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Expanding Audio Horizons At Redeemer
Lutheran Church

Speech intelligibility or high-quality stereo music? How about both!

The greater emphasis placed on music in modern house of worship services has created a whole new set of challenges for sound system designers and installers.

Providing quality music reinforcement, especially in stereo, is one difficulty. Doing so while also maintaining speech intelligibility is another. And house of worship spaces are generally unfriendly from an acoustic standpoint, with aesthetic concerns often paramount.

On top of everything else, the public (and customer) is more sophisticated and discerning about audio quality. As a result, there's an audio critic lurking around almost every corner.

With more than 35 years of experience in sound and communications contracting, EVCO Sound & Electronics of Spokane, Washington, is a firm familiar with these types of challenges. In a recent project at Redeemer Lutheran Church, also in Spokane, the company took a unique approach.

"We see a lot of churches going to more music, and specifically, modern music, as a regular part of their services," says Chris Bryant, sales engineer for EVCO Sound who headed up the project. "Our position is that we must keep up with these changing needs or be left behind."

Review & Discussion

Built about 10 years ago, Redeemer Lutheran had utilized a voice reinforcement-only sound system for much of its existence. Over the past couple of years, attempts to augment the musical quality of the system had been made, in large part through simple addition of more loudspeakers and amplification. These efforts had proven disappointing.

A new music director joined the church and insisted that a better solution be found. Music, ranging in style from traditional to contemporary electronic, would indeed be taking a leading role.

At this point, EVCO Sound was asked to put together a new design proposal based upon a thorough site review and in-depth discussions with church personnel. Concurrently, Bryant was informed by Armstrong-Boyce Marketing, a regional sales representative firm, about a unique multichannel stereo imaging device.

The layout of Redeemer Lutheran's sanctuary is pie-shaped - much wider than it is deep - with a floor that rakes up gently from front to back. Seating capacity is about 300. At its apex, the ceiling reaches a height of 22 ft., tapering down to 17 ft. at the side walls.

Bryant notes that acoustically, the sanctuary is "a very usable room," with some acoustic treatment (diffusers) on larger wall spaces. The pews have padded backs, and all aisles are carpeted.

LCR In Stereo

"The customer wanted a stereo system, if possible, and we concurred," Bryant says. "We hadn't done one before, due largely to concerns about the need to provide speech from a central point. It's difficult to develop a simple, cost-effective system that does both."

EVCO Sound proposed a system with loudspeakers configured left, center, and right, with a Miles Technology MTI-3 processor at the heart. Essentially, the MTI-3 provides three-channel stereo sound from a standard stereo input, a concept that interested both the designer and the customer. The cost-effective device comes in a compact one-rack-unit package.

The MTI-3 combines left and right input signals, via a patent-pending matrix, to create left, center, and right output signals. The process results in a true stereo image throughout the entire listening area. Any signal components panned fully left or right will appear in the corresponding loudspeaker at full level, and in the other two loudspeakers at 6dB down with appropriate phase and polarity. No matter where listeners might be located (in the listening area), they are receiving a mix of left and right.

"A major concern with standard stereo is that people on one side of the sanctuary or the other only receive signal from the loudspeakers on their side," Bryant says. "Those on the left side receive sound only from the left side of the system, and the same goes with the right side. The MTI-3 eliminates this drawback."

Also via the matrix, center-panned sources in the mix, like lead vocals or kick drum, are focused more in the center channel. The MTI-3's analog process does not dynamically modify the signal, and it provides the maximum theoretical 6dB of separation between any two of three output channels.

A 32-channel Allen & Heath GL3 mixing console feeds the MTI-3, which is rack-mounted with other processing equipment at the mix position. Bryant notes that the GL3 was selected for its flexibility, offering six selectable auxiliary busses and four group outputs.

The GL3 is fed by eight microphone jacks mounted in a custom panel located to one side of the pulpit area. This panel also includes four monitor outputs. Another panel offers 24 inputs - for the band - also linked to the GL3. The panel also includes parallel connections for monitor outlets.

Discrete Center

Three Shure wireless microphone systems, used by the pastor and other people speaking during services, are also fed to the console. The receivers for these systems are mounted in their own case and located at the mix position.

The GL3's left and right outputs are fed to the MTI-3's left and right inputs. In turn, the MTI-3 provides the left/center/right mix that is distributed to the loudspeaker system. All three channels of the main house feed include parametric equalization, courtesy of Rane PE17s, with compression/limiting on each output provided by Symmetrix SX208s.

Also of note: the wireless microphone systems are routed, via one of the console's group outputs, to the MTI-3's discrete center input that feeds only the center loudspeakers. This feature ensures "point-source" vocal clarity and focus. A third-octave equalizer is patched into the group insert so each wireless mic system can be equalized separately.

The system's amplifiers, Altec Lansing Anniversary Series, are located in an mezzanine-level room that helped keep cabling runs as short as possible. A remote sequential switcher allows them to be turned on/off from the mix position. Two Altec Model 9442 amplifiers drive the main loudspeaker system, while a Model 9444A drives the subwoofer.

Wider Dispersion

Selection of the house loudspeakers came after live evaluation of several models. The primary criteria was to use loudspeakers that sounded the best for this application while also fitting the budget.

"We selected EAW KF300iPE," Bryant says. "They're a selectable passive or active loudspeaker that sound very good. We are currently running them in passive mode, without their companion controller, but we may add the controllers later. They also offer a wide dispersion (90 degrees) that let us keep the component count down."

The loudspeakers were suspended on an arching support beam that spans across the front of the sanctuary. They are securely fastened by black iron "U" straps that bolt through the cabinets, with the straps then attached to Omnimount hardware which in turn attaches to the beam.

The single left and right loudspeakers are mounted as close to the side walls as possible, and angled inward about 30 degrees. The two center loudspeakers, about six feet higher due to the beam's arch, are splayed out slightly but arrayed as close together as possible.

An EAW SB150 subwoofer supplies low frequencies. It's mounted at the location previously used for the old system's cluster near the ceiling and concealed by an aesthetic fabric covering. "This location isn't ideal; we would have liked to put the sub with the new central cluster but there just wasn't space," Bryant adds. "However, it's still performed well despite this limitation."

Meeting Many Needs

A TEF Precision EQ analyzer was utilized during system tuning. "This approach worked out very well," Bryant says. "We were able to flatten out the loudspeaker response a bit further. It was already good, but we made it better."

When first activated, the system's performance indicated that the challenges had been met. Full, spacious sound for music is combined with the discrete center speech reinforcement, meeting both needs.

Acknowledging that he was initially a bit unsure of the left/center/right stereo approach presented by the MTI-3, Bryant notes that the new system at Redeemer Lutheran has exceeded expectations. He adds that the unit and system were convenient to implement.

"The MTI-3 was intuitive, and easy, to set up," he says. "You can do a lot with it, to get the effect that you're looking for. It's also nice to be able to pan the image around while still retaining the center presence. Both the channel separation and imaging have resulted in a higher level of sound quality than we would have otherwise been able to achieve."



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