House Of Worship

Cochran Chapel’s Hidden Speakers Deliver Top-Notch Sound With No Visual Impact

Equipment List

Installations in historic houses of worship have their ups and downs. On the downside, integrators can rest assured that a one-size-fits-all approach will not work in these types of spaces, because the older the building, the more quirks it is likely to have. And, of course, there are always aesthetic concerns; somehow the charm and elegance of a historic space tends to be diminished by the presence of a huge, honking line array hanging over everything. But on the upside, since integrators can’t rely on their typical bag of tricks for installations in historic spaces, they’re forced to get creative with their solutions.

For an example of the creativity required to work in a historic space, look no further than New England-based integration and consulting company Balanced Input’s recent audio upgrade at Phillips Academy Andover’s historic Cochran Chapel.

Phillips Academy, a boarding school with a rich history that dates back to 1778, has produced such notable alumni as former presidents George H. W. Bush and George W. Bush, actors James Spader and Olivia Wilde, and New England sports deity Bill Belichick, among several other luminaries. Cochran Chapel, the school’s main meeting place and the setting for its on-campus worship services, has its own long history, having been originally dedicated in 1932. Following an extensive renovation in 1998 that included the expansion of the chapel’s balcony to provide seating for up to 1200, and the subsequent addition of projection screens for IMAG a few years ago, school leadership determined that a long-overdue sound system upgrade was in order, as well.

In order to satisfy Phillips Academy’s expectations, the new sound system had to be able to handle Cochran Chapel’s demanding schedule of events. In addition to hosting school functions attended by every member of the student body and faculty, Cochran Chapel also hosts weekly worship services that cater to a wide array of faiths, plus weddings, community events such as concerts and recitals by high-profile artists like Yo-Yo Ma, Bobby McFerrin and Evelyn Glennie, and speaking engagements featuring big names such as Spike Lee and Jane Goodall.

However, before Balanced Input could install a new sound system, the company first had to master Cochran Chapel’s unique architecture. “There are two lines of pillars that run the length of the building,” explained Mark Waker, the Owner of Balanced Input. “The base of the pillars is almost five feet across diagonally. Now, the pillars are the single biggest problem within the chapel, because obviously they’re massive obstructions to the passage of sound.” He added, “To give you an idea of just how much these pillars dominate the space, the school recently installed large projection screens at left and right of the altar, so people in the side aisles can see what’s going on in the center.”

Further complicating things was the sheer amount of wood in the space. “The room is a temple to woodworking,” said Waker. “It’s all wood. The only plaster in the building is on the walls starting from about 10 feet up. But you’ve got 10-foot-high wood paneling all around the room. The front of the balcony is wood, the pews are wood, the pillars are very large pieces of wood. So we had a lot of reflectivity we had to be aware of.”

All that reflectivity wreaked havoc on the intelligibility of the chapel’s old sound system, which was further handicapped by poor placement. According to Michael Crouse, Phillips Academy’s AV Manager, “The old system was a prototype of one of the first line arrays ever made. It was a very large array, and it was installed on one of the pillars toward the front. And because it was hung on the pillar, shooting straight into the other pillars, there was a dead zone behind every pillar.”

In addition, the old sound system did not provide adequate coverage to the seating in the new balcony area. “Because it was such a long throw, we had fills placed on the side walls for the balcony,” said Crouse. “But this resulted in the center of the balcony, where you have the best view of the stage, having the worst sound. There was a V-shaped dead zone there. And sound was very inconsistent throughout the space. If you fed a sine wave into the system and walked the room, you could hear all the dips and the reflections coming off the wood walls canceling things out.”

In order to compensate for the old system’s shortcomings, Phillips Academy’s AV personnel had to push the system to its limits. “We were pumping a lot of power into the space,” said Crouse. “We would have to set the system pretty much on the verge of feedback when the room was empty, and then when the room was filled with students, it would sound OK. But there wasn’t much articulation, and it was always a fight to get enough coverage and volume out of it without pushing it. We didn’t have any headroom. And, if you had a lav mic on and you stepped 15 feet off the stage, you had to dash back up to the stage because of the amount of feedback that would fill the space.”

With these complaints in mind, Waker went about designing a new system that would work in the space. “The primary goal was to improve coverage so everyone in attendance could hear the message,” said Waker. “The secondary goal was to improve fidelity and user friendliness in the system to where a speaker or performer could walk out into the audience without fearing howls of feedback.”

However, Phillips Academy’s Design Review Committee wanted to ensure that the new sound system would have less visual impact on the space than the old system. Not only did they want to preserve the aesthetic of the historic space, they also wanted the new sound system to complement the recently installed projection screens, which appear and disappear at the touch of a button. “It was a big challenge,” said Crouse. “As Mark said to me, generally if you can’t see a speaker, you can’t hear it; it has to be in line with the listener in some capacity.”

The mandate that the speakers had to be invisible limited Balanced Input’s options, and several possible solutions were discarded for various reasons. “At first, we figured that the only way we could place the speakers with any kind of effectiveness would be to cut them into the pillars,” recalled Waker. “But that wasn’t happening, even though there would have been plenty of room in there for them. Then we looked at a lot of stick speakers, but the idea of deploying multiples of them directly onto the columns was rejected out of hand.”

Cochran Chapel’s elegant wood paneling, as well as the 12 massive columns lining the center aisle, created many acoustic challenges for Balanced Input to overcome.
Cochran Chapel’s elegant wood paneling, as well as the 12 massive columns lining the center aisle, created many acoustic challenges for Balanced Input to overcome.

Eventually, Waker was able to devise a solution that would meet everyone’s expectations. Drawing inspiration from a previous attempt at an invisible sound system that had been abandoned mid-install, Waker decided to install the new speakers high above the seating area in the wooden archways at the top of the pillars. In order to make that happen, Waker and his crew practically had to set up a trapeze act. “They had to go up about three and a half stories to get above the arches,” said Crouse. “Then they had to walk down a wooden catwalk that’s about five feet wide, cut sections out of the catwalk, and build small platforms with Unistrut and threaded rod that went down about eight or 10 feet. Then they climbed down an aluminum ladder in a fall-arrest harness in order to get down onto the platform, and that’s how they would get to the speaker location to aim the speakers.”

To provide coverage for the entire room, Waker set up 12 distinct speaker zones. “The pillars are placed equidistant on either side of the room, so there’s the same amount of space between the wall and the pillar, and then an even amount of space in between the pillars,” explained Waker. “So a 60° or 70° box would have fit horizontally, given the dispersion pattern. The problem was that, to get the right dispersion, the box needed to be angled. You’d have to fire straight down the pillar in order to cover those poor people who are stuck behind the pillars. We divided the chapel up into 12 segments, six on the left, six on the right, and a speaker was dedicated to each of those 12 segments.”

However, Waker could not rely on any old speaker for this particular application. “The problem was, if we used a conventional 70° box, at the back end of each of those 12 segments, or 20 feet away from the speaker approaching the next pillar, you’d end up with a much wider pattern, because that’s just math,” explained Waker. “My grave concern was that this much wider pattern in the back would result in too much splash off the wood-panel walls, which would spill into the coverage in the other zones. But then I got wind of Martin Audio’s CDD Series, and that was the only speaker that I could find that could do what we needed it to do, because the dispersion pattern is very wide below the speaker and much narrower as you move away from it.”

All of the 12 zones feature one Martin Audio CDD12. “Each of the CDD12s is driven by one channel of a Martin Audio MA 2.8Q amplifier, and each has its own processing channel from the Martin Audio DX0.5,” explained Waker. “The DX0.5 is a natural fit, because it’s loaded with presets and it’s designed for the installation market. We put four of those in there. One of them actually does nothing but distribution. We just took a stereo feed into it from the console, and it provides six outputs, which go into the next three stereo processors to give us the zone processing.” Three MA 2.8Q amplifiers drive the 12 speakers. “We took care to orient the speakers correctly,” Waker elaborated. “They’re all flown at about 32° up from horizontal. And there are big light fixtures hanging from the ceiling that weren’t going to go anywhere, but we managed to squeak by those.”

The speaker location required some custom fabrication to make everything possible. “We fabricated custom brackets to mount the speakers,” said Waker, “and [North Andover MA-based contractor] Buddy Electric custom-built cradles, which are suspended under the catwalk. Then we positioned the speakers using an inclinometer to crank it up and down to exactly the right angle.” Waker continued, “Every speaker is a home run. We ended up with 5250 feet of speaker cable on the project, so just 30 feet short of a mile!”

A few additional fill speakers for faculty seating, stage monitoring and under-balcony coverage round out the sound system. “The only visible speakers in the room are four Martin Audio CDD8s,” said Waker. “Two of the CDD8s are aimed at providing outfill at both left and right of the stage for the faculty, who have a habit of congregating on either side of the stage. And then there are two others that are angled inwards to provide onstage monitoring for the performers.” Nine 70-volt Martin Audio C4.8T ceiling speakers are located under the balcony; these are driven by an Ashly NX1.54 amplifier. “All of the visible speakers were custom painted to blend in by John Sirois, an independent master woodworker who works on restorations of historic buildings,” added Waker.

The space’s two preexisting Yamaha 01V digital mixers were kept in place for the new system. Other preexisting components include several microphones by Shure, Countryman, Audix and Audio-Technica, as well as a pair of Bose 101s used as backstage monitors.

The audio upgrade has been well received by Phillips Academy faculty, students and AV personnel. The system was immediately put to the test in a high-profile speaking engagement, and it passed with flying colors. “The first big event we had on campus after it was installed was Jane Goodall’s speech,” recalled Crouse. “It sounded spectacular. The audio was clear everywhere, and it was an absolutely packed house. The system worked beautifully, everybody could hear her, and aesthetically, everyone just walked into a beautiful-looking chapel.” He added, “That’s one of the best things about this install; the space looks like a chapel again. It looks how it was when it was originally built, because all the technology is hidden.”

Equipment List

1          Ashly nx1.54 4 channel amp (drives 9 C4.8T under balcony speakers 70V)

Audio Technical mics*

Audix podium mics*

2          Bose 101 monitor speakers* (backstage)

JL Cooper midi bridge* (Yamaha sync)

9          Martin Audio C4.8T ceiling speakers (under balcony)

3          Martin Audio MA2 4-channel amps (drives 12 CDD12 speakers)

12        Martin Audio CDD12 co-axial speakers

1          Martin Audio MA 2.8Q 4-channel amp (drives 4 CDD8 speakers)

4          Martin Audio CDD8 coaxial speakers

4          Martin Audio DX0.5 speaker management systems

1          QSC CX204V 4 channel amp*

Sennheiser mics

4          Shure ULX1 G# bodypack*

4          Shure ULX-S24/Beta 58-G3*

4          Shure WL 184 lavalier mics*

Shure podium mics*

2          Yamaha O1v 96 digital mixer*

Speaker cable 12 AWG 99.9999%* (4500”)

Speaker cable 14/4 AWG 99.9999%* (750’)

* = owner-furnished equipment

List is edited from information supplied by Balanced Input.

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