THEATRE IN THE ROUND
Jun 1, 2000 12:00 PM, David Drommond
Utah is well known for its snow, spectacular National Parks and culturalattractions like Temple Square and the world-famous Mormon TabernacleChoir. Now, there is a new cultural attraction in the Salt Lake Valley thatis drawing rave reviews - a performing arts facility that has been called"the finest center-staged theatre in the world."
The Hale Centre Theatre in Utah's West Valley City has won architecturalawards for its unique design, and it is winning theatre patrons in drovesfor its brilliant combination of high-tech staging and intimate atmosphere.A key component of the success of the theatre's design is the sound system,which serious theatre fan Neal F. Bradshaw describes as the best he hasever heard. Neal's opinion carries some weight because he is the seniordesigner and group manager of the architectural division for the LDSChurch. He has experienced sound systems in hundreds of buildings andtheatres. Creating the sound system that would complement the HaleTheatre's state-of-the-art design presented some interesting challengesthat will be addressed in this article, but before getting to the nuts andbolts of the sound system, let me set the stage for you.
More than $7 million was invested in the construction of the Hale Theatre;that it was money well spent is evident at first sight. The exterior is aneo-traditional design that invites the eye. An approach after dark isespecially pleasing because of the accent lighting that graces the buildingfrom top to bottom. The exterior design disguises the mass of the building,which houses a main theatre, four rehearsal halls, eight dressing rooms, akitchen, concession stands and extensive costume storage.
Inside is a traditional grand staircase leading to the second level.Chandeliers, wood trim, stained glass, and special lighting contribute toan atmosphere of warmth and intimacy. The main theatre seats 531 peoplearound its center stage. Eight rows of seats on risers arranged in anoctagon guarantee that every person has on unobstructed view of theperformance. Competing with the actors for attention is the stage itself, aunique design costing about $1 million. Multiple platforms can raise andlower independently of one another over a range of 16 feet (4.9 m) and canrotate in both directions while the center platform rotates in the oppositedirection. Revolutionary computer technology controls the stages, lightsand sound system.
Speaking of which, the sound system has become a more critical component ofthe modern performing arts facility. Audiences, increasingly sophisticated,expect a high-end concert-hall quality of sound experience. To provideanything less would significantly reduce the perceived value of the entireHale Theatre experience.
Slaying acoustic dragons
The acoustic challenges at the Hale Theatre were significant, to say theleast. The building is located less than a mile from the Salt LakeInternational Airport glide path, about a hundred yards (91 m) fromInterstate 215, and is fronted by a busy concrete-surfaced street. Let usreview what was done to slay these acoustic dragons, starting with theexterior of the building.
In days of yore, dragons were slain by knights. Acoustic dragons, however,are slain by acoustical consultants. Acoustical consulting involves anunderstanding of physics, acoustics, electrical engineering, and plainhorse sense. The environmental noise elements mentioned above required thatwe use all of our knowledge and experience. Sound Design Internationalconsulted with the other members of the design team for the design andconstruction of the Hale building as well as the choice and placement ofthe sound hardware.
Noise from incoming and outgoing airplanes presents a special challengebecause the noise source changes in both volume and pitch. In a quietenvironment, an approaching airplane gets louder and its frequency (pitch)changes. As a plane flies over, the pitch changes, but the noise abatesback to the quiet setting. This movement from quiet to loud to quiet, alongwith the pitch change, creates the noticeable, unwanted condition.
Although the airplanes were a major nuisance, the freeway was an evengreater concern. This type of noise source is a line radiator; the noisedrops only 3 dB per doubling of distance. In comparison, a point sourcedrops 6 dB for every doubling of distance (inverse square law).Unfortunately, we could move neither the freeway nor the building.
Compounding the problems with the airplanes and the freeway traffic was thecement-surfaced street that passes in front of the theatre. A car or truckdriving on cement creates more noise than on asphalt, and the noise ofemergency vehicles screaming past the hall cannot be tolerated inside.These conditions provided still another source of random changes inloudness and pitch.
After studying, measuring and carefully calculating, we requested an EIFS(exterior insulation finish system) on a block wall with the cells filledwith sand, the outside sealed with a heavy paint and the inside finishedwith two layers of sheet rock. Further, the orientation of the building waschanged so that the front was not directly facing the freeway. This allowedfor the directional noise to glance off the walls, reducing the penetrationof offending sounds. Windows and doors are the weak points to a hightransmission loss boundary. We requested a reduction in the size of theplanned windows, the addition of multiple glazing, and vestibules for thedoors - all of which really helped our cause. Finally, the roof alsoreceived acoustical attenuation to create a uniform sound barrier from theunwanted exterior noise. The proper noise shield was provided by roofingmaterials, insulation filling the void and sheet rock.
Taking care of the exterior noise was only the beginning. The interior ofthe building also presented some interesting challenges. The design goalsmandated that every discipline would help to increase the intimate feelingof the theatre. The room was designed for the best possible acousticsbefore the sound-reinforcement system was even considered. Our designrequired an angled rear wall and an angled ceiling behind and above all theseating for the best early reflections into the audience area. By doublingthe sheet rock on the angled rear walls and ceilings, the base energy isretained in the space.
The interior design has some positive and some negative features for noise.The walk-about corridors surrounding the main theatre are a blessing. Thisarea adds to the isolation to keep both externally and internally generatednoise from getting into the main hall.
At our request, the mechanical engineer responsible for the building'sheating and air conditioning used fiberglass-lined ducts, multiple 90degrees duct angles with turning veins and low-velocity air flow from thesystem into the theatre. This system under full load is totallyunnoticeable in the room.
The cupola above the main stage (fly loft) had to be treated withabsorptive material (6 inch or 152 mm black fiberglass batts) to keep thenatural sound from the stage from being dumped back onto stage as adiscolored echo. During construction, similar absorptive material was alsoinstalled in the orchestra pit walls to reduce the noise created by thestage motors and prop handling.
Because of the high water table on the property, a water pump was requiredin the basement. A submersible unit was used so that pump noise would notpropagate into the theatre stage area.
Controlling exterior and interior noise is important and the entire designand construction team cooperated with our directions to maximize noiseabatement in their areas of responsibility. On the other hand, controllingnoise is only half the battle. The other half is to design and install asound system that meets high expectations for quality while accommodatingthe special requirements of theatre in the round.
The sound system
Theatre in the round requires a unique approach to sound-system design.Unlike a normal theatre where the actors are usually working from thestage, theatre in the round actors can be anywhere - the main stage, theauxiliary stages, even in the aisles. Sound reinforcement is requiredeverywhere.
A tough thing to do is to get an ears-in-the-theatre mixing location.People who are not well informed often think that the mixing board shouldbe placed in the theatre by eliminating a paying customer's seat. Thearchitect accommodated the sound control system rather well by putting itin a great location with lines of sight to every part of the theatre.Operational noise (from equipment or rigging) is cut off from thenoise-critical part of the control booth by a wall and a door. Sometimesthe worst critics of a sound system are the operators, but not in thisvenue. The operators at the Hale Theatre are capable engineers and wereinvolved on the design team from the beginning.
The Hale Theatre sound system consists of 72 mic inputs in the catwalks,stages and pit; a 48 input mixing console (Allen & Heath GL3300),computerized program hard disk storage, 16 AKG WMS-300 wireless mics and aRane RPM26V DSP (digital signal processor) for broad and narrow bandfiltering. The amps, consisting of Crown CE 1000, CE 2000 and K-2 units,are all placed together but distant from the mixing location and theatre tokeep the fan noise from disturbing the audio engineer or the audience.
The optimum main house loudspeaker design would have been a centralcluster. In our case, the compromises that plague every design required theloudspeakers, mostly JBL SP212s, to be installed in an exploded clusterarray. This compromise was necessary because the fly loft over the stage isas large as the main stage. The loudspeakers could not interfere with thescenery being lifted from or dropped into place. The bottoms of thecatwalks were the next best location for the loudspeakers.
After the direction had been determined, loudspeaker selection, location,direction and rotation were engineered. EASE (Electro-Acoustic Simulatorfor Engineers) and EARS (Electronically Auralized Room Simulation) wereused to verify that the design was correct and to tweak the coverageangles. These computer programs are powerful allies. They permitted us tomodel and virtually listen to the room and sound system before the hall waseven constructed. Like any tool, the programs are only as effective as theoperator. Experience is the key. In inexperienced hands, they can lead tosome poor decisions about system design and layout.
Where to install the subwoofers? From the front row of seats to the stagefloor is only one step; there is no room on the floor. Flying the subs, EAWSB150Rs, under the catwalks would not be as effective as having a large,acoustically hard surface with which to couple, so the ceiling was chosen.The subs were installed touching the ceiling as high up as the ceilingwould permit. This increased the subs' efficiency by creating a soundpressure wave strong enough to shake the audience and add to the realism ofthe productions. If you want thump, you get thump.
Three special-effects loudspeakers were placed at every entry on the mainlevel and 10 on the second level. This setup permits sound effects that arelimited only by the director's imagination. A train can be sent racingthrough the room, or you can hear rolling thunder that is so realistic itmakes you want to dive under the seat.
Loudspeaker outlets were installed on the main stage and also on the threeauxiliary stages to feed program material to the loudspeakers placed underan old phonograph, telephone, television or other props. This allows forthese special effects to be cued and controlled from the sound booth.
The main system was balanced and equalized with the use of two valuabletools - a SmaartPro analyzer program and two human ears connected to thepowerful gray-matter computer that sits between them. No amount of advancedtechnology can replace the natural hardware with which humans have beenblessed.
The electrical engineer provided an isolated ground for the sound systempower with a TVSS (transient voltage surge suppressor). This measure helpedto keep all the electrical noise out of the sound system.
Moreover, the theatre operator wanted to be able to pre-record a show'ssound and music on the sound computer, record all of the lighting cues onthe lighting computer, store all of the motorized stage cues on itscomputer and then tie all three systems together. This arrangement requiresonly one person to man the control booth. Manpower and the need forcoordination were reduced, but it does place a lot of responsibility on oneperson.
Other electronic components included in this project were the paging/alertsystem, CCTV (closed circuit television) system (a Blonder Tongue unit withPhilips CCTV cameras), the theatrical intercom system (ClearCom WBS), andthe assistive listening system (Williams Sound PPA 250E transmitter and PPAR7E receivers). From the ticket office or the control booth, all call orzoned tones can be generated to call the patrons back from intermission orto cue the actors. Loudspeakers are even installed in the restrooms. Thissame system is also used for paging at times other than during aperformance.
The CCTV system has a camera in the main theatre with televisions in thefireside lounge, administrative offices, ticket office, rehearsal halls,green room, lighting booth and pit. Most of the televisions are used to cuethe staff and actors, but the television in the fireside lounge is for thepatrons who arrive late. They can watch the production in this room untilintermission and then take their assigned seats without interruptingothers. Now if we can just get them to turn off their pagers, telephonesand watches with alarms.
The project was a great opportunity to work with some professional andtalented people. By cooperating and coordinating our efforts, the designand construction teams were able to create a world-class performing artsfacility whose beauty and technological features make it a major gem in thecultural diadem of the Salt Lake Valley.
If ever you find yourself in Salt Lake City, plan to attend a production atthe Hale Centre Theatre. Successful theatre, it is said, depends upon theaudience's willingness suspend disbelief. Perhaps so, but when the directorcues the cannon-fire light and sound effects in the Hale Theatre, Iguarantee that you will be reaching for your helmet.