In the region of a thousand JBL Control 26CT ceiling speakers have been distributed throughout the concourse of the new Westfield London Shopping Centre — the largest inner city shopping mall in Europe.
The 100V line 2-way loudspeakers were selected as part of a multibrand solution by installation contractors, Siemens. AMS Acoustics were employed as Siemens’ acoustic consultants to interpret and realise the Westfield specification.
Set on two floors, the 43-acre development in West London, which cost £1.7bn, boasts 265 shops ranging from international and couture brands to ‘anchor’ High Street names, as well as a 14-screen cinema, 50 restaurants, a gym, a spa, a library and a Winter Garden under its undulating, energy-efficient roof.
Recess-mounted into a suspended ceiling under this roof, the JBL Control 26CT’s broadcast sound throughout the sprawling malls.
Said AMS Acoustics’ Tim Gully, who co-project managed the installation, “The JBL Control 26 loudspeakers were selected following an assessment of the reproduction quality required by the client, and a cost benefit analysis.
“Several models from other manufacturers would have met the technical criteria but the JBL came out as the best choice when all the factors such as sensitivity, quality, amplifier requirements, fitting and aesthetics were considered. Having worked with Harman products on many other jobs we were perfectly happy with this.”
Principally, the public address system needed to meet the British and International standards for intelligibility while remaining entirely discreet, he emphasised.
The loudspeakers take mic and BGM feeds (from multiple CD players), while specific areas have audio patch panels to enable additional equipment to be fed into the network. But AMS Acoustics’ primary concern was the voice alarm protocol, and ensuring it complied with safety standards.
The system is thus divided into two distinct parts. The PA only is directed to back of house while full PA/VA services the front of house areas and escape routes. “In the event of an alert all broadcasts to the zones concerned — as well as those adjacent — are muted and just the evacuation/alert is broadcast,” Tim Gully explains.
The design target SPL for evacuation messages was set at a maximum level of 93dBA and for general operation the SPL of the system is controlled by ambient noise sensors, which fix the SPL to 10dBA above the background noise levels.
Nearly 250 differently-rated power amplifiers, serviced from five equipment rooms, drive the overall system, with all rack rooms networked using a redundant fibre network.
The AMS Acoustics design led by Lorenzo Morales, are satisfied that the specification has been met and that the Control 26CT’s are fulfilling the role expected of them in providing high intelligibility, and good music reproduction too.
AMS Acoustics Principal, Helen Goddard said “I was delighted with the audio I heard when I arrived during the first day that Westfield London opened. Our clients expectation was exceeded which is always pleasant outcome. It affirms our belief that a thorough design process, along with good supplier support adds value to any project. We appreciate the excellent product and support given by JBL, particularly Sound Technology in the UK.”
