A/V at A.V.H.S.

Mar 1, 2002 12:00 PM, By Keith Clark

The Apple Valley High School Eagles are a bright and enthusiastic lot as a rule. They enjoy a diverse academic experience that includes many cocurricular activities. Case in point: Rehearsals for this year's musical production, The Sound of Music, are hot underway. The production brings together the theater, choral and instrumental music departments for a gala production. Sets are built and lights are run by students assisted by school faculty. And this year, a new performance theater featuring a dramatically improved sound reinforcement system is likely to lead to more awards for the student stars.

The theater, busy virtually every day of the school year with performances and rehearsals, hosts three big dramatic/musical productions each year, plus choral concerts and festivals, numerous band concerts and more. The excellence of the programming at this 2100-student Minnesota high school is confirmed by its third consecutive selection as a Grammy Signature School, a national honor.

Kingdom Sound & Lighting, in nearby Burnsville, is one of the leading contracting firms in the greater Minneapolis-St. Paul area. The KSL team recently completed work on phase one of an upgrade to the school's sound reinforcement system, including new house loudspeakers, digital signal processing and amplification. Additional phases, such as the installation of a new house console, are expected to be addressed over the next two years.

Gary Johnson, who frequently collaborates with the contracting firm on higher-end projects, provided the system design, working closely with Loren Bartelt, head of Kingdom Sound. In addition, Chris Moen, a freelance sound engineer who assists in supervising the systems at the theater, offered invaluable information and support to the sound team.

WHERE THE MAGIC HAPPENS

The theater is about three times wider than it is deep (approximately 120 by 40 feet), with a capacity of 860 seats fanning outward from the stage, gently rising to the curved back wall. Acoustics are good according to the sound team, with acoustical clouds forming dual concentric rings above the stage, extending out over a portion of the audience area. All seats are padded, and the aisles are carpeted.

“The choral people [are] concerned that the room may be just a bit too dry from an acoustical standpoint, so future plans call for livening it up electronically,” sound designer Johnson notes. “We've done some preliminary work in this regard, focusing on the future placement of six loudspeakers — three per side — along a ceiling ridge toward the rear of the room. In fact, cabling has already been put into place in the front-of-house loudspeaker patch panel that will allow access and signal routing to these loudspeakers once they're installed.

“This subsystem will be available for providing specific effects to enhance theatrical productions and for adding a general fullness of sound to the room. Processing, including delay, will also be a part of this effort,” he adds.

Given the extreme width of the room, a left-center-right loudspeaker arrangement was used to of- fer the best possible coverage, in addition to increased spatial imaging. Using modeling tools, including AcoustaQWIK and EASE, the focus became a center array dedicated to providing point-source vocal coverage throughout the entire room, with left and right arrays providing stereo music.

“This space is great for the sense of intimacy it provides in relation to the stage,” Johnson says. “Most theaters are deeper than they are wide, and you lose that intimacy. The challenge, however, comes in devising a system that fits and works optimally within a much wider coverage area.”

The previous system, in place for more than a decade, had become outdated and needed replacement. This project afforded a great opportunity to address problems of uneven coverage and comb filtering. As they do on many higher-end projects, Kingdom Sound & Lighting selected Renkus Heinz loudspeakers, preferring their natural, uncolored sonic signature, particularly the smooth-yet-present high-frequency characteristic and tight, accurate, predictable pattern control.

FLYING THE EAGLES' SPEAKERS

Single rh ce153/12 three-way full-range loudspeakers (with passive mid/high) were deemed an optimum solution based on the modeling. These speakers are flown left and right above the front portion of the stage at about 18 feet from the floor and 60 feet apart. Modeling also helped determine the optimum, gently downward-facing angle for these two loudspeakers anchored into place by ATM Fly-Ware eyebolt/aircraft cabling hardware.

The CE153/12 was designed specifically for wide but shallow rooms, like theaters. It provides wide-angle 120° horizontal coverage, as well as asymmetrical 50° vertical coverage (+20°/-30°) that helps direct more sound to the audience and off the reflective ceiling surfaces. CE153/12s also include Renkus Heinz's proprietary CoEntrant Waveguide Technology, which offers a truer point-source performance, as well as natural alignment and controlled dispersion.

Feeds to all main loudspeakers are assigned from the subgroups of the existing Soundcraft Delta Series house console (slated for replacement in the next phase of the project). Stereo music programming routed to the pair of CE153/12s includes portions of both left and right mix.

“We set it up so that you get parts of both mixes in each speaker,” Johnson explains. “For the most part, of course, programming is dominant with respect to traditional routing — left speaker gets more left channel info, and same with right — but mixing it together supplies better overall imaging. A bit of this effect is lost as you move more toward the far corners of the coverage area, but this is inevitable. You can't completely fight proximity issues.”

The center array is made up of four Renkus Heinz TRAP40MH/7 mid/high modules, positioned about 5 feet forward of the line between the left/right loudspeakers in deference to a video screen that occupies this location. These loudspeakers are arranged in a single-level horizontal array, with each loudspeaker aimed to cover its respective seating section. Transitioning between cabinets occurs in the aisles.

“It's great to keep the vocals tight in the center channel and then spread the music mix between left and right,” says Moen. “There's great stereo imaging, particularly with these speakers.” TRAP 40MH/7 mid/high modules also have a CoEntrant design that bolsters point-source characteristics, with a 40° horizontal coverage pattern and asymmetrical 75° (+30°/-45°) tightening focus of energy on the coverage area. True Array Principle (TRAP), another proprietary Renkus Heinz technology, helps place the acoustic centers of each loudspeaker in near-perfect alignment when used in arrays.

Unlike the left/right loudspeakers, the center array loudspeakers have no downward tilt. Modeling helped ascertain this optimum positioning. Acoustical foam was attached to the underside of the concentric panel above this array, further helping to eliminate early reflections. Also flown with 12-point Renkus Heinz TC4-RHANG hardware, the center array is painted to blend in beautifully with the wood of the concentric circles as well as that of the room walls.

“The RH TRAP arrangement is virtually seamless and quite remarkable, particularly in the vocal range,” Bartelt says. “The look of these particular loudspeakers for this project is great as well, and that's one of the things the client rates highly. We've had a lot of positive comments about it.”

The mid/high loudspeakers are accompanied by dual Electro-Voice TL12 low-frequency loudspeakers, selected based on the sound team's experience with them and on budgetary constraints. These are horizontally stacked and flown above the TRAP array and concentric circle surface.

THEATER SUBTLETIES

The unique shape and configuration of the room presented a challenge with respect to subwoofer location. After considering a number of options and evaluating them with modeling, the sound team chose two compact Acoustic SBT 2.6 subs mounted at the ceiling level, one per side. Positioned sideways and held firmly in place with custom steel frames designed by Kingdom Sound & Lighting, these project into angled concrete soffits that both diffuse and distribute energy evenly throughout the room.

“There were a number of challenges on the installation side of this project, particularly with respect to flying all of these loudspeakers in their optimal positions within an existing structure,” Bartelt notes. “First, given the heavy use of the room, it was tough finding enough concentrated time to get in and do the job. We were able to arrange a 3-day period to do the whole thing. Suffice to say there were no 8-hour days.

“New cabling was run down the ceiling catwalks, and getting around the acoustical clouds was complicated. You can't walk on these structures, so lifts and scaffolds were positioned between and around them, as close as possible,” he continues. “The subs were especially tough, getting them way up there, secured in the framework, and then properly cabled and connected.”

A FLEDGLING FLIGHT

this project also marked one of the first applications of QSC's new 2-channel DSP-3 programmable digital signal processor modules, which attach to the rear 2-channel data ports of the four new QSC CX-Series amplifiers driving the new house loudspeakers. (Two existing JBL amps were retained to drive stage monitors, and all amps are rackmounted in the sound booth.)

Using his laptop outfitted with the DSP-3 software package linked to the modules via RS-232 ports, Johnson established all system processing, including parametric equalization, crossover filtering, compression and limiting. Johnson notes that one feature that worked really well was the ability to add delay to enhance the voices of actors and performers. All of the optimized settings are password-protected to prevent tampering; and for added protection, the existing software used to do the programming must be used to make any changes. No other version will provide this access.

“This DSP product is pretty incredible and a really good value,” Johnson says. “It has two channels of DSP that allow you to build blocks of whatever you need in terms of EQ, crossover, etc. This is the product that we, as sound contractors, long dreamed of. You don't have to wire a bunch of signal processors, but you can go right from the house console into the processor and then into the amp. These units are also clean-sounding and quiet.”

A Rane ME-60 dual 30-band graphic equalizer is inserted to allow tailoring of the stereo music mix, and, as previously mentioned, the existing Soundcraft console is still in place, with its subgroups providing both LCR and sub feeds. It's not ideal, but it works for now and will suffice until a suitable replacement can be made, preferably one with true LCR panning capability.

NEXT STEPS

while the new console issue is yet to be finalized, Bartelt notes that another goal is to move the mix position into the house, getting it out of the enclosed booth. Not only is it tough to accurately hear the system while mixing, but also the cramped confines of the booth necessitate positioning the console sideways rather than facing the stage.

“Ideally, we'd like to build the new position where the console could be rolled out from the center of the back wall into the audience,” he explains. “[It] would dramatically improve the situation. Especially with LCR, it would be a great central vantage point to get a feel for what the system is doing.”

Right out of the gate, the new system proved up to matching the school's expectations when used with an original production based on 2001: A Space Odyssey. The show featured a full band, singers and choruses, and recorded tracks joining video and lighting elements.

“The imaging opened things up beautifully, accompanied by a low end that literally shook the seats,” Johnson says. “The production values were impressive at any level, and especially for a high school. And with Chris [Moen] leading the audio effort, it's really coming together.”

“The room already presented an incredible opportunity in terms of a live sound environment,” Moen concludes. “This system, matched so well with its environment, has an impact that's almost mind-boggling.”

Keith Clark is an independent writer for the pro sound industry and has authored hundreds of system application articles.

Learning to Fly

Straightforward System Design Allows For a Learning Opportunity

Chris Moen, the freelance engineer who supervises the theater's systems says, “We allow and encourage students to work the sound system, with appropriate supervision, of course. This is a learning opportunity that's rare. They won't learn if I do it all, and that's not the point. Students should have the chance to learn about systems, learn about mixing. I just show them the basics and let them proceed from there.”