The Model 543D IFB Interface provides broadcast-standard powered and line-level (non-powered) analog IFB outputs from audio signals that are supplied by way of Dante® audio-over-Ethernet media networking technology. IFB, also known as "interruptible foldback" or talent cueing, is a method commonly used by broadcast on-air talent and related personnel to receive one-way (listen-only) audio signals associated with live-event broadcasts. Especially important in sports and entertainment events, IFB plays a crucial role in virtually all broadcast applications that require people to stay "in the know." Dante has found wide acceptance as an audio "backbone" due to its ease of use, high performance, strong interoperability, and wide adoption by a large number of equipment manufacturers. The Model 543D is a unique product that helps to extend Dante’s capabilities into the important but specialized world of broadcast and production IFB.
Dante audio-over-Ethernet technology is used to transport four audio channels from their source to the Model 543D and then on to the two, 2-channel IFB outputs. Each of the Model 543D's powered IFB outputs supplies DC voltage and two audio channels to groups of listen-only user devices. Two analog line-level IFB outputs are also provided for general-purpose use. The Model 543D is compatible with the latest broadcast and audio equipment that uses Dante technology. An Ethernet connection is all that’s required to make the Model 543D part of a sophisticated, networked audio system.
A Model 543D can utilize up to four digital audio input channels provided by Dante-enabled devices such as matrix intercom systems, DSP processors, broadcast routers, and audio consoles. The unit's powered IFB outputs allow direct connection with listen-only user beltpacks such as the Studio Technologies' Model 32A, Model 33A, or Model 34. The powered IFB outputs also support connection of listen-only devices from manufacturers such as RTS® and Clear-Com®. Two LED indicators serve as status displays for the 28 volts DC that is an integral part of each powered IFB output. The two line-level IFB outputs are provided for connection with a variety of devices that have balanced or unbalanced analog inputs.
Four audio level meters, located on the unit's front panel, provide confirmation of system performance during setup and operation. Careful attention to circuit design and component selection ensures that excellent audio quality is maintained. The Model 543D's operating power can be provided either by a power-over-Ethernet (PoE) connection or an external source of 12 volts DC. Two front-panel LEDs display the status of the PoE and/or DC sources. Standard connectors are used for the powered and line-level IFB outputs, Ethernet, and DC power interconnections. The Model 543D'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 installation kits, one or two Model 543D units can be mounted in a single space (1U) of a standard 19-inch rack enclosure.
In addition to the front-panel LEDs, the STcontroller software application allows DC status monitoring for the two powered IFB outputs. 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.
Digital audio data is sent to the Model 543D using the Dante audio-over-Ethernet media networking technology. Audio signals with a sample rate of 48 kHz and a bit depth of 16, 24, or 32 are supported. Using the Dante Controller application, up to four Dante transmitter (output) channels on associated equipment can be assigned to the unit’s Dante receiver (input) channels. This makes it simple to select the way in which a Model 543D fits into a specific application.
The Model 543D was designed to add broadcast-standard 2-channel IFB functionality to Dante-enabled broadcast and related applications. Combining the networked audio capability of Dante with traditional analog powered ("wet") and non-powered ("dry" or line-level) IFB outputs allows traditional, proven cueing methods to be maintained.
The Model 543D can be used in applications where IFB (talent cueing) channels are created in matrix intercom systems and become part of a Dante audio-over-Ethernet network deployment. Output ports on matrix intercom systems that directly support Dante, such as the RTS ODIN® or ADAM® with OMNEO™, can be routed to the Model 543D's Dante receiver (input) channels. The Model 543D's circuitry will then convert these signals into analog powered and line-level (non-powered) IFB audio outputs. In this way, adding IFB support for RTS + OMNEO infrastructures is a simple task. Other matrix intercom and broadcast router systems also directly support Dante.
The Model 543D can also be used with matrix intercom systems that don't directly support Dante. An external analog-to-Dante interface can be used to convert analog intercom output ports to Dante channels. For example, the Studio Technologies' Model 544D or Model 5412 audio interfaces do an excellent job of converting line-level analog signals to Dante digital audio channels. Once in the Dante digital domain, these audio channels can be transported over standard Ethernet networks and then interconnected with the Model 543D's audio input channels.
In applications where on-air talent uses headsets with two earphones (stereo or "dual muff"), two unique audio channels are typically part of the provided IFB signal source. Generally, one channel is configured in a matrix intercom system as "interrupt" while the other channel is configured as "program" or "program only." (In U.S. applications the former signal is typically assigned to the left ear and the latter signal to the right ear.) An alternate term often used for the "interrupt" channel is "program-with-interrupt." This is probably a more descriptive as the function is actually a program source that gets interrupted with talk audio. The source of interrupt audio is typically a producer or director who provides real-time information to the on-air talent. The "program" channel is typically a continuous source of program audio.
In other applications, talent will use a single-ear headset, earbud, or in-ear monitor, keeping the other ear accessible to ambient audio. This is frequently done in electronic news gathering (ENG) or sports-broadcast applications where live interviews take place. A program-with-interrupt audio signal is normally provided; no program-only audio source is utilized.
Powered IFB Outputs
The Model 543D provides two, 2-channel powered IFB outputs that are designed to directly support connection of listen-only user devices. Each powered IFB output provides both DC voltage and two channels of unbalanced analog audio. Two, 3-pin male XLR connectors, located on the Model 543D's back panel, are used to interface the powered IFB outputs with the listen-only user devices. Following broadcast-industry conventions, pin 1 is the common connection, pin 2 has DC power with channel 1 audio superimposed on it, and pin 3 has channel 2 audio. The nominal audio levels are –10 dBu. Each power source supplies 28 volts DC with a maximum current of 120 milliamperes. The DC power sources are monitored for over-current and short-circuit conditions. Under firmware (embedded software) control the DC power sources will automatically cycle off and on to help prevent damage to the circuitry and connected equipment.
Line-Level IFB Outputs
The Model 543D provides two analog line-level IFB output channels. The audio sources for these two outputs are the same as used for channels 1 and 2 of powered IFB output 2. The line-level IFB outputs are intended to allow interconnection with externally powered listen-only user devices, inputs on wireless IFB systems, or analog inputs on consoles or related audio devices. The nominal level of the line-level IFB outputs is +4 dBu. The outputs are electronically balanced, capacitor-coupled and ESD (static) protected. They should be compatible with virtually all balanced and unbalanced line-level analog inputs that have an impedance of 2 k ohms or greater.
Reliability and Pro Audio Quality
The Model 543D is a fully professional product that offers the audio quality, features, and reliability required by 24-hour, on-air, and commercial applications. The unit's audio circuitry was designed in the spirit of professional audio equipment rather than that found in typical IFB or talent cueing gear. High performance components are used throughout, providing low-distortion, low-noise, and high headroom. The powered IFB outputs offer a unique level of performance, able to deliver reliable power and excellent audio quality in a variety of challenging applications.
The Model 543D provides four 5-segment LED meters. The meters, located on the unit’s front panel, display the level of the audio signals associated with the two, 2-channel IFB outputs. At the time of installation and setup the meters can be invaluable in helping to confirm correct operation. During normal operation the meters offer a real-time confirmation of the unit's incoming audio signal levels, helping to ensure that optimal audio quality is maintained.
Two LED indicators, located on the Model 543D's front panel, offer a status indication of the DC power sources that are part of the powered IFB outputs. Two other LEDs offer a direct indication of what source or sources of power are connected to the Model 543D. In addition, the STcontroller software application provides a real-time "virtual" status display of the DC power sources that are associated with the powered IFB outputs.
Ethernet Data, PoE, and DC Power Source
The Model 543D 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 CAT5-compatible plug allows a ruggedized and locking interconnection method for harsh or high-reliability environments. Three LEDs on the unit’s back panel display the status of the network connection and Dante interface.
The Model 543D'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 543D's PoE interface reports to the power sourcing equipment (PSE) that it is a class 3 (mid power) device. Alternately, the unit can be powered using an external source of 12 volts DC. For redundancy, both power sources can be connected simultaneously. Two LEDs on the unit’s front panel provide a real-time indication of the connected power sources.
The Model 543D uses standard connectors to allow fast and convenient interconnections. A twisted-pair Ethernet signal is connected using a Neutrik etherCON RJ45 jack. If Power-over-Ethernet (PoE) is available operation will commence immediately. An external source of 12 volts DC can also be connected by way of a 4-pin female XLR connector. Powered IFB and line-level IFB output connections are made using 3-pin male XLR connectors. The Model 543D 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. Installation kits are available, as an option, allowing one or two Model 543D units to be mounted in one space (1U) of a standard 19-inch rack enclosure. Mounting in a panel cutout or to a flat surface is also possible.
Future Capabilities and Firmware Updating
The Model 543D was designed so that its capabilities and performance can easily be enhanced in the future. A USB receptacle, located on the unit's back panel, allows the application firmware (embedded software) to be updated using a USB flash drive. The Model 543D's Dante interface uses the UltimoX4™ 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.