At times, designing sound for performing-arts venues can be a rather static process. That is, a designer maps out a system to meet a variety of performance types and styles while also fitting within the scope and limitations of the venue, and that's pretty much that.

However, an ongoing sound design at Pittsburgh's Benedum Center deviates from this mold. Christopher M. Evans, house sound engineer at the Center for more than a decade, has taken a somewhat different approach so that the system can be significantly altered and tailored to better match the specific needs of each production.

The Benedum Center, home of the Pittsburgh Opera, Ballet Theatre, Civic Light Opera, and Dance Council, hosts more than 225 shows annually. Christened the Stanley Theatre when opened in 1928, the 2,800+-seat venue, located in the heart of Pittsburgh's downtown cultural district, was restored to its original splendor in the early 80s. Over the past few years, Evans has taken an evolutionary process in replacing the sound system installed at that time, carefully refining it so that it is capable of adapting to an ever-expanding roster that includes touring Broadway productions and concerts.

"What we've developed, and continue to shape, is a system that's never really permanently installed in the traditional sense. Rather, it expands and contracts to best meet specific needs," explains Evans, who provides the mix for every performance in the hall except Broadway touring productions. "There is no set configuration. We adapt things from our own inventory, providing as much or as little as is needed."

While only a single loudspeaker cluster is currently in place--at the apex of the stage proscenium--it can be augmented significantly. Loudspeakers can be positioned on each side of the stage, with surround speakers able to be positioned behind the audience and fill speakers deployed in a number of configurations.

Eventually, the goal is left-center-right loudspeakers above the proscenium to provide main coverage in the majority of situations without eliminating any of the other options or potential enhancements. One specific direction is the implementation of 5.1 surround, or at the very least, a modified version of this concept.

A digital matrix in development with Midas has proven highly useful in this pursuit. Currently called Tasmin, it's an 18-input, 16-output device with equalization and delay on each output. Not only does it afford implementation of 5.1 and other surround scenarios, but it's also a highly useful tool for storing and recalling "scenes" from previous shows.

"We have exceptional flexibility with Tasmin, where any input can feed any output, with individual processing for each," Evans notes. "In addition, it's really helped us eliminate some of the repetitive processes. System parameters for any performance can be saved and accessed, whether they're for a regularly performing tenant like the Ballet, or a concert act that only visits every two years. So while we might be busy physically configuring the loudspeakers for an individual performance, the key routing and processing for that configuration and performance is already done."

House mix is handled on a Midas XL4 console, while the processing picture is fleshed out further with TC Electronic 1128 computer-controlled equalizers, soon to be replaced by Rane 228 equalizers. Also capable of being digitally controlled via PC, the analog 228s will be primarily used for foldback on the stage and sound effects.

A Crest CKS Series amplification package featuring NexSys computer control accessed on a PC at the mix position, already implemented, also plays into the flexibility and convenience picture. "Again, I can save and recall settings. At the same time, NexSys provides full load monitoring capability as well as general peace of mind as to how the amplifiers--located remotely in a backstage room--are performing, and if there are any problems," he notes.

Sonically, Evans' goals for the system are maintaining an already high level of vocal intelligibility, ideal for the needs of theatrical productions, while at the same time continuing to up its full bandwidth capabilities. The target is 15dB-20dB of dynamic headroom, but with exceptional pattern control.

Selection of the right loudspeaker components is crucial to making this happen. While evaluation of likely candidates continues, Evans concedes he's got the field narrowed to a couple of options.

"In order to get excellent pattern control across most of the bandwidth of a loudspeaker, you need to have either a large horn or some sort of a modified line array, combined with a dipolar array on the low-frequency section," he says. "Right now, I'm leaning toward the large horn approach for the main cluster, with a dipolar low end."

While the dipolar concept dates back to the landmark research of Harry Olsen, it's lately been revived and updated by electro-acoustic consultant Craig Janssen, applied in numerous leading-edge performing arts sound designs. At its essence, the dipolar concept overcomes the problems of excessive off-axis, low-frequency projection along with minimizing undesirable lobing effects. In other words, low-frequency energy is more tightly controlled and focused, and in particular is kept off the stage, maximizing gain before feedback from stage microphones.

The theatre's acoustic design, under the direction of the late Ted Schultz, a noted acoustician, is fairly successful in accommodating the diverse performance agenda, Evans says. One aspect of note is an acoustic shell at the proscenium, enhancing the coupling of the stage house/orchestra pit with the room, and vice versa.

It might be said that the sound reinforcement system is a natural extension of this coupling process, a marriage of modern technology with a grand, historic space hosting ever-increasing variants of performance both old and new.

"The bottom line is that we're doing everything possible to handle anything that comes through the door," Evans concludes. "The difference is that it's being done in a way that allows assembly of individual yet cohesive components which form effective systems that can then be further customized. You could call this approach 'tailoring for the specific,' rather than using something fixed that has to be adapted as best as possible."