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From the Fire

Oct 15, 2013 3:50 PM, By Cynthia Wisehart

Restoration AV

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St. Ursen

After an extensive fire forced a major cleanup and restoration to the 18th century St. Ursen Cathedral, the already long reverb increased—just one factor that helped define the electroacoustic renovation.

Fire is one of the most devastating events that can befall a congregation. People often feel deeply connected to the look and sound of their house of worship. The voice of the community inevitably takes on a different character as it fills a church that has been restored from fire.

This can be a good thing. While fires bring disruption and sometimes tragedy, they also bring opportunity, especially for churches with aging audio systems and acoustic properties that may be centuries old.

In January of 2011, in the Baroque town of Solothurn, Switzerland, a lone arsonist poured two cans of gasoline in the sanctuary of the St. Ursen Cathedral and ignited them. The fire massively damaged the 18th century cathedral, destroying the altar and parts of the nave and sanctuary, covering the alabaster walls, soaring ceilings, and world-renowned organ with a sticky film of soot and oil.

The timing was terrible (and perhaps intentional). St. Ursen was scheduled to host a formal consecration ceremony for the controversial new Basel Diocesan Bishop in five days. Instead, the cathedral closed to began years of renovation.

When people enter St. Ursen Cathedral today, the first thing they remark upon is the gleaming white and gilded surfaces. The painstaking cleanup (by Flury und Rudolf Architekten AG) removed the soot and oil, as well as centuries of dust—dust that had functioned as acoustical dampening in the cavernous space. “It was slight but measurable,” says Michael Chollett of Walters-Storyk Design Group. “The church measured a very long reverb in the mid-frequencies to begin with (RT60 of more than 6 seconds at 500Hz), which became worse with the cleaning.”

The diocese had already been planning a major overhaul for the cathedral with a five-year window. Design was underway at the time of the fire for things like networking, security cameras, and lighting. “The fire triggered the work to be done much earlier than anticipated,” Chollet says, “and since much had already been discussed and prepared, it was greatly accelerated—five times quicker.”

The restoration encompassed every aspect of the building: surfaces, art, lighting, HVAC, electrical, electroacoustic, even a touch control system for the 18th century bells. The central challenge of the AV design was the size of the room, especially the very large distances from the altar to the rear of the church and from the main organ and choir to the auxiliary organ. How to achieve intelligibility and sync? The “very live” room seats about 1,000 people and had to be tamed without affecting the distinctive aesthetics or changing any materialization. Further, the room presented several acoustically shadowed areas, where approximately 1/3 of congregants had been missing out on the worship experience.

The design incorporated a savvy mix of cutting-edge and traditional tools: next-generation steerable line array technology, modeling software, and good old analog signal.

By running modeling scenarios with Swedish software CATT-Acoustic (similar to EASE), Chollet says they selected a line array over a distributed configuration. “We settled on the latest generation of steerable line array,” Chollet says, a total of eight CVS Clearvoice Evolutone (2x 3000, 2x 2000 for the main playback and delays, and 6x1000 for the shadowed areas). He says the speakers have a very long-range throw, highly sophisticated steering algorithms and high speech intelligibility. “With steerable arrays, we came from broadband speakers to speakers that have higher channel count—16 or 24—and two-way high- and low-frequency drivers. These advancements make the steering more precise and give better acoustical result with music. When you’re play music you’re happy to have the latest generation of these speakers.”

The DSP is not so impressive, he says—because it didn’t have to be. “It’s not the main issue,” Chollet says. “So the decision was to go for compromise on the DSP and have the budget for the speakers.

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