The Empire Strikes Back with Driverack

Thursday, 27 July 2006
The Empire Strikes Back with DriverackL-R: André Mort with Laurence Claydon at the dbx DriveRack4800.
USA - dbx Professional Products, a Salt Lake City-based manufacturer of professional signal processing products and a division of Harman International, has announced that five of its premium DriveRack 4800 loudspeaker management processors have been selected to control a JBL sound system in one of London's premier cinemas.

The Empire Cinema in Leicester Square, which hosts many of the UK's film premiers, has undergone a much needed equipment upgrade following its takeover from UCI by the newly-formed Empire Cinemas Ltd. According to The Empire's marketing and development manager, Kevin Anderson, the investment has run "well into six figures".

Technical manager for the Group, André Mort, says that the requirement was for a THX-approved system, and appointed Bell Theatre Services (BTS), who have a long association with the venue, to come up with a specification and undertake the installation. As a result, the cinema supports all standard analogue and digital surround sound formats.

"People have often complained about the sound quality here, and since this is our flagship venue, we wanted to meet certain criteria - specifically THX approval - to satisfy distributors. At the same time we wanted to increase the screen size (to 18.2m x 7.68m) to be in proportion with the theatre."

BTS's digital cinema specialist and system designer, Laurence Claydon had originally considered other loudspeaker management systems but his decision to opt for a digital infrastructure sold him on the DriveRack 4800.

"I chose dbx, partly because it has eight outputs, allowing us to run a four-way stereo pair, as well as the 24-bit 96kHz processing engine, which several movie companies are now requesting as standard spec. The fact that the DriveRack 4800's had also just been approved by THX was an additional bonus, and extremely convenient!

"I knew that other dbx units had been THX approved and when I referred the 4800 to them they were happy to endorse it." He added that the system at The Empire was one of the best that THX had certified.

The capacity of the five dbx processors is being severely tested since they are being asked to manage a newly-developed, four-way, JBL custom system - the first of its kind in the UK.

Five JBL 5632's provide L/C/R, as well as inner left and inner right imaging. This is reinforced by 16 x JBL 4645C sub woofers and 42 x JBL 8340A surround speakers.

Claydon says: "We've been generous with subwoofers; there's no significant power compression and we have achieved good LF extension. Each surround speaker has its own amp channel and these are delayed in banks.

"We have matched the natural curvature of the lower surround on the rear wall with the upper to create great audibility at the rear and excellent channel separation. A real issue here in the past had been the audibility falling off eight rows from the back."

The DriveRack 4800's are individually assigned to left/right; centre, sub and booth monitor; inner left/inner right; side surrounds and bank delay; rear surrounds and second bank delay.

The system is powered by a combination of five Crown CTs 2000, 13 x CTs 3000 and six CTs 8200, each of which drives an individual surround loudspeaker. According to Mort, the new JBL/dbx/Crown combination raises the sound output from the previous 13kW to 56kW.

The DriveRack units operate under Harman's HiQnet digital network protocol and one of the real advantages of the CobraNet system has been the ease of software configuration, says Mort. "We actually put a PC in rather than have to worry about laptops and we have control software for the Dolby CP650 gear, HiQnet, Sony SDDS and even DLP projector onscreen."

Setting up the dbx DriveRacks had been completely intuitive, while Harman's System Architect control and monitor software is "a joy to work with," says Laurence Claydon. "We have been through a couple of different EQ set-ups and fine tuned the gain structure -


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