A complete Euphonix digital audio system is lightweight, making it ideal for trucks and remote applications. Shown here is a System 5-B digital audio mixing console on a Mobile Television Group HDX remote truck.
With the increasing complexity of broadcast production, the demands placed upon audio operators and technical engineers have similarly increased. An audio operator may be required to simultaneously check the main audio sources, patch isolated router feeds for tape and mix down pre-production spots.
Similarly, the technical engineers must configure the router control panels as sources become available, and this must happen with a minimum of interruption to tape production. Last-minute changes are inevitable, and in situations where audio router space is limited, entire set-ups may require modification.
To address this, audio installations for trucks and broadcast facilities generally require the specification of two audio systems: the digital audio mixer's router and the panel-controlled router/switcher system. The two systems are nearly identical and differ only in the manner in which they are controlled.
However, despite their similarities, integrators frequently find themselves purchasing separate audio frames from multiple vendors as single systems seldom provide this dual functionality. Furthermore, duplication of sources and interconnection between the two requires large numbers of source distribution amplifiers and additional router I/O. This raises the system's cost, increases complexity and limits the capabilities of both.
The SH612 MADI router
Having identified the inefficiencies, Euphonix worked toward a solution. Its digital audio mixing systems can now fully integrate with most router control systems using the ES-Control protocol — supported by models from PESA, NVISION, Pro-Bel, Sony, Grass Valley and Utah Scientific. The result is simpler, more efficient audio systems.
To achieve maximum flexibility in signal routing, Euphonix consoles use the SH612 MADI router. It has a 2RU form factor that includes redundant power supplies and boots to the last known state in five seconds. The unit can be operated stand-alone, controlled directly from a Euphonix console, or it can be fitted with software allowing control from an ES-Control-capable router controller. It provides 12 MADI inputs and 12 MADI outputs.
In Euphonix routing systems, all studio sources and destinations, as well as console signals, are converted to MADI. MADI (AES10) is a serial digital format that allows 56 digital audio signals (48kHz/24 bit) to be sent down a single 75Ω coax. The SH612 is, therefore, capable of handling routing of up to 672 inputs into 672 outputs.
Because signals are converted to MADI, the original source and destination format becomes transparent for the user. Additionally, the SH612 is based on a TDM backplane, which allows AES/EBU pairs to be separated and reassembled at will. For instance, a camera mic and mono program can be sent to the stereo AES/EBU input of a VTR by simply operating the router panel in the tape room.
Euphonix consoles use the SH612, a 2RU MADI routing unit that features a large front-panel control wheel, status lights and sync selector.
Low-cost signal distribution
In basic systems, the SH612 is configured to be controlled by the console. However, in broadcast facilities, where independent console routing is required, an additional SH612-ES is deployed and connected to the router controller. The units are identical except for mode of control.
When specifying independent routing systems, it is necessary to duplicate source signals across both systems. In many installations, this requires a separate DA for each signal source. Here, the advantages of using MADI as the native audio format become clear. Because MADI is electronically similar to SDI video, it can be run through standard SDI distribution amps. Therefore, a multichannel front-end MADI converter (analog-to-MADI or AES/EBU-to-MADI) can be inexpensively distributed to both routing systems via a single SDI DA.
Considering the number of signal sources in most facilities, the cost savings can be substantial. Furthermore, this guarantees that the required sources for the facility are equally available to both the audio mixer and panel controlled router system.
Independent router systems invariably require some level of interconnection. As the audio operator builds isolated feeds in the console, they frequently patch into the facility router, where the facility engineer must associate them with video sources for tape operators and other production personnel. The number of audio router inputs available is usually limited by the installation budget as each interconnection requires purchase of a console output circuit, router input circuit and associated patchbay real estate.
Interconnecting two routing systems merely requires patching one or more console MADI outputs to router MADI inputs via coax cables. A single coax allows 56 console signals to be placed on the router. Two or three coax cables enable the audio operator to make available all significant console outputs (main busses and aux busses) as well as many direct outputs. Manual patching is no longer required, and show setups can be saved and recalled from a file.
Digital audio console router integration provides the audio operator and the panel-controlled router operators independent control of every source on the system. The benefits are substantial.
Sharing a single set of audio converters for the mixing console and mobile/facility router can save thousands of dollars. Setups can be stored and recalled, eliminating the need for manual patching.
In addition, the audio operator no longer needs to patch console output busses to the destinations. Console output busses such as main program, aux feeds and IFBs automatically appear as sources on the router. Engineering then has full control of all audio sources from any router control panel.
Finally, the audio console and panel-controlled router share a single set of audio frames — exactly half of what is often procured. A comprehensive Euphonix digital audio system typically weighs less than 500lbs, making the solution perfect for trucks and remote applications.
Dave Hansen is VP strategic accounts, Dave McClure is product and technical specialist, and Andrew Wild is VP marketing for Euphonix. Roger Maycock is a technical writer.