Achieving the impossible

Oct 11, 2010

Installing necessary modern day technical infrastructure into historic buildings is always a difficult and contentious issue. This is especially true when the architecture is so precious that, not only is any visual sign of the new equipment undesirable, but concealing it becomes extremely difficult because any impact on the building’s fabric must be kept to an absolute minimum. However, this installation of an Ampetronic induction loop system in London’s Freemason’s Hall has proved that the impossible can be achieved.

Located in Great Queen Street, Freemason’s Hall is the headquarters of the United Grand Lodge of England - the governing body of Freemasonry in England. Built between 1927 and 1933, the hall is the third to be located in Great Queen Street and was constructed as a memorial to the 3225 Freemasons who died on active service in the First World War.

The centrepiece of the building is the Grand Temple, a chamber 123 feet long, 90 feet wide and 62 feet high capable of seating 1700, which has recently had an Ampetronic induction loop fitted by Surrey-based contractor Scanaudio.

As well as the main ‘floor’, the Grand Temple features a balcony on three sides and the Ampetronic system, powered by a pair of ILD1000G loop amplifiers via an SP5 phaser, was required to cover the whole chamber and to meet new British Standard requirements for induction loop installations.

However, discreetness was imperative because of the sensitivity of the fine architecture and the fact that, as well as Masonic meetings, the Grand Temple is used for a range of other functions, including filming contracts.

“The Grand Lodge is one of finest art deco buildings in London, so we had to be extremely careful,” says Scanaudio’s Dee Couchman. “It was made even more challenging by induction loops not even being invented when the building was originally constructed, so of course they didn’t allow for them in the infrastructure.”

Ampetronic took on the challenge of designing a system that ensured maximum coverage, but made as little impact as possible on the fabric of the building. “Structural metalwork invariably has a significant negative effect on loop performance”, says Ampetronic’s James Bottrill. “Bearing in mind the restrictions placed on installation locations by the ornate architecture, and knowing that Freemason’s Hall is a steel-framed structure with concrete floor slabs throughout, a site survey was considered essential if an acceptable result was to be assured. The data collected on site enabled us to design a system which would assure good performance, whilst minimising the complexity of the installation.”

The actual installation process was no less challenging, one of the major problems being that the wrought iron legs of the seating trap a lot of the carpet beneath them, so the installation team was unable to lift many carpet tiles at once in order to install the loop.

“We used a combination of copper tape and 2.5mm² cable, which was necessary because of the restricted access to the under-carpet areas, so we could discreetly glue or stapled cable in some areas,” says Dee.

With the loop amplifiers installed in an existing A/V equipment rack, the only part of the Ampetronic system that is visible is a one metre length in an unobtrusive plastic extrusion, which links the balcony loop to that on the floor of the hall.

Feeds for the induction loop come from the Grand Temple’s installed audio system, which comprises wired and radio microphones, an auto mixer and compact loudspeakers.

“The combination of a suitable microphone scheme and a carefully designed and installed induction loop system will be of great benefit to hearing aid users attending functions in this spectacular building,” concludes James.

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