Broadcasting 3-D Sound

It is no secret that Sound International is very much an advocate of the Ambisonic/NRDC surround sound system, developed in the main by Peter Fellgett and Michael Gerzon, and now emerging as the way to capture sound in three-dimensions. Unfortunately, unless you are a close friend of either of these illustrious gentlemen, or rich and influential enough to have in your possession one of the Calrec Soundfield microphones (see SI August issue, p17) there is very little chance of you actually hearing just how impressive the system is. I am sure that once more people have had the opportunity to compare the Ambisonic system with conventional 'quadraphonic' (or 'four-source' systems, which is a better description for them) - and experienced the staggering realism that true surround sound offers - then studios will be throwing away their pan pots and learning all they can about A-format, B-format, UHJ and all the other essential concepts and vocabulary of the new Ambisonic system.

It is timely, then, that in late November the Independent Broadcasting Authority laid on a series of experimental broadcasts of surround sound material, using the '2½-channel' broadcasting technique. The extra 'half-channel' is broadcast with reduced level and bandwidth by 'quadrature' modulating the 38kHz sub-carrier already present for stereo programmes (as with the BBC matrix HJ system), the additional half channel is said to improve the bass response and stability of front and rear images. However, that's only part of what the tests were to prove — signal-to-noise ratios and other parameters also being under investigation — since the overriding consideration as the IBA begin seriously to come to grips with the Ambisonic/RDC surround sound system (at long last) is what it will do to reception of such programmes in mono and stereo. Because if you sacrifice compatibility to your existing listeners for the sake of a few audiophiles (and it will only be a few until suitable hardware becomes available) then advertisers — it's commercial ILR remember — will be the first to object.

The surround sound tests were broadcast by Capital Radio, London's all-music independent local radio station, and comprised three sessions of very different material. On Friday night the station put out an hour of a Suzi Quatro concert recorded earlier in the month at the Hammersmith Odeon. The following Sunday, as part of its classical programme The Collection, Capital broadcast part of a concert by the Royal Philharmonic Orchestra recorded at Croydon's Fairfield Halls. The concert comprised two works: the suite from Rimsky-Korsakov's opera, The Snow Maiden, and Tchaikovsky's Sixth Symphony, Pathetique. And finally on the same Sunday, the station entertained London to part of an appreciation for the late Welsh poet Dylan Thomas, recorded earlier at the Wembley Conference centre, and which consisted of readings from Thomas' work accompanied by musical interludes from the Stan Tracey Jazz Band.

An odd choice of material indeed, but at least it encompassed a wide range of tastes that rock, classical and jazz fans could get off on. And it must be remembered that only a couple of dozen people (including myself I am fortunate to say) could listen in true surround sound, the rest of London being merely guinea pigs to see if the stereo was at all affected by the extra manipulation of their two channels. (Thanks once again to the IBA engineering department for the loan of a specially modified Yamaha FM tuner and hand-built 2½-channel decoder.)

So to the acid test: what did it sound like in stereo and/or surround sound? I am sorry to have to report that the trials were very disappointing. Now whether or not the IBA quite came to grips with the full facilities of the Calrec Soundfield microphone they used on Fairfield Halls and Wembley performances, or - more likely - are still getting the bugs out of the experimental mobile used to record and mix down the tapes, I'm not sure. But 11 out of 10 for initiative and minus a million for possibly rushing into a trial such as this without enough practice. Sorry lads; nice try.

There's no real point in detailing all that we found wrong with the broadcasts because very few SI readers will have had the chance to hear the programmes as we did, apart from the necessary comment that the soundfields reproduced in our listening environment (a friend's living room) were most unconvincing. I am reluctant to point the accusing finger at Capital Radio's Mike Sykes, who remixed the multitrack tapes into surround sound aboard the IBA mobile. His task was not without its own particular problems, I'm told, and the material was put together in less time than the team would have liked.

It seems to me that when further tests are organised by the IBA in early 1979, it would be much more sensible to try and organise a larger gathering of people, including SI readers of course, who could listen to both the original recordings of the concerts to be broadcast, as well as the broadcasts themselves. That way the two stages can be isolated and critical assessment made of both the surround sound system and the 2½-channel broadcasting format. I would suggest that the material for subsequent tests make better use of the surround sound medium. At no time during the November experiments was a vocalist or instrument caused to move within the soundfield — a marvellous opportunity for intricate panning as ever presented itself. More disturbing was the fact that none of the concerts were particularly exciting events in stereo (I checked) let alone surround sound; there again what live event with stage and audience has ever been captured satisfactorily on tape? How much better to simply take a Soundfield microphone into an acoustic full of interesting sound and movement. Even a ride on, for example, a tube train, let alone an outdoor performance by an acoustic ensemble would be infinitely preferable to what I heard last time around.

More to the point, have you, gentle SI reader, got any useful ideas/projects in which we could try and interest the IBA? Within reason, they are willing to involve during subsequent experiments anybody who has sensible suggestions to contribute, both on the performance and technical side. But, please, write to us at SI and not the IBA direct, because they just don't have the machinery to enter into correspondence at this stage in the game. We also plan to put together a couple of articles later in the year which will describe in greater detail how the Ambisonic/NRDC system works, and the major advantages offered by surround sound. Mel Lambert

Glyn Johns' Top Copies

Top engineer/producer Glyn Johns has recently set up what promises to be one of the best tape copying facilities in the country. The facility, developed in collaboration with A&M Records, should fulfil the need for top-quality individually-produced cassette copies (as opposed to the copies produced by high-speed duplicators which tend to lack top and add noise) as well as reel-to-reel reproductions.

To realise these aims, Glyn has fitted out the copying suite, in the old Manticore Cinema in London's North End Road, with three Studer A80 machines and the rather lovely Landberg 3-head cassette recorders. For further information contact Anna (she of Olympic - Studios that is - fame) at The Old Manticore Cinema, (Contact Details).

Inject an EMO

The March '78 issue of our companion magazine Studio Sound carried a review of the prototype of a new DI box, notable for its compactness and solid construction (no it doesn't fall apart when you drop it, like the ones I used to build... ) made by EMO Systems of Durham. The box is now in production, with the addition of an Earth Lift switch which wasn't present on the prototype. The die-cast unit is also nicely silk-screened so you know what all the sockets do. An Earth Lift switch, by the way, is useful for avoiding distasteful hum loops and other earthing problems. If you get a hum, switch the switch so it gets better(!). The unit is available from Turnkey (you know good ole Turnkey, Andrew Stirling an' all that, suppliers of cost-effective gear to all you small-studio freaks... - ad lib and fade) and retails at a tidy £33 including the dreaded VAT. I tested it out and it's very nicely low noise, and matches into most normal amps and desks. Instrument ins and outs are on ¼in jack sockets, with a male XLR socket for the balanced line feed to the console of your choice. A good buy for all of us who can't afford a separate control room and need to play and record in the same room. High quality sound is yours, and not a mic in sight (just don't try plugging it into your Steinway).

Turnkey, (Contact Details). Say hello to Andrew Stirling from us (hi there).