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Dictating The Direction
Factors that can drive a system design
It's no secret that room acoustics and aesthetic considerations play
a central role in determining a sound system design. When it comes to
selecting loudspeaker components, to positioning them properly, as well
as to accurately processing the sound they reproduce, acoustic and architectural
constraints always have a direct influence.
All Pro Sound, based in Pensacola, Florida, recently finished a house
of worship sound system project in which difficult acoustic and design
challenges had to be addressed with somewhat unusual solutions to produce
the desired result. The work at the new 1,800-seat sanctuary of Immanuel
Baptist Church, located in nearby Pace, Florida, required a two-year
partnership between the company and client.
The sanctuary has a complex ceiling configuration, designed by Dallas-based
Acoustic Design Associates, to address critical room acoustics and outside
ambient noise problems, and to shield audio components from view while
making for an aesthetically attractive sanctuary environment. Further,
a 30-foot-high lay-in tile ceiling grid, punctuated by acoustic structures
below designed to resemble clouds, aids in blocking substantial outside
highway traffic noise, creating an aesthetically pleasing environment,
and improving the room's acoustics.
  Views of the sanctuary, including the large screened-in chamber that conceals the loudspeakers. |
"The church staff wanted to be able to control ambient noise, because
in the old facility, services sometimes had to be halted if big trucks
went by on the nearby four-lane highway," explains John Fuqua, All Pro
Sound director of engineering. "The baffling effect created by the ceiling
and the cloud structures helps keep that noise out, while at the same
time, helps focus the sound energy down onto the congregation seating
area."
ADDING TO IT
The single-level sanctuary is extremely wide, with the front platform
measuring more than 60 feet wide and the room and seating “fanning”
out considerably from there. And on top of the complex ceiling construction,
the acoustical consultant also called for a chamber-like structure that
would serve as a façade to shield loudspeakers from view in addition
to saving space on the platform, real estate needed for the church’s
frequent drama productions.
The “hidden from view” rule also applied to the system’s subwoofers,
so they needed to by flown with the full-range loudspeakers within the
same chamber location. As a result, it was critical to insure that low-frequency
energy be kept off of the front platform as much as possible, enhancing
gain before feedback and overall intelligibility of coverage.
"This type of speaker chamber construction is becoming somewhat of a
trend," Fuqua says. "Positioned above the front thrust of the stage,
it basically creates a cleaner look for the sanctuary and if it's positioned
correctly it can work well. It was included for aesthetic reasons initially,
but we interjected our idea that if it was going to be used properly,
the chamber design had to be configured to minimize low frequency resonance.
 A look at the acoustical designs from the front platform. |
"The chamber was designed to be insulated so you don't get any lobing
from the low-frequency output of the subs onto the stage,” he continues.
“We wanted to provide liveliness in the room but not so much that it
came back onto the stage area as reflected energy, which can be detrimental
to monitoring. The subs had to be loaded so the energy was directed
outward instead of in an omni-directional fashion. We typically place
them near the front on the floor or under the stage, but the design
and height of the stage required flying the subs. So very early in the
project we had to take this placement of the subs into consideration."
An “exploded” main loudspeaker cluster, including the subs, became the
focus, to place them as closely as possible to the audience given the
wide surrounding seating configuration. Upon seeing the plans for the
chamber, in addition to the width of the room, Fuqua surmised that specific
loudspeakers would be required, with EASE modeling then deployed to
assist in mapping out coverage, helping to shore up final position and
angle details.
"The specific Turbosound
products that were selected, and which we've used in the past in other
applications, proved capable of providing the intelligibility and coverage
the space demands," he notes. "We knew that, in this project, if we
didn't have the right components we weren't going to get the right results.
Very articulate, very defined coverage with controllability was key
in this project."
All Pro Sound recommended the chamber be insulated to prevent sound
in general, and low frequency energy in particular, from reflecting
down toward the stage area. In addition, the components of the Turbosound
811.3s full-range main loudspeakers are used in a "skeleton" configuration
rather than being housed in a box enclosure.
"The skeleton version is much easier to work with when arraying speakers
in a chamber structure because it allows us to aim the mid-high frequency,
which was critical in this application," he says. One 811.3s skeleton
is included in each of four loudspeaker clusters flown from the ceiling
and encased in the chamber. In addition, each cluster contains one Turbosound
TCS-40 downfill box and one Turbosound TQ425 low/mid box.
Four Turbosound TSW118 subs are situated between the clusters, double-stacked
in two locations and arrayed to provide even low-frequency coverage.
Two Turbosound TCS-56 fill speakers serve as choir fill monitors, and
are flown behind the chamber facing back toward the choir area. All
loudspeakers are driven by QSC
PLX Series amplifiers that include models 3402, 2402 and 1602.
DIGITAL DOMAIN
 The system control position, located at the rear/center of the audience area, anchored by a Yamaha M2500 console. |
A Peavey Architectural Acoustics MediaMatrix X-Frame 88, housed in an adjacent equipment room with the system’s amplifiers, supplies all processing in the digital domain, including crucial delay settings that synchronize the output arrival times of the the various loudspeakers in the cluster. Both MediaMatrix and the Yamaha M2500 48-channel mixing console play important roles in the system, Fuqua says.
"We use digital processing in almost every installation because it
allows us to put whatever components are needed into the mix to create
the sound quality we're looking for. DSP also provides excellent tuning
capabilities for both main and monitor systems.”
The “keep it clean” mantra also applied to the new microphone set. Initially,
four Sennheiser
EW 100 Series wireless mics have been supplied, along with a several
Crown CM700
choir microphones suspended from the ceiling.
"The audio/visual needs and capabilities of the church have grown substantially
from," Fuqua concludes. "The orchestra is growing, drama productions
are expanding and special singing programs are increasing because the
new sound system is able to support the growth. They now have a facility
outfitted with the tools to sufficiently enhance their worship."
