screws and associated “bump on” protectors from the bottom of the Model 545DR’s chassis. They are removed using a #1 Phillips screwdriver. Store the four machine screws and four “bump on” protectors for possible later use.

To prepare the unit to mount in the center of a rack enclosure, use a #2 Phillips screwdriver and two 6-32 machine screws to attach one of the medium- length brackets onto the left side (when viewed from the front) of the enclosure. The screws will mate with the threaded fasteners that can be seen on the side of the Model 545DR’s enclosure, near the front of the unit.

Using two additional 6-32 machine screws, attach the other medium-length bracket onto the right side of the Model 545DR’s enclosure.
Once the two medium-length brackets have been installed the Model 545DR will be ready to be mounted into the designated equipment rack. One space (1U or 1.75 vertical inches) in a standard 19-inch equipment rack is required. Secure the unit into the equipment rack using two mounting screws per side.

Ethernet Connection with PoE
An Ethernet connection that supports 100BASE-TX (100 Mb/s over twisted-pair) is required for Model 545DR operation. A 10BASE-T connection is not sufficient; a 1000BASE-T (GigE) connection is not supported unless it can automatically “fall back” to 100BASE-TX operation. An Ethernet connection that supports Power-over-Ethernet (PoE) is preferred as it will also provide operating power for the Model 545DR. To support a PoE Ethernet switch (PSE) that includes power management capability the Model 545DR will enumerate itself as a PoE class 3 device.

A 100BASE-TX Ethernet connection is made by way of a Neutrik etherCON RJ45 jack that is located on the back panel of the Model 545DR. This allows connection by way of a cable mounted etherCON plug or a standard RJ45 plug. A crossover cable will never be required as the Model 545DR’s Ethernet interface supports auto MDI/MDI-X. Per the Ethernet standard, the Ethernet Switch-to- Ethernet Device length limitation for twisted-pair cabling is 100-meters (325-feet).

External 12 Volt DC Input
An external source of 12 volts DC can be connected to the Model 545DR by way of a 4-pin male XLR connector which is located on the back panel. While the stated requirement for the external source is nominally 12 volts DC, correct operation will take place over a 10 to 18 volts DC range. The Model 545DR requires a maximum current of 1.0 amperes for correct operation. The DC source should be terminated on a 4-pin female XLR connector with pin 1 negative (–) and pin 4 positive (+); pins 2 and 3 should remain unterminated. Purchased as an option, the PS-DC-02 power supply, available from Studio Technologies, is directly compatible. Its AC mains input allows connection to 100-240 volts, 50/60 Hz and has a 12 volts DC, 1.5 amperes maximum output that is terminated on a 4-pin female connector.
As previously discussed, an Ethernet connection that provides Power-over- Ethernet (PoE) can serve as the Model 545DR’s power source. Alternately, an external 12 volts DC source can be connected. For redundancy, both PoE and an external 12 volts DC source can be connected at the same time. If both PoE and an external 12 volts DC source are connected, power will be drawn only from the PoE supply. If the PoE source becomes inoperative the 12 volts DC source will provide the Model 545DR’s power with no interruption in operation. (Of course, if both PoE and Ethernet data support are lost that is a very different situation!)

Party-Line Intercom Connections

The Model 545DR’s party-line intercom interface is designed to function in two distinct ways. It can be connected to a “powered” broadcast-standard 2-channel party-line intercom circuit. Alternately, it can be connected directly to party-line intercom user devices. A 2-channel party-line intercom circuit, such as one associated with TW-series equipment from RTS, will have DC power and two audio channels on a 3-pin XLR connector. These connectors will be wired such that common is on pin 1 and 28 to 32 volts DC is on pin 2. Channel 1 audio is superimposed on the DC present on pin 2 while channel 2 audio is present on pin 3. The party-line intercom circuit will also include two impedance-generating networks that provide 200 ohms audio (AC) loads from pin 2 to pin 1 and from pin 3 to pin 1. When the Model 545DR’s party-line interface is connected to an existing intercom circuit it will act, from an audio standpoint, as a standard party-line intercom user device. It won’t draw (nor supply) any DC power.

The Model 545DR’s party-line interface can also serve to create a “mini” 2-channel intercom circuit. It can provide a 29 volts DC, 240 milliamperes maximum, power source along with two 200 ohms impedance generators. This relatively modest amount of current will allow a limited number of 2-channel intercom user devices to be directly connected. Many broadcast applications use the popular RTS BP-325 user beltpack and the Model 545DR’s intercom interface can directly support up to three of them. Wiring from the Model 545DR’s intercom interface to one or more of the BP-325 devices requires that a 1-to-1, 2-to-2, 3-to-3 wiring scheme on associated 3-pin XLR connectors be maintained.

For convenience, the party-line intercom circuit and/or user devices can connect to the Model 545DR by way of the male and female 3-pin XLR connectors that are located on the unit’s back panel. The two connectors are wired in parallel (“multed”) and provide access to the identical signals.

Compatibility with Single-Channel Intercom Systems
As previously discussed, the Model 545DR is designed to directly support 2-channel party-line intercom circuits and user devices. Applications that involve single-channel party-line intercom circuits and user devices (typically associated with products from Clear-Com) can also be supported. These circuits and devices typically utilize common on pin 1, power on pin 2, and audio on pin 3. When this kind of intercom circuit is directly connected to the Model 545DR’s intercom interface only channel 2 will be active; channel 1 would not be utilized.

A better means to support these single-channel party-line intercom circuits and user devices is to use the Studio Technologies’ Model 45DC or Model 545DC Intercom Interface units. They are “cousins” of the Model 545DR and optimized for single-channel party-line intercom applications. Rather than providing a single 2-channel interface, these units provide two single-channel-optimized party-line intercom interfaces. Detailed information about the units will be available on the Studio Technologies’ website (studio-tech.com).

Dante Configuration

To integrate the Model 545DR into an application requires that a number of Dante-related parameters be configured. These configuration settings will be stored in non-volatile memory within the Model 545DR’s Dante interface circuitry. Configuration will typically be done using the Dante Controller software application which is available for download free of charge at audinate.com. Versions of Dante Controller are available to support the Windows and macOS personal computer operating systems. The Model 545DR uses the UltimoX2 2-input/2-output integrated circuit to implement its Dante interface. The Model 545DR’s Dante interface is compatible with the Dante Domain Manager (DDM) software application.

Audio Routing
Two Dante transmitter (output) channels on associated equipment should be routed (subscribed) to the Model 545DR’s two Dante receiver (input) channels.
The Model 545DR’s two Dante transmitter (output) channels should be routed (subscribed) to two Dante receiver (input) channels on associated equipment.
This achieves audio interconnection of the Model 545DR’s two party-line intercom channels with the Dante network and associated Dante device or devices.

Within Dante Controller a “subscription” is the term used for routing a transmitter channel or flow (a group of up to four output channels) to a receiver channel or flow (a group of up to four input channels). The number of transmitter flows associated with an UltimoX2 integrated circuit is limited to two. These can either be unicast, multicast, or a combination of the two. If the Model 545DR’s transmitter (output) channels need to be routed using more than two flows it’s possible that an intermediary device, such as the Studio Technologies’ Model 5422A Dante Intercom Audio Engine, can be used to “repeat” the signals.

Model 545DR units will typically be used in one of two common configurations: “point-to-point” or in association with other Dante-enabled equipment. The first configuration will utilize two Model 545DR units that “work” together to link two physical locations. At each location there will either be an existing party-line intercom circuit or a set of user intercom devices (such as beltpacks). The two Model 545DR units will  operate “point-to-point,” interconnecting by way of the associated Ethernet network. To implement this application is very simple. The From PL Ch1 channel on each unit would be routed (subscribed) to the To PL Ch1 channel on the other unit. And the From PL Ch2 channel on each unit would be routed (subscribed) to the To PL Ch2 channel on the other unit.
The other typical application will have one Model 545DR connected to an existing party-line intercom circuit or a set of user devices. Then the unit’s Dante audio channels would be routed (subscribed) to the Dante transmitter (output) and receiver (input) channels on associated Dante-enabled equipment.
An example of this equipment could be the RTS ADAM matrix intercom system that provides Dante interconnection capability using its OMNEO interface card. The audio channels on the Model 545DR would be routed (subscribed) to and from audio channels on the OMNEO card. Other equipment that supports Dante, such as audio consoles or audio interfaces (Dante-to-MADI, Dante-to-SDI, etc.), can have their audio channels routed (subscribed) to and from a Model 545DR.

Device and Channel Names
The Model 545DR has a default Dante device name of ST-545DR- followed by a unique suffix. (A technical reason prevents the default name to be the preferred ST-M545DR- (an “M” included). But that can be added by the user.) The suffix identifies the specific Model 545DR that is being configured. The suffix’s actual alpha and/or numeric characters relate to the MAC address of the unit’s UltimoX2 integrated circuit. The unit’s two Dante transmitter (output) channels have default names of From Ch1 and From Ch2. The unit’s two Dante receiver (input) channels have default names of To PL Ch1 and To PL Ch2. Using Dante Controller, the default device and channel names can be revised as appropriate for the specific application.

Device Configuration
The Model 545DR only supports an audio sample rate of 48 kHz with no pull-up /pull-down values available. The audio encoding is fixed for PCM 24. Device Latency and Clocking can be adjusted if required but the default value is typically correct.

Network Configuration – IP Address
By default, the Model 545DR’s Dante IP address and related network parameters will be determined automatically using DHCP or, if not available, the link- local network protocol. If desired, Dante Controller allows the IP address and related network parameters to be manually set to a fixed (static) configuration. While this is a more-involved process than simply letting DHCP or link-local “do their thing,” if fixed addressing is necessary then this capability is available. In this case, it’s highly recommended that a unit be physically marked, e.g., directly using a permanent marker or “console tape,” with its specific static IP address. If knowledge of a Model 545DR’s IP address has been misplaced there is no reset button or other method to easily restore the unit to a default IP setting.

AES67 Configuration – AES67 Mode
The Model 545DR can be configured for AES67 operation. This requires the AES67 Mode to be set for Enabled. By default, AES67 mode is set for Disabled.
Note that in the AES67 mode the Dante transmitter (output) channels will function in multicast; unicast is not supported.

Model 545DR Clocking Source
While technically the Model 545DR can serve as a Leader clock for a Dante network (as can all Dante-enabled devices) in virtually all cases the unit will be configured to receive “sync” from another device. As such, the check box for Preferred Leader associated with the Model 545DR would not want to be enabled.

Model 545DR Configuration

The STcontroller software application is used to configure two Model 545DR functions, call light support and PL active detection. (STcontroller also allows real-time display and control of other  Model 545DR functions.

These functions will be detailed in the Operation section.) No DIP switch settings or other local actions are used to configure the unit. This makes it imperative that STcontroller be available for convenient use on a personal computer that’s connected to the related LAN.

Installing STcontroller
STcontroller is available free of charge on the Studio Technologies’ website (studio-tech.com). Versions are available that are compatible with personal computers running selected versions of the Windows and macOS operating systems. If required, download and install STcontroller onto a designated personal computer. This personal computer must be on the same local area network (LAN) and subnet as the one or more Model 545DR units that are to be configured. Immediately after starting STcontroller the application will locate all the Studio Technologies’ devices that it can control. The Model 545DR units that can be configured will appear in the device list. Use the Identify command to allow easy recognition of a specific Model 545DR unit. Double-clicking on a device name will cause the associated configuration menu to appear. Review the current configuration and make any changes that are desired.

Configuration changes made using STcontroller will be immediately reflected in the unit’s operation; no Model 545DR reboot is required. As an indication that a configuration change has been made the two LEDs associated with input power, labeled DC and PoE, on the Model 545DR’s front panel will flash in a distinctive pattern.

System – Call Light Support Choices are Off and On.
In STcontroller, the Call Light Support configuration function allows the call light support function to be enabled or disabled as desired. When the function is On, the call light support function is enabled. When the Call Light Support configuration is selected for Off the function is disabled. For most applications the call light support function should remain enabled. Only special circumstances would merit disabling the function.

System – PL Active Detection Choices are Off and On.
The Model 545DR’s current detection function will be active when both the local power source has been enabled and the PL Active Detection configuration has been selected for On. When these two parameters are selected a minimum current of 5 mA (nominal) must be drawn from pin 2 of the PL interface for the Model 545DR to recognize a “PL active” condition. When this minimum current condition is met the LED labeled ACTIVE on the unit’s front panel will light green, the PL Active status icon on the STcontroller’s menu page will show green, and the two Dante transmitter (output) audio paths will be active. Having the PL Active Detection function enabled is appropriate for most applications, helping to maintain the most stable audio performance. Only when sufficient current is drawn from pin 2 of the Model 545DR’s PL interface will audio from the PL channels be sent out the Dante transmitter (output) channels.

When the PL Active Detection configuration is selected to Off (disabled), no minimum current draw is required on pin 2 of the PL interface for the ACTIVE LED to be lit, the STcontroller graphics icon to display green, and the two Dante transmitter (output) channels to be active. However, only in special situations would it be appropriate for the PL Active Detection configuration be selected for Off. An example where Off would be appropriate would be the case where a Model 545DR is being used with a Telex® BTR-800 Wireless Intercom System. The BTR-800 is designed to directly interface with a party-line (PL) intercom circuit. This circuit would typically have DC power and one or two audio channels associated with it. (Each audio channel would typically have a terminating impedance of nominally 200 ohms.) The Model 545DR can provide such a PL circuit when the local power source is enabled. But a problem arises as the BTR-800 does not draw current from pin 2 of the connected PL intercom circuit. It doesn’t function in the same manner as would a typical PL intercom beltpack or user device. The BTR-800 doesn’t use power from the PL connection, instead using its internal power source for operation.

In this case, the Model 545DR’s party-line interface would not supply current, the ACTIVE LED would not light, the active icon in STcontroller would not turn green, and the two Dante transmitter (output) audio paths would not be enabled. Users of the BTR-800 would receive Model 545DR Dante receiver (input) audio but would not send audio out the two Dante transmitter (output) channels. Turning off the PL Active Detection function would resolve this issue. Even though no DC current would be supplied by the Model 545DR’s PL interface, the Dante transmitter (output) channels would be enabled and successful PL interface operation could take place.

When the Model 545DR has been set to not provide local power the PL Active Detection function works in a slightly different way. Only if a DC voltage of approximately 18 or greater is present on pin 2 of the PL interface will the Model 545DR recognize that a valid PL interconnection has been made. In this case, the ACTIVE LED on the front panel will light green, the virtual button in STcontroller will light green, and the Dante transmitter (output) audio channels will be active. When the PL Active Detection function is disabled, monitoring of DC voltage on pin 2 of the Model 545DR’s PL interface will not take place. In this situation, the ACTIVE LED on the Model 545DR’s front panel will always be lit, the virtual indicator in STcontroller would be lit, and the Dante transmitter (output) audio channels will be active. The practical application of this specific configuration has not been determined. But it’s ready should the need arise!

Operation

At this point, the Model 545DR should be ready for use. The party-line intercom and Ethernet connections should have been made. Depending on the application, an external source of 12 volts DC power may also have been made. (A 12 volts DC power source is not included with the Model 545DR. One can be purchased as an option.) The Dante receiver (input) and transmitter (output) channels should have been routed (subscribed) using the Dante Controller software application. Normal operation of the Model 545DR can now begin.

On the front panel, multiple LEDs provide an indication of the unit’s operating status. In addition, a pushbutton switch is provided to select the on/off status of the local power function as well as activating the auto null function. The STcontroller software application can be used to observe the status of some of the unit’s operating conditions. Virtual pushbutton switches associated with STcontroller also allow control of the on/off status of the local power source in addition to initiating the auto null function.

Initial Operation
The Model 545DR will begin its initial functioning a few seconds after its power source is connected.

As previously discussed, the power source can be provided by Power-over- Ethernet (PoE) or an external source of 12 volts DC. If both are connected the PoE source will power the unit. Should PoE subsequently no longer be available operation will continue using the external 12 volts DC source.

Upon Model 545DR power up many of the status and meter LEDs on the front and back panels will activate in test sequences. On the back panel, the LED associated  with the USB receptacle, labeled Firmware Update, will light green for a few seconds. Soon after that the Dante SYS and Dante SYNC LEDs will light red. After a few seconds they will start indicating the operating status of the Dante interface, turning green as valid conditions are established. The Ethernet LINK/ACT, also located on the back panel, will start to flash green in response to data flowing into and out of the Ethernet interface. On the front panel, the input power, auto null, party-line intercom circuit status, and level meter LEDs will light in a rapid test sequence. The Model 545DR will now begin normal operation. The exact manner in which the LINK/ACT, SYS, and SYNC LEDs (all located on the back panel below the etherCON RJ45 jack) light will depend on characteristics related to the connected Ethernet signal and the configuration of the unit’s Dante interface. Details will be covered in the next paragraph. On the front panel, the user is presented with one pushbutton switch, two input power status LEDs, two party-line intercom circuit status LEDs, two auto null LEDs, and four 5-segment LED level meters.
These resources are simple to understand and control, as will be described in the following paragraphs.

Ethernet and Dante Status LEDs
Three status LEDs are located below the etherCON RJ45 jack on the Model 545DR’s back panel.

The LINK/ACT LED will light green whenever an active connection to a 100 Mb/s Ethernet network has been established. It will flash in response to data activity. The SYS and SYNC LEDs display the operating status of the Dante interface and associated network. The SYS LED will light red upon Model 545DR power up to indicate that the Dante interface is not ready. After a short interval, it will light green to indicate that it is ready to pass data with another Dante device. The SYNC LED will light red when the Model 545DR is not synchronized with a Dante network. It will light solid green when the Model 545DR is synchronized with a Dante network and an external clock source (timing reference) is being received. It will slowly flash green when this specific Model 545DR unit is part of a Dante network and is serving as a Leader clock. (It’s important to note that typical applications will not have a Model 545DR unit serving as a Dante Leader clock.)

How to Identify a Specific Model 545DR
Both the Dante Controller and STcontroller software applications offer identify commands that can be used to help locate a specific Model 545DR. When an identify command is selected for a specific Model 545DR unit its meter LEDs will light in a unique pattern. In addition, the SYS and SYNC LEDs, located directly below the etherCON jack on the back panel, will slowly flash green. After a few seconds, the LED identification patterns will cease and normal Model 545DR level meter and Dante status LED operation will again take place.

Level Meters
The Model 545DR contains four 5-segment LED level meters. These meters are provided as a support aid during installation, configuration, operation, and troubleshooting. The meters represent the strength of the audio signals going to and coming from the two party-line intercom channels.

General
The meters are organized into two groups with each group representing one channel of audio being sent to the party-line circuit and one channel of audio being returned by the party-line circuit. The meters are calibrated to reflect the level in dB relative to the reference (nominal) level of the party-line intercom circuit. The Model 545DR’s nominal party-line level was selected to be –10 dBu, matching that utilized by typical 2-channel party-line intercom circuits.

Each level meter contains four green LEDs and one yellow LED. The four green LEDs indicate party-line intercom channel signal levels that are at or below –10 dBu. The top LED is yellow and indicates a signal that is 6 dB or greater than the –10 dBu nominal level. An audio signal that causes the yellow LED to light doesn’t necessarily indicate an excessive level condition, but it does provide a warning that reducing the signal level may be prudent. Typical operation with normal signal levels should find the meters lighting near their 0 point. Signal peaks may cause the yellow LEDs to flash. A yellow LED that lights fully during normal operation will indicate an excessive signal level configuration and/or a configuration problem with associated Dante enabled equipment.

As an example of how the meters function, let’s review the situation where the CHANNEL 1 TO meter has its bottom three LEDs (–18, –12, and –6) lit solid and its 0 LED just barely lighting. This would indicate that a signal with an approximate level of –10 dBu is being sent to channel 1 of the party-line intercom circuit. This would be a very appropriate signal level and should provide excellent operation. Also note that this –10 dBu signal being that is being sent to the party-line intercom channel would translate into a –20 dBFS digital audio signal present on the associated receiver (input) channel of the Dante interface.
This is due to Studio Technologies’ selecting –20 dBFS as the reference (nominal) level for Dante audio channels.

Non-Optimal Signal Levels
If one or more of the meters consistently display levels that are lower or higher than the 0 (reference) point it’s possible that a configuration issue exists. This would typically be related to incorrect settings on the equipment connected to the associated Dante receiver (input) and/or Dante transmitter (output) channels.
(It would be almost impossible for this situation to occur if two Model 545DR units are configured “pointto-point” as no Dante digital audio level adjustment is provided.) With a digital matrix intercom system this problem could be due to an incorrect configuration having been made to a specific channel or port. For example, the RTS/Telex/Bosch ADAM system has a published nominal audio level of +8 dBu, but it’s not clear how this translates into a digital audio level on an associated Dante or OMNEO channel. (OMNEO is the term that RTS uses to refer to their Dante ports.) Using its AZedit configuration software it’s possible to set the nominal level of intercom key panels or ports to something different than +8 dBu. The best solution in this case might be to adjust the associated OMNEO (Dante-compatible) port such that it results in nominal audio levels of –20 dBFS on the associated Dante transmitter (output) and receiver (input) channels. Providing compatible digital audio reference levels would lead to the best performance of the Model 545DR and associated party-line user devices.

Audio Levels and Party-Line Termination
The two FROM meters display the audio signal levels coming from the two channels associated with the Model 545DR’s party-line intercom circuit. These analog signals are converted to digital and then output on Dante transmitter (output) channels. For a party-line intercom circuit to function correctly, the impedance (resistance to AC signals such as audio) must be approximately 200 ohms. Typically, to achieve this depends on a single piece of equipment providing one audio termination per intercom channel. This termination, 200 ohms nominally, is almost always made at the intercom power supply source. (An intercom power supply unit typically provides both DC power and one or two intercom termination networks.)

An issue may arise if the audio signals coming from the connected party-line intercom circuit or user devices aren’t at a sufficient level such that normal meter display levels can be reached. It’s possible that another device, such as a second intercom power supply on the same party-line intercom circuit, can cause a “double-termination” condition. This would result in a party-line intercom channel impedance of approximately 100 ohms (two sources, each 200 ohms, connected in parallel) which would cause major issues. The most evident problem would be that the intercom channel’s nominal audio levels would attenuate (drop) by about 6 dB. In addition, auto null circuits, such as provided by the Model 545DR, will not be able to obtain good separation (nulling) performance.
Removing the unwanted second termination (the second impedance of 200 ohms) is the only effective means of eliminating the problems.

In most cases, a double-termination issue will be simple to solve. It’s easily possible for the Model 545DR’s local power source, which provides both DC power and 200 ohms termination networks for the two channels, to be accidentally enabled when the Model 545DR is connected to an externally powered and terminated party-line circuit. This would be incorrect, leading to the “double-termination” condition. Turning off the Model 545DR’s local power source by pressing and holding the auto null button or using the STcontroller software application is all that is required.
Some intercom power supply units allow selection of the termination impedance to be 200 or 400 ohms.

This capability is often incorporated into a 3-position switch that also allows no termination impedance to be application. Ensure that the selected switch setting, as well as the settings and deployment of other connected equipment, results in an intercom circuit impedance of 200 nominal for each of the two channels.

Power Status LEDs
Two green LEDs are located on the left side of the front panel and are associated with operating power.
The PoE LED indicator will light whenever an Ethernet connection with Power- over-Ethernet (PoE) capability is connected. The DC power LED will light whenever an external DC voltage has been applied. The acceptable range is 10 to 18 volts DC. If both power sources are present both LEDs will light, however only the PoE source will be providing the Model 545DR’s operating power.

Party-Line Operating Mode Selection

As discussed previously, the Model 545DR provides two party-line circuit operating modes. One mode is used when the Model 545DR is required to create a 2-channel party-line intercom circuit, providing 29 volts DC and two 200 ohms termination impedance networks. In this mode, user devices such as beltpacks can be directly supported. The LOCAL POWER status LED will light green when this mode is selected. A virtual (software-based-graphics) button that’s part of the STcontroller application will show the text On to indicate that local power has been enabled.

The second mode allows the Model 545DR to be connected to a 2-channel party- line intercom circuit that provides both DC power and two channels of 200 ohms terminating impedance. In this mode, the unit will perform in the same manner as a user device and the LOCAL POWER status LED will not be lit. In this mode, the text Off will be shown in the STcontoller’s virtual pushbutton switch.

To change to the desired operating mode is simple, only requiring the AUTO NULL pushbutton switch to be pressed and held for a minimum of two seconds.

This will cause the Model 545DR’s operating mode to change (“toggle”) from one mode to the other. As the mode changes, the LOCAL POWER status LED and STcontroller application will display accordingly.

Once the mode has changed the pushbutton switch can then be released. The operating mode can also be selected using the virtual pushbutton switch in the STcontroller software application. The selected operating mode will be stored in non-volatile memory, ensuring that it will restore to that value after a power-down/power-up cycle.

Local Power Mode Operation
When the Model 545DR’s local power mode is enabled, the unit will provide DC power and two 200 ohms termination impedances to create a 2-channel party-line intercom circuit. The party-line interface supplies 29 volts DC on pin 2 of the 3-pin XLR connectors with a maximum current draw of 240 mA available. This current is sufficient to power various intercom user devices such as small user stations and beltpacks. A common broadcast application may use RTS BP-325 beltpacks. Select the connected devices so that their total maximum current doesn’t exceed 240 mA. That’s not always the easiest figure to calculate but a web search will generally find specifications for all commonly used devices. For example, a search finds that the original (very, very early) version of the BP-325 consumes a maximum of 85 mA of current.
According to this figure, one or two of these units can be connected to a Model 545DR. All newer versions of the BP-325 use surface-mount component technology and have a maximum current draw of 65 mA. Up to three of these “modern” BP-325 units can easily be supported.

When local power has been enabled, the ACTIVE status LED will light green when a minimal amount of current is flowing from the Model 545DR to the connected user device or devices. This will also cause the virtual LED named PL Active in the STcontroller application to light green. This current, 5 mA nominal, provides a party-line power source-active signal to the Model 545DR’s firmware, indicating that normal operation is taking place. The firmware, in turn, will cause the ACTIVE status LED to light, the STcontroller application to light its virtual LED, and the two Dante transmitter (output) audio channels to be in their active (unmuted) state. (By muting the Dante transmitter (output) channels when the intercom circuit is not active, unwanted audio signals will be prevented from passing to the outside world when no party-line devices are connected.)

Note that a setting in the STcontroller application can disable the requirement that a current draw of 5 mA (nominal) or greater on pin 2 of the party-line XLR connectors is required for the ACTIVE status LED to light, the virtual LED in the STcontroller application to light green, and the two transmitter (output) audio paths to be active. This function is called PL Active Detection and disabling it can be appropriate for special applications. Refer to the Model 545DR Configuration section for details regarding this function and how it may be utilized.

The Model 545DR’s party-line intercom power supply circuit operates under firmware control. This allows detection of fault conditions and protection of the unit’s circuitry. Upon initially enabling the Model 545DR’s party-line intercom power supply no monitoring of the intercom power output takes place for three seconds. This allows the Model 545DR’s intercom power supply circuitry and the connected intercom user device or devices to stabilize. The LOCAL POWER status LED will be lit solid and the virtual pushbutton switch in the STcontroller application will show the text On. The ACTIVE status LED, which responds to the status of the DC voltage on pin 2 of the party-line interface’s 3-pin XLR connectors, will light to indicate that the output is active. The PL Active virtual LED in STcontroller will light green. After this initial delay, monitoring becomes active. A fault condition is detected if the voltage on pin 2 falls below 24 for a continuous 1-second interval. The firmware responds to this condition by momentarily turning off the DC power source to pin 2. It will also, as a warning, flash the ACTIVE status LED and flash the virtual LED in STcontroller. After a 5-second “cool-down” interval the DC output will return to the same condition as upon initial power up; power is again applied to pin 2, the ACTIVE status LED will light, the virtual PL Active LED will light green, and monitoring won’t begin for another three seconds. A full short-circuit condition applied to the Model 545DR’s party- line circuit will result in a continuous cycle of four seconds on (three seconds for startup and one second for detection) and then five seconds off.

External Party-Line Circuit Operation
When the LOCAL POWER status LED on the front panel is not lit, and the virtual pushbutton switch in STcontroller is labeled Off, the Model 545DR’s party-line interface does not provide DC power on pin 2 of the XLRs nor provides 200 ohms terminating impedances on pins 2 and 3. In this mode, the Model 545DR is intended to be connected to an externally powered party-line circuit. This party-line circuit must provide the DC power and termination impedances required to create the party-line intercom circuit. In this mode, the Model 545DR simply serves in the same fashion as that of another connected user device. (In effect, the Model 545DR would have the technical characteristics of a non-powered user device.) When connected to a powered party-line circuit the Model 545DR’s ACTIVE status LED will light when approximately 18 volts DC or greater is present on pin 2 of the XLR connectors. In addition, the STcontroller’s PL Active virtual LED will light green. When this condition is detected, the Dante transmitter (output) channels are placed in their active (non-muted) state. Otherwise, they are off (muted) to maintain stable Model 545DR performance.

As previously described, a setting in the STcotnroller application can disable the requirement that 18 volts DC or greater be present on pin 2 of the party- line XLR connectors for the ACTIVE status LED to light, the PL Active virtual LED to light green, and the transmitter (output) audio paths to be active. This function is called the PL Active Detection function and disabling it can be appropriate for special applications. Refer to the Model 545DR Configuration section for details regarding this function and how it may be utilized.

Auto Null
The Model 545DR contains circuitry to automatically null the hybrid networks associated with the two party-line interface channels. This procedure separates the audio signals as they are sent to and received from the two channels associated with the party-line intercom circuit. A pushbutton switch, located on the front panel, is provided to activate the two auto null functions, one for each channel. A virtual (“soft”) button in the STcontroller software application also allows activation of the auto null functions. Two status LEDs, located on the unit’s front panel, and two virtual (software- graphics-based) LEDs provided in STcontroller provide an indication of the operation of the auto null circuits.
To initiate auto null first requires that the ACTIVE status LED be lit. When the operating mode is set for local power the ACTIVE status LED will light when the required minimum amount of current is flowing from the internal power supply. Alternately, when the LOCAL POWER LED is not lit the ACTIVE status LED must be lit, indicating that sufficient DC voltage is present on pin 2 of the connected party-line circuit.
Once the ACTIVE status LED is lit, initiating the auto null function only requires pressing and releasing (“tapping”) the front-panel auto null button. Alternately, the virtual button in the STcontroller application can be used to initiate auto null. The auto null process is performed on both channels at essentially the same time and take approximately 15 seconds to complete.

Two LEDs on the unit’s front panel provide a visual indication of the auto null process, flashing orange when the auto null process for its respective channel is active. Virtual LEDs in the STcontroller application provide the same function. They are labeled Ch 1 (Pin 2) and Ch 2 (Pin 3) to directly indicate which auto null function is active.
If the auto null button is pressed, either on the front panel or in STcontroller, when the ACTIVE status LED is not lit the auto null process will not start. The auto null LEDs will quickly flash orange four times to indicate this condition.
Normally, the nulling process is performed at the time of initial Model 545DR configuration but there’s no reason why it can’t be initiated any time one desires.

The only time that auto null must be performed is if conditions have changed with the party-line user devices and wiring connected to a Model 545DR’s party-line connectors. Even a small change to a party-line intercom circuit, such as adding or removing a section of cable, may be enough to require that the auto null process be performed.

An auto null sequence begins with the muting of the Dante receiver (input) and Dante transmitter (output) audio signal paths. This is followed by a short period of a 24 kHz sine wave signal that is sent to both channels of the party-line intercom interface. This will turn off microphones on those connected user devices that are compatible with the RTS TW-series “mic kill” protocol. The actual auto nulling process is performed next. A series of tones will be sent to both channels of the party-line interface. Other Model 545DR circuitry, under firmware control, will rapidly perform adjustments to achieve the best null possible.
After the adjustments have been made the results are stored in the Model 545DR’s non-volatile memory.
Once the process is complete, the Dante receiver (input) and Dante transmitter (output) audio paths are again activated.

If possible, prior to performing an auto null it’s polite to warn all personnel who are actively using the connected party-line intercom devices. The tones sent to the party-line circuit during the nulling process are not excessively loud or obnoxious, but most users might want to remove their headsets during the process.
In addition to warning users, it might be a good time to ask them to mute any active microphones. While the automatic “mic kill” signal will be compatible with many user devices it may not apply to all. Muting microphones is significant, as obtaining a “deep” nul requires that no extraneous signals be present on the intercom circuit.

Call Light Support
The Model 545DR provides a call light support function, allowing high- frequency signals associated with the call light functions on Model 5454DR- connected user devices to work together. The function also allows a Model 545DR to interconnect with a Model 45DC or Model 545DC Intercom Interface unit and support inter-unit call light activity. No operator action is required for the call light support function to perform its task.

The call light support function is actually quite interesting. Implemented in software, it allows a highfrequency tone received on one of the Dante receiver (input) channels to be detected and then sent out (“repeated”) as a precise 20 kHz analog sine wave signal on the associated party-line intercom channel.

A high-frequency signal received on either of the party-line channels will result in the Model 545DR’s circuitry sending a 20 kHz sine wave tone out its associated Dante transmitter (output) channel. Digitally implemented low-pass (LP) filters prevent a highfrequency tone on one “side” from directly passing th call signal through to the other side; the unit’s circuitry detects the high frequency signals, filters them out, and re-sends them as precise tones. This ensures that the call signals are presented to both sides (analog party- line and Dante) at an optimal level, frequency, and signal type (waveform).

A selection in the STcontroller application allows disabling of call light support. Technically, this instructs the unit’s application firmware (embedded software) to not generate a 20 kHz tone when a highfrequency “call” tone is received.

The filtering of the high-frequency signal (using low-pass filters) will always stay active. Disabling call light support would be appropriate only in very specialized applications.

USB Interface
A USB type A receptacle and an associated status LED, labeled Firmware Update, are located on the Model 545DR’s back panel. This USB host interface is used only for updating the unit’s application firmware; no audio data of any kind will pass through it. For details please refer to the Technical Notes section.

Technical Notes

IP Address Assignment
By default, the Model 545DR’s Dante-associated Ethernet interface will attempt to automatically obtain an IP address and associated settings using DHCP (Dynamic Host Configuration Protocol). If a DHCP server is not detected an IP address will automatically be assigned using the link-local protocol. This protocol is known in the Microsoft® world as Automatic Private IP Addressing (APIPA). It is also sometimes referred to as auto-IP (PIPPA). Link-local will randomly assign a unique IP address in the IPv4 range of 169.254.0.1 to 169.254.255.254. In this way, multiple Dante-enabled devices can be connected together and automatically function, whether or not a DHCP server is active on the LAN. Even two Dante-enabled devices that are directly interconnected using an RJ45 patch cord will, in most cases, correctly acquire IP addresses and be able to communicate with each other.

An exception does arise when trying to directly interconnect two Dante-enabled devices that use Ultimo integrated circuits to implement Dante. The Model 545DR uses an UltimoX2 “chip” and, as such, a direct one-to-one interconnection between it and another Ultimo-based product would typically not be supported. An Ethernet switch linking these units would be required to successfully interconnect the two Ultimo-based devices. The technical reason tha a switch is required relates to the need for a slight latency (delay) in the data flow; an Ethernet switch will provide this. This wouldn’t typically prove to be an issue as the Model 545DR uses Power-overEthernet (PoE) to provide its operating power. As such, in most cases a PoE-enabled Ethernet switch would be utilized to support Model 545DR units.

Using the Dante Controller software application, the Model 545DR’s IP address and related network parameters can be set for a manual (fixed or static) configuration. While this is a more involved process than simply letting DHCP or link-local “do their thing,” if fixed addressing is necessary then this capability is available. But in this case, it’s highly recommended that every unit be physically marked, e.g., directly using a permanent marker or “console tape,” with its specific static IP address. If knowledge of a Model 545DR’s IP address has been misplaced there is no reset button or other method to easily restore the unit to a default IP setting.

In the unfortunate event that a device’s IP address is “lost,” the Address Resolution Protocol (ARP) networking command can be used to “probe” devices on a network for this information. For example, in Windows OS the arp –a command can be used to display a list of LAN information that includes MAC addresses and corresponding IP addresses. The simplest means of identifying an unknown IP address is to create a “mini” LAN with a small PoE-enabled Ethernet switch connecting a personal computer to the Model 545DR. Then by using the appropriate ARP command the required “clues” can be obtained.

Optimizing Network Performance
For best Dante audio-over-Ethernet performance a network that supports VoIP QoS capability is recommended. In applications that utilize multicast Ethernet traffic enabling IGMP snooping can be valuable. (In this case, ensure that support for PTP timing messages is still available.) These protocols can be implemented on virtually all contemporary managed Ethernet switches. There are even specialized switches that are optimized for entertainment-associated applications. Refer to the Audinate website (audinate. com) for details on optimizing networks for Dante applications.

Application Firmware Version Display
A selection in the STcontroller software application allows the Model 545DR’s application firmware version to be identified. This can be useful when working with factory personnel on application support and troubleshooting. To identify the firmware version, begin by connecting the Model 545DR unit to the network (via Ethernet with PoE) and wait until the unit starts to function. Then, after starting STcontroller, review the list of identified devices and select the specific Model 545DR for which you want to determine its application firmware version. Then select Version and Information under the Device tab. A page will then display that will provide lots of useful information. This includes the application firmware version and well as details on the Dante interface firmware.

Application Firmware Update Procedure
It’s possible that updated versions of the application firmware (embedded software) that is utilized by the Model 545DR’s microcontroller (MCU) integrated circuit will be released to add features or correct issues. Refer to the Studio Technologies’ website for the latest application firmware file. The unit has the ability to load a revised file into its MCU’s nonvolatile memory by way of a USB interface. The Model 545DR implements a USB host function that directly supports connection of a USB flash drive. The Model 545DR’s MCU updates its application firmware using a file named M545DRvXrXX.stm where the Xs are decimal digits that represent the actual firmware version number.

The update process begins by preparing a USB flash drive. The flash drive doesn’t have to be empty (blank) but must be in the personal-computer-standard FAT32 format. The USB interface in the Model 545DR is compatible with USB 2.0-, USB 3.0-, and USB 3.1-compliant flash drives. Save the new application firmware file in the root directory of the flash drive with a name of M545DRvXrXX.stm where the XrXX is the actual version number. Studio Technologies will supply the application firmware file inside of a .zip archive file. The name of the zip file will reflect the application file’s version number and will contain two files. One file will be the actual application file and the other a readme (.txt) text file. It’s recommended that the readme (.txt) file be reviewed as it will contain details about the associated application firmware.
The application firmware file inside of the zip file will adhere to the required naming convention.
Once the USB flash drive is inserted into the USB host interface, by way of a USB type A receptacle that is located on the Model 545DR’s back panel, the unit must be powered off and again powered on. At this point, the file from the USB flash drive will automatically load. The precise steps required will be highlighted in the next paragraphs.

To install the application firmware file, follow these steps:

1. Disconnect power from the Model 545DR. This may entail either removing the PoE Ethernet connection that is made to the RJ45 jack on the back panel. Alternately, it may involve removing a source of 12 volts DC that is connected to the 4-pin XLR connector, also location on the back panel.
   2 Insert the prepared USB flash drive into the USB receptacle on the back panel of the unit.

2. Apply power to the Model 545DR either by connecting a PoE Ethernet signal or a source of 12 volts DC.

3. After a few seconds the Model 545DR will run a “boot loader” program that will automatically load the new application firmware file (M545DRvXrXX. stm). This loading process will take only a few seconds. During this time period the green LED that’s located adjacent to the USB receptacle will flash slowly. Once the entire loading process is over, taking approximately 10 seconds, the Model 545DR will restart using the newly loaded application firmware.

4. At this time, the Model 545DR is functioning with the newly loaded application firmware and the USB flash drive can be removed. But to be conservative, remove the PoE Ethernet connection or 12 volts DC power source first and then remove the USB flash drive. Re-connect the PoE Ethernet connection or the 12 volts DC power source to restart the unit.

5. Using STcontroller, confirm that the desired application firmware version has been correctly loaded.

Note that upon power being applied to the Model 545DR if a connected USB flash drive doesn’t have the correct file (M545DRvXrXX.stm) in its root folder no harm will occur. Upon power up the green LED, adjacent to the USB receptacle on the back panel, will flash on and off rapidly for a few seconds to indicate this condition and then normal operation using the unit’s existing application firmware will begin.

Ultimo Firmware Update
As previously discussed, the Model 545DR implements its Dante connectivity using the UltimoX2 integrated circuit from Audinate. The STcontroller or Dante Controller software applications can be used to determine the version of the firmware (embedded software) that resides in this integrated circuit.
The firmware (embedded software) residing in the UltimoX2 can be updated by way of the Model 545DR’s Ethernet port. Performing the update process is easily accomplished using an automated method called Dante Updater that’s included as part of the Dante Controller application. This application is available, free of charge, from the Audinate website (audinate.com). The latest Model 545DR firmware file, with a name in the form of M545DRvXrXrX.dnt, is available on the Studio Technologies’ website as well as being part of Audinate’s product library database. The latter allows the Dante Updater software application that is included with Dante Controller to automatically query and, if required, update the Model 545DR’s Dante interface.

Restoring Factory Defaults
A command in the STcontroller software application allows the Model 545DR’s defaults to be reset to the factory values. From STcontroller select the Model 545DR for which you want to restore its defaults.
Select the Device tab and then the Factory Defaults selection. Then click on the OK box. Refer to Appendix A for a list of the Model 545DR’s factory defaults.

Specifications

Power Sources:
Power-over-Ethernet (PoE): class 3 (mid power) per IEEE® 802.3af
External: 10 to 18 volts DC, 1.0 A max at 12 volts DC

Network Audio Technology:
Type: Dante audio-over-Ethernet
AES67-2018 Support: yes, selectable on/off
Dante Domain Manager (DDM) Support: yes
Bit Depth: up to 24
Sample Rate: 48 kHz
Dante Transmitter (Output) Channels: 2
Dante Receiver (Input) Channels: 2
Dante Audio Flows: 4; 2 transmitter, 2 receiver
Analog to Digital Equivalence: a –10 dBu analog signal on a party-line interface channel results in a Dante digital output level of –20 dBFS and vice-versa

Network Interface:
Type: 100BASE-TX, Fast Ethernet per IEEE 802.3u
(10BASE-T and 1000BASE-T (GigE) not supported)
Power-over-Ethernet (PoE): Per IEEE 802.3af
Data Rate: 100 Mb/s (10 Mb/s and 1000 Mb/s not supported)

General Audio:
Frequency Response (PL to Dante): –0.3 dB @ 100 Hz (–4.8 dB @ 20 Hz), –2 dB @ 8 kHz (–2.6 dB @ 10 kHz)
Frequency Response (Dante to PL): –3.3 dB @ 100 Hz (–19 dB @ 20 Hz), –3.9 dB @ 8 kHz (–5.8 dB @ 10 kHz)
Distortion (THD+N): <0.15%, measured at 1 kHz, Dante input to PL interface pin 2 (0.01% pin 3)
Signal-to-Noise Ratio: >65 dB, A-weighted, measured at 1 kHz, Dante input to PL interface pin 2 (73 dB, PL interface pin 3)
Party-Line (PL) Intercom Interface:
Type: 2-channel analog PL, unbalanced (XLR pin 1 common; XLR pin 2 DC with channel 1 audio; XLR pin 3 channel 2 audio)
Compatibility: 2-channel PL intercom systems such as those offered by RTS®
Po w er Source: 29 volts DC, 240 mA maximum, on
XLR pin 2
Impedance – Local PL Power Not Enabled: >10 k ohms
Impedance – Local PL Power Enabled: 200 ohms
Analog Audio Level: –10 dBu, nominal, +3 dBu maximum, PL interface XLR pin 2 (+7 dBu maximum, PL interface XLR pin 3)
Call Light Signal Support: 20 kHz, ±800 Hz
Mic Kill Signal Support: 24 kHz, ±1%
Party-Line (PL) Hybrids: 2
Topology: 3-section analog circuitry compensates for resistive, inductive, and capacitive loads
Nulling Method: automatic upon user initiation, processor implements digital control of analog circuitry; settings stored in non-volatile memory
Nulling Line Impedance Range: 120 to 350 ohms
Nulling Cable Length   Range: 0 to 3500 feet
Trans-Hybrid Loss: >50 dB, typical at 800 Hz, PL interface XLR pin 2 (>55 dB, PL interface XLR pin 3)
Meters: 4
Function: displays level of audio input and output channels
Type: 5-segment LED, modified VU ballistics Connectors:
Party-Line (PL) Intercom: 3-pin male and female XLR
Ethernet: Neutrik etherCON RJ45 jack
External DC: 4-pin male XLR
USB: type A receptacle (used only for updating application firmware)
Configuration: requires Studio Technologies’ STcontroller software application
Software Updating: USB flash drive used for updating application firmware; Dante Updater application used for updating Dante interface firmware Environmental:
Operating Temperature: 0 to 50 degrees C (32 to 122 degrees F)
Storage Temperature: –40 to 70 degrees C (–40 to 158 degrees F)
Humidity: 0 to 95%, non-condensing
Altitude: not characterized
Dimensions – Overall:
8.70 inches wide (22.1 cm)
1.72 inches high (4.4 cm)
8.30 inches deep (21.1 cm)
Weight: 1.7 pounds (0.77 kg); rack-mounting installation kits add approximately 0.2 pounds (0.09 kg)
Deployment: intended for tabletop applications.
Four optional mounting kits are also available:
RMBK-10 allows one unit to be mounted in a panel cutout or on a flat surface
RMBK-11 allows one unit to be mounted in the leftor right-side of one space (1U) of a standard 19-inch rack
RMBK-12 allows two units to be mounted in one space (1U) of a standard 19-inch rack
RMBK-13 allows one unit to be mounted in the center of one space (1U) of a standard 19-inch rack
DC Power Supply Option: Studio Technologies’ PS-DC-02 (100-240 V, 50/60 Hz, input; 12 volts DC, 1.5 A, output), purchased separately

Specifications and information contained in this User Guide subject to change without notice.

Appendix A–STcontroller Default Configuration Values

System – Call Light Support: On
System – PL Active Detection: On

Appendix B–Graphical Description of the Installation Kit for Panel Cutout or Surface-Mounting Use (Order Code: RMBK-10)
This installation kit is used for mounting one Model 545DR unit into a panel cutout or flat surface.

Appendix C–Graphical Description of Left- or Right-Side Rack-Mount Installation Kit for One “1/2-Rack” Unit (Order Code: RMBK-11)
This installation kit is used for mounting one Model 545DR unit into one space (1U) of a 19-inch equipment rack. Unit will be located on the left- or right- side of the 1U opening.

Appendix D–Graphical Description of Rack-Mount Installation Kit for Two “1/2-Rack” Units (Order Code: RMBK-12)
This installation kit can be used to mount two Model 545DR units or one Model 545DR unit and another product that is compatible with the RMBK-12 (such as the Studio Technologies’ Model 5421 Dante Intercom
Audio Engine) into one space (1U) of a 19-inch equipment rack.

Appendix E–Graphical Description of Center Rack-Mount Installation Kit for One “1/2-Rack” Unit (Order Code: RMBK-13)
This installation kit is used for mounting one Model 545DR unit into one space (1U) of a 19-inch equipment rack. Unit will be located in the center of the 1U opening.

References

• Audinate - Pioneering the future of AV
• Home - Studio Technologies, Inc.

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