JBL VERTEC at Robsham Theatre, Boston College

	Photo credit: Adam Shulman

The Robsham Theatre Arts Center (RTAC) is a focal point of Boston College in Massachusetts, USA. Built in 1981, the facility houses the 591-seat Robsham Theatre, along with an exhibit space, a studio theatre and other facilities. As the Robsham Theatre's presentations grew in scope over the years to encompass musicals, dance programs, drama, and theatre productions, it became clear that a redesign of the original audio system was needed.

The Robsham Theatre system is one of the first to use JBL VERTEC VT4886 subcompact line array elements, with 12 VT4886 loudspeakers forming a single, center array supplemented by two JBL VPSB7118DP 18" powered subwoofers suspended directly behind the array, with six additional AC15 speakers along the lip of the stage. The system is driven with Crown Audio I-Tech HD amplifiers and BSS Audio Soundweb processing. System management is handled via the Harman HiQnet System Architect communication protocol and software for remote control and monitoring.

SIA Acoustics, of New York, served as the system design consultant, with Boston Light and Sound performing the installation. "The project started because the original sound system had become outdated," says Adam Shulman of SIA. "However, after looking at the venue and its current and future needs, we realized there were some additional requirements -- the project needed to encompass not only the PA but the media infrastructure as well. The RTAC is also a teaching facility, so it is critical that the students are able to access and use the equipment in a way that's reflective of how things are done in the real world. As a result, the theater's patchbays, racks and cabling were also substantially overhauled."

"The system needed to provide even coverage, support the spoken word very well and provide moderate to high SPL for more dynamic productions," says George Cooke, of the Robsham Theater Arts Center. "I suggested going with a line array system because it would perform well in the space, and give students the opportunity to work with an industry-standard loudspeaker configuration."

Shulman continues, "We looked at the JBL VT4886 and found a number of compelling features that made it very suitable for this project. The product performs as well off-axis as well as it does on-axis -- often, loudspeakers will be fine on-axis but compromise off-axis performance. And vertical dispersion is where the rubber meets the road. If a single element performs badly in this regard, the issue is severely compounded when you stack the elements in a line array. Throw, consistency, coverage -- all of these commonly used metrics are the result of directivity. Many speakers fall apart off-axis, horizontally or vertically [especially important in vertical arrays]. The VT4886 combines good off-axis response, compact size and proportionally high output, and these were the primary factors in selecting it here."

The VT4886 loudspeakers were placed in an unusual configuration -- the main loudspeaker system encompasses 12 VT4886 loudspeakers in a single line array above the stage. "As it turned out, the excellent horizontal coverage of the VT4886 loudspeakers enabled us to place them in a single 12-box array exterior to the catwalk area," Cooke notes. "Although most installations would place arrays on both sides of the stage, we ran an acoustical analysis and determined that a mono cluster would work wonderfully in the Robsham Theater. This is unusual, but we didn't need a stereo image, and we get real 120-degree coverage out of the VT4886 loudspeakers." Shulman points out, "Both intuition and the predictive data indicated that a single array of greater length would outperform two shorter arrays. Given a finite budget, the need for a consistent experience [which benefits the entire audience] outweighs the argument for something like stereo imaging [which only a small slice of the audience typically enjoys]. We were confident this was the right choice and the results have proven it to be the case."

"The subsequent real-time measurements exactly matched Shulman's predictions," Cooke said. "There are no 'choice seats' anymore because now it sounds great wherever you sit."