SIA Acoustics Helps Shape the Sound in eTown’s New Performing Arts Facility

FOH Magazine July 2012 Issue
Installations
eTown Hall, Boulder, CO
Written by Sam Berkow
Thursday, 12 July 2012 21:30

The finished stage, as seen during opening sound check.

It starts with a phone call… or an email. “I want to build a studio or a sound stage or even a concert hall.” Usually, it’s the owner, just starting out and wondering how to move forward. Sometimes, it’s an architect or even a construction manager, hired on and wondering how to turn a mostly amorphous vision for a facility into drawings and either a new building or a renovation of an existing space. Some discussion of the project’s program, what the facility’s intended to do, and its space requirements, budget and goals — both operational and initial capital needs, as well as potential cash flow — will quickly reveal how realistic (or unrealistic) the concept is. These calls come often. Sometimes there is a second or even third call. Some of these turn into real projects. It’s all part of the life of an acoustical consulting firm.

Almost five years ago, Nick Forster called my company, SIA Acoustics, sharing the vision that he and his wife Helen had to convert a 17,000 square-foot former church in the middle of downtown Boulder, CO into eTown Hall. Housing eTown, the nonprofit organization behind eTown, the public radio program that has aired since 1991, the facility would include a performance space for the show’s live performances, master classes and interviews. It would also provide a community gathering space while housing the eTown offices and a serious recording facility with a suite of post-production rooms. Clearly, this was a vision they had been developing for some time.

eTown, now broadcast on more than 300 (mostly public) radio stations, has always had the mission to use the power of music for positive social change. Along with music, eTown gives artists an opportunity to discuss their ideas regarding community and current social issues. eTown is now also a fixture on the iTunes store podcast download area.

Getting Started

By the time Nick’s call reached our offices, he was attempting to purchase and permit an old church located just off the town’s main pedestrian mall. The challenge was to address the acoustics of the existing spaces and provide acoustic isolation, while making it all fit into the existing building shell. Additionally, there was a strong desire to be “green,” using as many recycled materials as possible and create an energy efficient space. Of course, it all had to be done on a tight budget of a non-profit organization.

“Helen and I want eTown Hall to be both a great place to create music and a real community center,” Nick said. “After all those years of talking about and learning about environmental issues, we had to make it a really green building — but not just a showplace for the latest gadgets. We want eTown Hall to be the greenest performing arts facility in the country”
Luckily, we started on the right foot. By coincidence, I had met Nick years before, when his acclaimed bluegrass band, Hot Rize, had come to NYC to play a show with John Hartford. Also, I’m a fan of many of the bands featured on eTown, such as Los Lobos, Lyle Lovett and Taj Mahal.

During the first few meetings, on larger projects especially, clients and consultants spend considerable time interviewing each other. This is much more of a two-way process than many would guess. Particularly in the early phases when a design is taking shape, clients and designers spend a lot of time working together. Without good chemistry, that time is less fun and the project is often less successful. The hope is that each side will feel some chemistry, mutual trust and a connection that will allow for productive, honest and focused discussions about the project’s issues.

Before Nick called us, eTown had engaged an architectural firm, Wolf-Lyon, to help with the plans and guide the project through the design and permitting process. This is later than we, as the acoustical designer, would like to get involved. Project architect Jim Walker began by studying the existing building and found it wanting in many areas. “The environmental ethos of eTown dictated that we explore every possible angle to reuse and salvage the existing building and materials within,” Walker recalls. “This posed a challenge, given the condition of the existing facility, with both structural and mechanical systems highly compromised. The building also had nine different floor levels, making for difficult accessibility.” Nick, however, knew that the location and overall layout made the project worthwhile, despite the obvious challenges.

The stone construction of the 87-year-old building was extensively reinforced with steel beams, such as these surrounding the proscenium opening.

Problems and Solutions

Three problems were immediately apparent. In order to expand the existing stage opening and still use the original structural stone wall as the proscenium, the facility would need a new internal steel support structure. Further, the main floor of the main sanctuary and the roof of the performance space were structurally compromised, and would not be capable of supporting the loads required. Lastly, eTown had to raise the money to pay for all of this. To address these issues, the project was split into two phases. Phase one would transform the church’s former offices into eTown’s offices, adding 11 offices, three editing rooms, two dressing rooms, a conference room and a “Green Room” for artist hospitality. Phase two would finish the 200-seat performance space, the studio and a community room, which would be named the “Bohemian” room. “The eTown offices are in a space that is filled with natural light and great energy, making it a comfortable and productive place to work,” adds Helen.

Our role as acoustical consultant is to work with the architect and owner to help them understand the challenges that lay ahead. Nick was clear that eTown needed a full recording studio with a sizable control room and large tracking room. The obvious and only viable choice, based on space, was the old gymnasium of the church. However, this space is located directly behind the stage of the performance space, making the upstage wall common to the stage and the studio. This requires a substantial and costly set of acoustical details to achieve sufficient acoustical isolation to allow simultaneous usage of the stage and the studio.

“We knew that eTown needed a performance space and a studio complex that would be able to operate both separately and simultaneously,” Nick explains. “This required several isolation techniques, including double walls, floating ceiling, resiliently mounted walls, isolated floors and resiliently mounted structural steel to decouple the stage and the upstage wall.”

“SIA Acoustics spearheaded the technical details for the acoustically sensitive components of the project,” adds architect Jim Walker. “We worked together to make sure the details met code, were structurally sound, and provided the best use of space possible. One such challenge was that only a hollow 8-inch concrete block wall separated the stage from the recording studio. This presented a problem where sound and vibration isolation were critical. The clever but challenging solution was to both grout-fill the wall and decouple the stage structurally from the surrounding walls. More than 17 different acoustical conditions, each requiring a specific detail, were required to achieve this decoupling.”

View of the seating area from the round window over the entrance.

To complete the isolation between the stage and the studio, the studio itself was built as a completely isolated box-in-a-box with 6-inch stud construction. With a ceiling more than 18 feet high and a pop-up section of ceiling extending upward to almost 22 feet, the 600-square-foot studio tracking room provides a large cubic volume, allowing the sound to bloom in a tonally balanced manner. Of course, the use of 6-inch studs to support free-standing walls impacts the size of the room. To offset this, a compromise was made. The wall between the control room and studio was reduced, to a relatively thin, double-stud wall construction. This eliminated the possibility of using soffit-mounted loudspeakers but returned at least 100 square feet to the studio.

One interesting way in which the eTown green ethos was used in the acoustical design was the use of the wood from the removed floor. This wood was re-purposed to become a facility-wide acoustical diffuser at the upper rear wall of the performance space. Designed by SIA and Jim Walker, this element will be an effective acoustical diffuser. It also is in line with the reused materials approach, and it looks extremely attractive!
The team also agreed upon the need for a substantial amount of connecting infrastructure — i.e., conduit and cable access throughout the facility to allow future changes in technology or equipment to be more easily supported. However, with a building less than four stories tall set on nine separate floor levels (due to the many expansions built on to the structure over more than 90 years of the church’s history), getting conduit, ductwork and power distribution throughout the facility, while maintaining acoustic isolation, proved difficult.

In several cases, the limited amount of space within the existing structure required the team to use additional acoustical treatments, which increased costs but allowed us to fit the full eTown program into the space. One example of this is the HVAC duct work serving the studio. We were able remote most of the HVAC system’s compressors and heat exchangers on the roof. However, several fan units were located in the space above the studio’s control room, which required that a great deal of the ductwork above the studio be wrapped in high transmission loss duct wrap. This wrap is both costly and heavy, which makes it difficult to work with. But without it, our control room would be substantially degraded by excessively high HVAC noise, and alternate locations were either not viable or substantially more costly than wrapping ducts.

The Sound System

As of this writing, the technical systems for the facility were still under design review. However, the main PA has been installed. After reviewing many options, a small-format line array system featuring a high power HF ribbon loudspeaker was selected. Two five-element line arrays using the Alcons LR14/90 unit (which incorporates two 6.5-inch woofers and the RBN401 pro-ribbon HF driver) were selected.

The choice of the Alcons LR14 was the result of critical listening and a deep understanding of the music eTown features. These days, there are a large number of great-sounding loudspeakers to choose from. Nick built his career in acoustic music, and he loved the sound of the Alcons ribbon driver when he heard them demoed in Las Vegas. Given the small size of the performance space, the smooth, low-distortion high frequency response of the Alcons pro-ribbon is a particularly good fit for reproduction of acoustic music.

Traditionally, ribbon loudspeakers have failed when asked to generate large amounts of energy and have been prone to reliability issues. Alcons claims to have solved these issues with its globally patented pro-ribbon technology, which is a hybrid ribbon/planar device utilizing a flat wound voice coil and unique thermal management design as part of the motor structure.

Consoles will be the Avid VENUE Series, with a Profile at FOH and an SC-48 as the monitor desk. Both of these consoles were chosen for ease of use, their ability to provide recall, plug-in capabilities and, of course, sound quality.

eTown Hall is scheduled to open this summer, with a full schedule of shows starting in August 2012.

Author Sam Berkow is the principal consultant at SIA Acoustics and creator of SIA-SMAART audio analysis software. Visit him at siaacoustics.com.