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Studios & Recording

Three pages of news including Bowie synthesisers and goodies from APRS.

Ambisonics: Sound Sense

The new Calrec Soundfield microphone, first shown at AES Hamburg and discussed in SI 2 (New Dimensions In Sound Recording), was on show once more at APRS, but with several modifications. The new CM4050 mic and CS5014/3 control unit (£800 and £1300 respectively) offer the entire range of possibilities mentioned in our earlier report, and a few more: a single output corresponding to any mono mic with any polar diagram (of the 'first-order' type, omni, cardioid, hypercardioid, or figure-eight) which may be panned or tilted in any direction (during or after recording); a pair of outputs corresponding to a stereo pair of any first-order microphones that can be pointed at any angle to each other, panned and tilted; a set of outputs corresponding to four microphones, adjustable as before, to interface with existing so-called 'quadraphonic' systems; and, of course, the B-Format output that the mic produces can be used, under control of the pan, tilt, vertical and forward dominance settings, directly for the encoding and reproduction of Surround Sound in accordance with the NRDC system.

The control unit also offers gain control, switching and monitoring facilities. The construction of the control unit is modular, and a number of modules may be left out without affecting the unit's stereo capability. So you can leave out bits until you can afford them, and still have a 'super stereo' mic on your hands.

(Click image for higher resolution version)

The diagram illustrates the component modules in the system and what they do.

Meanwhile, the development of practical applications for the Ambisonic NRDC system moves on apace. Mike Gerzon tells us that the system, previously referred to as 45J, is now called UHJ, or Universal HJ: U from the Nippon-Columbia UD4 system, which is now incorporated, H from the BBC's Matrix H broadcast ambisonic system, and J for the NRDC and 45J. The UHJ system specification is, in some ways, a compromise between the three component developments, but Gerzon, Fellgett and co have made a few updates to the design as well, so it's not so much a compromise, more an improved synthesis.

And talking of Gerzon, Fellgett and co... we were a little forgetful in our June news item on Ambisonics: while we mentioned Mike Gerzon at the Mathematical Institute in Oxford, we forgot to give due respects to Peter Fellgett at the University of Reading; these two — and several others — are responsible for the development of the system which, with luck, will become the industry standard for surround-sound. There is now a (small) budget from the NRDC for commercial recordings, which will primarily be of classical material: in fact, they hope to get the Last Night of the Proms, if contract conditions allow. What better demo record to release than a best-seller? But there is interest in the rock field as well, and equipment is being prepared to deal with the rather different conditions encountered in rock recording. We at Sound International would be interested in hearing from bands who feel their music would benefit from a proper surround-sound recording, using all the modern studio techniques but with the added practicability of constructing an album in the UHJ format. We'd also like to hear from record companies who would be interested in sponsoring recordings of this nature, or just 'getting involved' in a project which promises to be one of the most significant recording developments for many years.

In the broadcasting field too, there is a lot of activity. Apart from BBC transmissions, the IBA are interested in the system: sufficiently to commission Alice (Stancoil Ltd) to build a mixer for their new experimental Ambisonic mobile unit. The mixer will be based on the Alice Custom Modular system, with 20 inputs (mono) and 5 ambisonic (B-Format) inputs, plus UHJ decoder monitoring and 16-track interface. The design work is being done jointly by Alice and the IBA; the latter being responsible for the rather fiddly ambisonic panpots, among other things. The mixer is intended to be installed shortly for a series of ambisonic recordings in the autumn. It's good to see the system becoming accepted so rapidly.

MXR Compander

Under subtle electronic torture in our reviewer's electronic obstacle course of a front room is a new and very interesting offering from MXR: a compander designed for noise reduction. As you probably know, there are two basic ways of reducing noise on a tape, or whatever. One is the Dolby-type approach which involves splitting the signal into four frequency bands (in the case of the A system) or not (in the case of Dolby B) and applying variable-gain frequency dependent amplification in the side-chain of the system. The other method, as used by dbx, involves compressing the signal being recorded, and expanding it on replay. The latter gives far more noise reduction, but can suffer from 'breathing' or 'pumping' when the compression/expansion circuitry is working hard.

However, dbx systems are not cheap, and although they are becoming increasingly popular in smaller studios, there have been several attempts to produce the same effect for less. The basic problem is to get a good linear compression curve and a matching expansion on the way back out of the machine. Dbx do it with a very clever system of pre-emphasis and de-emphasis, and close-tolerance circuitry; and they're very good at both of these. But expensive this type of unit is.

Popular contender for the home-constructors do-it-yourself compander market has always been the NE571 compander chip: but this has several problems, not least the fact that it is very hard to get both channels to track together.

However, it is this chip that MXR have used in their new Compander unit: reputed to be 'subjectively compatible' with dbx. The unit has no pre- or de-emphasis, but, our resident electronic microscopist tells us, it's very effective. Dynamic range is given as 100dB, and frequency response 30Hz to 20KHz +1dB. We'll be looking at it in greater detail next month, but until then, have a look at it. The good thing is, it's half the price of dbx (UK price: £168-67).

MXR professional products are handled by Atlantex Music in the UK: Contact Bob Wilson at Atlantex, (Contact Details).

Studio Time...

On display at APRS this year for the first time was a novel digital studio clock from Quadrant Electronics. The electronics is mounted on a single square board, with a 24-hour hours and minutes readout in the centre, surrounded by a ring of 60 red LEDs which indicate the seconds. Each LED lights up in turn until all 60 are illuminated, at which point the seven-segment display advances one minute, the ring of LEDs is extinguished, and the cycle begins again. The board is mounted behind a red perspex cover which just about allows you to see the innards, and is finished off in wood. The clocks can be run independently or slaved to a master: ideal for studio applications — and maybe home use too.

For further information, contact John Andrews at Alice (Stancoil Ltd), (Contact Details).

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Sound International - Copyright: Link House Publications


Sound International - Aug 1978

Donated & scanned by: Mike Gorman


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