K-array Loudspeakers Make the Grade in Oxford's Sheldonian Theatre, Bridging the Present and the Past

The Sheldonian Theatre in Oxford is among the city's -- and indeed England's -- most prized performance jewels. Designed by Sir Christopher Wren, one of the most highly regarded architects in history, and constructed between 1664 and 1669, it is still very much a part of Oxford culture and is used not only for music concerts, but also degree ceremonies for local university students, celebrations, lectures, and a number of other events. Recently, over the course of a painstakingly detailed restoration, a K-array loudspeaker system was installed to help bring the acoustics of this priceless architectural gem into the modern age.

Among the Sheldonian's unique architectural details are its arch layout and a large cupola; its shape allows it to be used in a variety of ways. For example, during de-gree ceremonies, a presenter will typically speak from one side of the theatre, while during conferences, speakers might address the audience from the opposite side. For each event, a decision is made on whether to involve all or part of the seating on each of the theatre's three levels.

Since the interior restoration included delicate finishes and flourishes, a core requirement in the installation was to ensure that the sound system would not interfere or otherwise obstruct its unique architectural details. Additionally, the loudspeaker system needed to perform across variety of performance and event applications, while delivering an extremely high standard of audio quality. The chosen K-array system, distributed by Sennheiser, was able to gracefully meet these requirements.

"We had to design a system which could work in both directions, with various combinations of loudspeakers used at different times," said Brian Hillson, managing director of B+H Sound, the company responsible for designing and installing the new system. B+H Sound installed 12 KV50W compact line-array modules comprised of eight one-inch neodymium transducers and two KKS50W bass line array systems, powered by two KA7 compact amplifiers and one single KA10.

The KV50W was able to provide even sound coverage while minimizing reflections -- which was important considering the semicircular shape of the space and the three superimposing orders of tribunes. The 12 speakers were discreetly placed along the handrail of the stairs leading to the organ, as well as on the doorframes and at the sides of the buttresses positioned on the ground floor and third floor. The chassis themselves were then painted to match the colors of the theatre, making them almost invisible. The two KKS50W units were then hidden within the stair structure.

"With DSP programming at the front end, the speakers could easily be controlled to suit any particular application, depending on which orientation the theatre is used in," Hillson continued. A series of presets was created so that the theatre's custodian can pre-select them depending on the intended use of the theatre.

The project was an important work of "technological restoration," carried out in close contact with both the contractor and the university building surveyor. "One of the pro-fessors, and chair of curators who had been involved in the project came in and asked where the speakers were," says Hillson. "That to me said everything about the advantages of using K-array."

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