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Installs
January 2005
Highland Presbyterian Church- Dallas, TX
By Daniel Keller
As any audio professional will tell you, church audio has its own set of rules. While many of the basics of system design are no different than traditional concert sound, creating a sound reinforcement scenario for houses of worship is a challenge that requires a whole additional set of skills. Many a sanctuary has been plagued by the results of system designers who, while they may be perfectly competent to create a more traditional presentation system, are relatively clue-free when it comes to churches' special requirements.
For one thing, there's the need to design a system that is equally effective in delivering intelligibility and musicality. Falling short in either area will leave your congregation languishing somewhere between uninformed and uninspired.
Another factor all too often overlooked is that of designing a system that fits the room not just sonically, but visually. In far too many sanctuaries, the size, design or positioning of the speaker system ends up calling attention to itself like a Hawaiian shirt matched up with a pair of plaid pants.
Tradition Rules
The need for aesthetics is that much more pronounced when dealing with a classic structure. Preserving all that is revered by architectural and traditionalist standards makes for a complex set of challenges where, in an ideal world, the system will be unseen and fantastic sound will simply come out of nowhere.
Such was the circumstance at Highland Park Presbyterian, one of the oldest churches in Texas, and housed in certainly one of the area's most breathtaking buildings. Originally established in 1926 as a neighborhood church with some 190 members, the church has a long history of being a driving force in the Dallas area and well beyond its borders.
The original congregation met on the second floor of the nearby Alexander Hall, under the leadership of Dr. W. A. Alexander. In the early 1940's Dr. William Elliott arrived from Atlanta, GA to begin a 29-year pastorate and preside over the church's evolution into one of the denomination's largest congregations.
A highlight of Dr. Alexander and Elliott's legacies was the construction of the building which, while having undergone some changes over the years, has been the church's home for well over half a century. The cruciform-shaped structure boasts a massive traditional pipe organ, intricately appointed 65-foot vaulted ceilings, and ornate stained glass throughout. While breathtaking to behold, it represents a potential sonic nightmare, as the room's acoustical design lends itself well to choir and pipe organ but wreaks havoc with speech intelligibility.
"Despite the room's size, it was surprisingly dead, acoustically speaking," recalls John Eldridge, the Church's Technical Advisor for Mass Media. "The ceiling has the appearance of wood, but is actually lathe and plaster covered with a horsehair-based material that was popular at the time. The walls were also covered with an absorbent material, making for very little reflectivity."
While this anechoic character may be an ideal scenario for a more contemporary venue, it's far from desirable for a traditional live choir and organ service. Hence, when the Church was ready to replace the aging pipe organ in the mid-1980's, the decision was made to take steps toward livening up the acoustics as well.
Unfortunately, what works well for music is not necessarily the best option for speech intelligibility, and while the musicality of the room was significantly improved, comments from parishoners struggling to understand the sermons were on the rise, along with requests for assisted-hearing systems.
Finding a Balance
A number of solutions were attempted over the course of more than a decade, and while there was at least some improvement, the intelligibility factor continued to be somewhat elusive. Experiments with concealing speakers within the chandeliers, while visually favorable, were only marginally successful. When one of the church's more prominent members expressed frustration at a presentation by his own daughter being all but lost in resonance, it was clear another course of action was needed.
"It was quite a challenge to try and keep the speakers hidden while providing adequate coverage," recalls Robert Rose, Senior Consultant for Acoustic Dimensions. The respected Dallas-based firm's reputation for problem solving and their extensive experience in the particulars of church audio and acoustics made them the logical choice for the job. "One of the biggest issues was the location of pulpit and lectern, which were very far out in front of where the main speakers had been positioned, giving them very little opportunity for sufficient gain before feedback."
At the client's request, Rose and company brought in a DSA (Digitally Steerable Array) system, made by Eastern Acoustic Works. "They had heard a number of good things about the DSA, and Mr. Eldridge in particular felt it might be the solution they were looking for," Rose explains. But though the church were impressed with the DSA's performance, it wasn't quite what was needed to address their particular sonic conundrum. "While it provided more than adequate vertical coverage, the horizontal coverage was almost too efficient for the room, which is relatively narrow. There was a bit too much energy coming back off the side walls. So we went back to our bag of tricks, and looked at similar spaces we'd worked with in the past."
One of those spaces was the famed Washington National Cathedral in Washington, D.C., for which the company had provided audio design in late 2002. The Cathedral was another space which called for a system with very tight focus, and Acoustic Dimensions collaborated with EAW's Kenton Forsythe to develop a speaker that exhibited control in the horizontal and vertical planes, while sounding more like a hi-fi system than a P.A. "The basic premise was that we were limited to a space of only 16.5 inches wide, and we spent a lot of time figuring out how to get the best pattern control out of that sixteen inches," Rose recalls.
The result was a customized system based around EAW's CC366 drivers. "The CC366 is a very interesting design," Rose continues. "It's got six high-frequency domed tweeters, each on a small waveguide, twelve 3.5-inch midrange drivers, and six 6-inch woofers, providing for an extremely tight horizontal and vertical pattern control. It borrows a lot of concepts from the KF730 and KF761 series line arrays in terms of geometry. It's a very tight focus, much like shining a flashlight on an area. We really couldn't have found a better solution for this room, both sonically and visually."
To augment the CC366, Rose prescribed a pair of EAW LS432 column arrays for the last 4-6 rows. "We were limited in the amount of coverage we could achieve with only three boxes in front, and that's all we had space for. We also wanted to avoid projecting too much energy onto the rear wall." For aesthetic reasons, the church chose to "test drive" the system without these speakers. While not optimum, there is still a significant increase in intelligibility in these seats, so the church has chosen to delay installing this portion of the system. Additional pairs of LS432's cover the main floor transepts and balcony seats.
The 70V distributed system is driven by a QSC CX302V amplifier, with a four-channel QSC CX404 covering the ancillary low-impedance speakers. A Symetrix Symnet 8X8 processor handles speaker delays within the room, "Originally, we would get a horrendous slap from the walls facing the transepts," Eldridge explains. "By carefully timing the front linear arrays we were able to completely eliminate that bounce."
Due to space constraints, it was decided to leave the mix position on the balcony, but the old mixing desk was replaced with a Midas Venice console, which Eldridge describes as "magnificent." The Midas' larger footprint means the mixing desk can no longer hang on the balcony railing, but the church is fortunate to have among its members an experienced woodcarving artisan, who has created a new booth for the mixer. "It looks like it's always been there," Eldridge enthuses.
The new system has only recently been completed, and the church is presently putting the finishing touches on the new system, including some custom designed grille cloths for the speakers. But early reports are nothing short of overwhelmingly positive. As Eldridge explains, "I was asked recently how my supply of ear buds for the assisted listening systems was holding up, and I told them no one even asks for the systems anymore. We've finally got a sound system where everyone can hear."
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