Limehouse Studios — the £10 million TV complex — could soon be demolished after fewer than three years of programme-making for ITV, Channel 4, the record business and industry.

A group of American institutions and businessmen is eyeing London as the base of a new European centre for commodity and futures trading — a departure from the traditional City specialities of banking, insurance and equity business.

The 2¼ acre Limehouse site is slap bang in the middle of this proposed new financial empire.

'We've already made it clear that they would have to build around, over, or underneath us,' said studio managing director, John O'Keefe. But all of these options seem rather unlikely if the scheme goes ahead.

'The consortium concerned has accepted that it would have to re-build and re-equip Limehouse if we agreed to move,' said O'Keefe.

Although O'Keefe welcomes the wealth and importance the scheme could bring to the area, he points out that the Limehouse Group, which includes a production division based in central London, is unwilling to surrender its 197 year lease on the Development Area site without due recompense.

'Replacement would cost in the region of £15 million plus, quite apart from the existing property valuation and any loss of earnings caused by a move,' O'Keefe explained.

The first the firm knew of the grand proposal came when the GLC unexpectedly withdrew planning permission for the development of the west facing half of the premises.

Despite what some would regard as an awkward location, O'Keefe calculates that some 100,000 people (including audiences) have been to Limehouse since it opened in November 1983.

If the American big boys did decide to reconstruct Britain's largest independent television production centre, it would give Limehouse the kind of 'clean sheet' that most studios or video facilities would welcome — a fresh start with upgraded equipment, improved interior design and a revitalised image. But Limehouse reckons it got things pretty well right first time with its youthful riverside complex.

Limehouse's most innovatory aspects are in the sound department. The mirror-image control rooms, nominally overseeing each of the two studios (which central patching make virtually interchangeable) are equipped with Calrec 'M' series desks. Both are switchable between three modes — Broadcast, Record and Remix. This allows any of these functions to be carried out in the same room and, more importantly, in the same acoustics. This is in preference to the separate transmission and remix/dub areas more commonly found in a conventional television set-up.

Studio one (which at 560 metres squared is double the area of studio two) has a 48/24 desk input; studio two a 36/24. Each has an unusually large output vocabulary — eight sub-groups, four main output groups and eight auxiliary outputs in addition to route-ing for each studio's 24 track Otari transports, which use Dolby SP series noise reduction and can be linked together for 46 track work.

These output groups configure to one mono output and a choice of two stereo outputs for recording or transmission — the latter being possible through land-lines to the British Telecom Tower (or Post Office Tower as it was known).

There is also a Soundfield mic — another piece of Calrec hardware — permanently linked between studio one and its control room. This was a development made in support of the UK's Ambisonics system, which provides an entire surround-soundfield including vertical information.

Ambisonics has been supported by the government-funded British Technology Group for many years.

All the mathematics for this radical departure from conventional microphone techniques were derived by Mike Gerzon and Peter Craven at Oxford University. Professor Felgett of Reading University incorporated this into his B-format Ambisonics surround-sound system. Felgett then asked Calrec to design a suitable microphone for B-format Ambisonic pickup.

Limehouse has installed a subsequent product — the £3,000 Calrec Soundfield Mark IV. This has an uncanny ability to have its polar response adjusted by the judicious mixing of its four separately recorded outputs with the result that its apparent position in space can be defined after the event!

'We've terminated the link-up at the catwalk level, where the full acoustic of the studio would be appreciated in symphonic work,' said sound chief, Ron Payne (who won a BAFTA award for work at the Glyndebourne Opera House). 'But the decoder is portable, so the mic can also be used in studio two.'

Another innovation the financial whizz-kids would have to take into account if they ever produce a Limehouse clone, is the Philips variable acoustic system (Multi-Channel Reverberation or MCR) in studio one.

The electro-acoustic MCR system, which has never been installed in a TV studio before, uses 80 tuned amplifying circuits with mic and loudspeaker elements in the walls. Payne has lined the walls with fibre and concrete panels developed at Salford University. 'They're very absorbent and a third of the price of conventional panels,' said Payne. It all results in a variable reverb time from 0.8 (with the system switched off) to 1.4 seconds with the ganged master volume control at maximum.

According to John O'Keefe, a famous opera singer had refused to sing in a TV studio because of the bad acoustics normally associated with such an environment. The tendency is for everything to be as dry as possible to absorb off-screen sounds from the cameras and to dampen audience noise.

After auditioning in studio one with the MCR system in operation, the opera singer agreed to perform at Limehouse. As with other operatic productions, the orchestra was put in studio two with foldback to studio one, and in this case a Sony 3324 digital multitrack was hired in to record the result. O'Keefe claims that the MCR system contributes very little ambience to the downline mic signals, particularly where close miking is involved (as is usually the case), but it can make a great deal of difference to the performer and hence, presumably, to the performance.

For audience and orchestral ambience, both studios have gantries which allow high level rigging, while studio one also has a catwalk above the lighting steelwork for suspending mics over the studio. Each level has its own facility boxes which, when added to the floor terminals, gives a total of 63 mic lines in one and 42 in two. For stage pickup each studio has a permanent radio mic installation from Micron. 'Most studios hire RF units, with a lot of messing around with batteries, but we've got our own built-in rack-mounted system,' said Payne.

The Micron, with standard pocket and hand-held transmitters, uses a 'diversity' system where the best signal from two receivers is automatically selected.

During post-production, a SMPTE time code is fed to two slaves — usually one of the 24 track machines and one of the two Studer B67 two tracks — by a rack-mounted Sony U-matic via the Q-Lock computer. Frame accurate commands, including drop-ins on the 24 track, are programmed and the final track laid back onto one track on the line VT.

The whole complex is engineered for stereo, with programme sound sent to the Central Technical Area for VT recording or broadcasting live via BT Tower's music line/microwave links. There are incoming channels for accepting insert material which could include phone-ins.

Each control room has an EMT 938 disc player, two Soniflex cartridge machines and a rack-mounted Nakamichi cassette deck with self-adjusting azimuth.

Effects include an AMS DMX15 digital delay and harmoniser, AMS RMX16 digital reverb, and a Teledistort. This allows flipflop switching from normal to restricted bandwidth to be made between two scenes on the vision mixer, with all the crackles and relay machine-guns added later from archive FX tapes.

Examples of the studio's high-tech approach run throughout the complex, but the lighting system is particularly intriguing. Each studio is controlled by a computerised Rank Strand desk with endless edgewheel faders — an idea which somehow never took off in sound — monitored by what at first sight looks like an airport flight indicator at eye level. In fact the VDUs show a list of all the lights and their levels. These can be assigned to groups and crossfaded between user-defined 'snapshot' mixes with remote control available from the studio floor.

This remarkable system also stores programmed instructions for the motorised lighting hoists.

Each hoist can lower lights right down to the floor, so instead of scrabbling around on a catwalk the lighting staff simply lower the hoist to ground to change lanterns. Hoists can also be operated either individually or assigned to a group, and each carry a PA and video outlet for A/V applications.

One unusual aspect of the vision control arrangement is that clients sit in a separate room behind the control room with a double glass partition and monitor. This gives the creative staff much more breathing space.

Apart from the lack of a presentation studio, which could easily be added, Limehouse is effectively a TV station without a franchise. In 1990, when more franchises will be handed out, Limehouse could well be among the contenders — even if it has been moved across the gaming table to another part of town by the money men.