Sound Technology

The world famous 13th century Salisbury Cathedral welcomes some 300,000 visitors each year — either to view the Magna Carta or attend its programme of major services, concerts, religious festivals — or simply for private worship; and they expect the sound in this reverberant space to be heard coherently and intelligibly.

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The last major sound system installation took place in 2000, but with a distribution network using outdated technology, the administrators faced the prospect of a complete overhaul.

The work was undertaken by Ed Manwaring (of EM Communications) who had been servicing the PA for nearly ten years, and latterly carrying out a succession of repairs. “The aim was to upgrade an ageing network backbone and, crucially, to vastly improve the speech intelligibility within the Cathedral, made difficult by the enormous reverb decay time in excess of 6 seconds.”

Manwaring proposed an integrated solution from within the HARMAN Professional catalogue, comprising JBL CBT pattern-controlled column loudspeakers, ideal for difficult acoustic spaces, Crown DriveCore Series highly-efficient amplifiers and BSS Audio’s latest generation Soundweb network processors with Dante networking capability to replace the original Soundweb ‘green’ boxes.

Ben Todd, Project Engineering Manager for HARMAN’s UK distributor Sound Technology Ltd, joined Manwaring on a site visit back in summer 2015.

A site test of JBL’s CBT (Constant Beamwidth Technology) CBT100LA and CBT70J line array columns with their asymmetrical vertical coverage demonstrated the system’s even coverage, while addition of the supporting subwoofers showed its potential as a performance system. Previously, the Cathedral had to hire-in systems for music events with limited success due to the dramatic reverberation times.

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A total of 42 JBL CBT loudspeakers were deployed, alternating CBT70J and CBT100LA models. A pair of CBT70JE columns provide extended bass response, whilst JBL PRX718XLF subwoofers are provided for use for performance events.

The distributed loudspeakers are driven by Crown’s new generation DCi Install Series amplifiers, eight DCi4/600 and two DCi4/300, selected for their efficiency and remote sleep facility. Crown XLS1502 amps power the CBT70J/CBT70JE combination, which is positioned at the front of the Nave. The DCi’s integrate fully with the Soundweb DSPs in Harman's Audio Architect software — a combination which has already proven successful in a number of high profile.

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The new audio network has been divided into six zones; Trinity Chapel, the North and South Transepts, the Quire, the Crossing and the Nave. They are fed from five rack positions — the main one behind the organ and two in each of the north and south triforium ‘galleries’.

The Soundweb system comprises a Soundweb London BLU-160, two BLU-120, and three BLU-100. There is a requirement for 32 inputs (CD, mic, aux) hence the addition of a BLU-BIB input expander and two BLU-BOB output expanders. All devices are connected within each rack location via BLU Link, whilst the new BSS BLU-DAN interfaces the entire Soundweb system onto a Dante network.

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“The advantage of using the BLU Dante devices was in reducing the amount of cables that have been redeployed because everything runs through the three network switches on a VLAN,” the installer explains.

While the CBTs conveniently have a selectable vertical coverage preset board for music/speech settings, Manwaring also had the task of setting the delays and time alignment for sound firing from either direction along the nave. These parameters are programmed in a matrix of delays in Soundweb.

The final piece in the Harman Professional jigsaw is the Soundcraft Performer 3 mixing console which will be used predominantly for live music and ‘special event’ productions such as Salisbury Festival. Aside from the Dante option card, it is also equipped with a MADI card to talk to the Soundcraft Mini Stagebox 32R, which meets broadcast needs by the BBC.

The entire system is controlled intuitively by the vergers, using two iPads, both configured identically, using the Harman HiQnet Motion Control Apple iOS app.

The new system delivers wholly integrated control and monitoring via Harman Professional’s Audio Architect, allowing much greater flexibility and information feedback than previously.

The installation has met all criteria, according to Salisbury Cathedral Floor Manager, Russell Cruse. “It has been a great success in terms of speech intelligibility and clarity and I have received positive feedback from the guides, vergers and clergy.

“From an operator’s point-of-view, it is much easier to use given the flexibility that the iPad controls allow.

“Overall, the whole project has been very successful.”

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October 2016

Venue

  • Salisbury Cathedral
  • World famous 13th century Cathedral

Project Team

Products

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