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Redesigning audio monitors for future broadcast

Mike Law of BCD Audio talks to Kevin Hilton about updating that stalwart of sound production, the monitoring unit, to meet the demands of new television broadcast technologies.

The audio monitor has always been part of broadcast set-ups but it’s often overlooked by the majority of people working on a programme. That’s partly because it’s usually hidden away in an equipment area or a corner of the master control room (MCR).

But monitoring is a critical part of the production process, allowing engineers and operators to check that what is arriving at the studio is in the correct format and gets to where it should be. The number of feeds coming into a broadcast centre, and the amount of channels each contains, is now making greater demands on the humble audio monitor, further complicated by the increasing shift to all-digital operations.

Mike Law, chief executive and designer of BCD Audio, comments that the need to incorporate new technologies into audio monitors has signalled a definite change from the past. “The focus is now on digital input sources,” he explains. “Every monitor used to be analogue, with perhaps an A-D converter, but now everything is the other way round. The only analogue things on a modern monitor are the headphones and the loudspeaker. Even the power amps we’re using now are Class D conversions, so that side isn’t analogue any more.”

BCD Audio has been a fixture on the UK audio market for many years but, typically for a company making the type of equipment it does, it has never had much of a profile outside of the engineering fraternity. BCD’s core products include tone generators, interconnectors, converters and measurement units but it has also produced audio monitors and production equipment that are part of everyday programme making.

The prime example of this is the PAM (Presenter Audio Monitor, pictured), which has just gone through a 21st century make-over and is being installed at BBC facilities in the “new” Broadcasting House (BH) W1 centre and facilities at MediaCityUK (MCUK) in Salford Quays. The original PAM was designed 15 years ago and installed at BBC Television Centre but time and operational requirements have moved on.

PAM Mark I had a six-channel audio mixer with a headphone output at the out-station and was connected to the broadcast infrastructure using a large multicore cable. Law explains that the new version “centralises the audio mixing to digitally controlled Eurocards within a 3U rack”, which allows simpler out-station connection to wall-boxes via a smaller four-pair cable.

This allows presenters to control their own mix of the programme, count and talkback feeds using an assignable panel under the desk on the set. Two versions are available: the PAM-4, a basic unit with mixer controls for use with a wireless headphone system; and the PAM-6, which has the mixer plus local headphone amp and limiter.

BCD’s involvement with the W1 and Salford projects has proved fruitful in adding new products to its portfolio. Also going into operation soon are the AMU (audio monitoring unit) and the DAVE (digital audio/video editor). The AMU is an eight-channel device with inputs for analogue, AES digital or embedded audio signals, which are monitored visually on PPM (peak programme meter) ballistics. It is designed to be used by producers in studio galleries, which is why, says Law, there are only eight-channels of audio. “In theory we could add more channels using extra switching but the idea was to keep everything simple.”

DAVE is intended to be used at journalists’ desks and features HD video, with the capability to strip out the audio so it can be worked on using an integrated sound mixer. BCD designed the mixer but the audio monitoring component was supplied by Newbury Systems. Law says 28 DAVEs have been shipped to W1 and are currently being “assimilated”.

In designing monitoring equipment for this new technological era Law and BCD have embraced FPGA (field-programmable gate array) technology for processing instead of DSP. “Once we dumped DSP we found we could do more in the unit, ” Law says. “This includes interfacing as well as general processing.”

Law is also contributing to the drafting of a new AES transport standard for multi-channel audio, with the project designation AES-X196. “I felt I could offer something to this,” he comments, although admiting this work and his new-found higher profile in publicising his work has dragged him away from his natural habitat, the development workshop. Despite that it’s more than likely that Mike Law will find time to get back there and continue to contribute to a relatively unsung area of audio operations.