NORTHRIDGE, California – Alliance Redwoods Conference Grounds is a Christian retreat, conference center and summer camp located in the northern California’s Sonoma County redwoods. Since 1946 they have been providing families, churches and schools with recreational camp and other activities. Alliance Redwoods Conference Grounds has recently undergone major renovations to its facilities, including revamping a gymnasium to double as a music venue with the installation of a unique, custom JBL VERTECA® line array system that can be quickly set up and removed as needed.
“In recent years Alliance Redwoods has been upgrading the camp’s technology and infrastructure to revitalize it almost beyond recognition,”? said Greg Adams of Sound Expressions, systems integrators in Santa Rosa, California. “A need had arisen to create a larger music venue, and management decided the existing gymnasium should be adapted to create a functional live music space.”?
Nevertheless, the gymnasium presented some major hurdles. “First of all, it still had to be able to be used as a gym—we couldn’t just gut it and build a dedicated music venue,”? noted Adams. “Also, most people think of gyms as spaces with bad acoustics, and this one absolutely fit the stereotype. It was an echo chamber, a 100-percent unusable space for music as it originally stood.”?
Sound Expressions brought in Rocky Giannetta of Perform Acoustics, a Roseville, California acoustical consultant and manufacturer, to do an acoustical study that included creating a number of EASE (Enhanced Acoustic Simulator for Engineers) models of the space. “Based on the models and Perform Acoustics’ recommendations for using their room treatment products, we determined we could tame the echo and make the space work.”?
Sound Expressions then used the JBL VERTEC Line Array Calculator II speaker configuration and acoustic modeling software to determine what loudspeakers would work best, and where they should be placed. They specified two line array clusters, each containing four JBL VERTEC VT4886 subcompact line array elements, complemented by two SRX728S subwoofers and four JBL MRX512M stage monitors. However, the actual installation required Adams to come up with a novel solution.
“Because of structural and space limitations and the fact that the room had to be dual-purpose, we had to be able to move all the A/V and lighting out of the way when not in use—not just the VERTEC line arrays, subs and stage monitors, but also the video projector and LED lighting towers,”? Adams pointed out. “We could not permanently mount anything.”?
Adams and his team designed a custom truss that moves up and down using motorized chain hoists. The VT4886 loudspeakers, LED lighting system and video projector are permanently mounted on the truss. When not in use, the truss disassembles into three 10-foot pieces that drop into rollaway carts for easier storage.
The cables to connect the speakers, lighting and projector are permanently installed along wooden trusses in the ceiling. The VT4886 line array loudspeakers and SRX728S subwoofers are powered by Crown I-T12000HD and I-T9000HD amplifiers, respectively, and the MRX512M monitors are driven by Crown XTi 2000 amps.
“With the Crown I-Tech HDs we got rock solid clean power and the most comprehensive DSP available in an amplifier. Crown is optimized to work with JBL VERTEC and when we tuned the PA all the equalization was done in the amplifier DSP. Also, since we have so many users on this system the ability to electronically lock the amplifier settings turned out to be a very valuable feature,”? added Adams.
The SRX728S subwoofers have casters that enable them to slide into cutouts on a movable stage that can be set up on the floor. Once the stage is in place, the MRX512M monitors are put into position.
The audio system is operated by a Soundcraft GB8 32-input mixing console, which is installed in a custom-built, wheeled, moveable, front of house mixing cart. The cart houses a snake that runs from the mixer to a custom-made quick-disconnect mass connector in a recessed floor pocket at the FOH position. There’s another mass connector at the stage position for which to plug in the snake box. The appropriate wiring makes it to the amp rack, which is permanently mounted in an adjacent room. “They had to cut a lot of concrete to make that work,”? noted Adams, “but it was the only way we could make the system portable and removable, while accommodating all the connections for microphones, amps, contact closure and power sequencing.”?
“The Alliance Redwoods staff did most of the work, under our supervision. They placed and angled the speakers according to the JBL Line Array Calculator II results, and we ran our system calibrations using SMAART. The predictions of the Line Array Calculator II software turned out to be extremely accurate. We’re very pleased with how such an unconventional sound reinforcement installation turned out so well.”?
For more information about Sound Expressions, please contact
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