The Electronic and the Acoustic
Developing systems to be heard but not always seen at Disney Concert Hall
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Sixteen years ago, the late Lillian Disney, widow of Walt, bequeathed
$50 million dollars to the Music Center of Los Angeles, with the
funds to go toward the building of a world-class concert hall as
homage to the Los Angeles Philhar-monic, and to music itself. |
The architecture is both stunning and unique; completely unlike anything
else bordering its 3.6-acre lot. Architect Frank Gehry ensured that visually
and sonically, the Walt Disney Concert Hall would indeed evocate music.
The gentle curvature of the building is reflected inside as well. The
centerpiece of the 2,265-seat auditorium is an open platform stage with
360-degree padded seating, carpeted floors and a majority of vertical
and ceiling surfaces of Douglas fir wood.
WORKING IN CONTEXT
“We were given a hall with an acoustic design,” says David Clark, director
of audio engineering and project manager at Engineering Harmonics of Toronto,
referring to Gehry’s design consultations with acoustician Yasuhisa Toyota
of Nagata Acoustics in Tokyo, Japan. “The technical challenge was to find
loudspeakers that could work in the acoustical context. There is no variable
acoustic system in the hall. Many halls have acoustic systems that can
move, or acoustic damping can be brought in. This hall doesn’t. We were
given a done deal in terms of acoustics.”
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Clark began his journey with the project in 1999, when his firm
was approached by Gehry Partners to design a sound system for the
hall. Earlier, the construction of the hall had been halted due
to funding issues. The only existing portion completed at that time
was the subterranean parking structure partially jutting from the
ground. |
Since all the players came to the table with different objectives and agendas, we created a roadmap that we could all support. The roadmap outlined the program requirements, how the system would be operated and technologies to make it possible.”
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The team at Engineering Harmon-ics, which included Clark as well as Phil Giddings, Martin Van Dijk and Paul Alegado, faced a considerable task. They were to provide designs for three separate and discrete sound
systems: a voice-only announcement system for the auditorium, a
high-end sound reinforcement system for performances and a paging
system for the lobbies and backstage. |
To install these systems, the owners and Engineering Harmonics chose
ProSound (Miami, Orlando, Las Vegas, Los Angeles). Larry Spurgeon, president
of ProSound Las Vegas, served as project manager with Scott Marcellus
providing systems engineering for the install. Jack Valencia served as
the rigger on the project.
Clark worked closely with Ted Leamy, director of custom project management
for JBL Professional, to provide the loudspeakers for the project. Leamy
joined JBL Professional in 2000 after 23 years with touring company Electrotec.
“In fact, when Dave and I first met, our initial conversation was about
the hall,” says Leamy. “The marriage of each of the loudspeaker sub-systems
and how they would interact was an extremely important part of the discussion
right from the beginning.”
ANTIPATHY TOWARD TECHNOLOGY
For the announcement system, there was only one small catch: it had to
be 100 percent concealed. “It is a criterion in symphonic halls that you
can’t see the sound system. That is because a lot of symphonic listeners
believe that if there is a speaker that they can see, then it must be
on and they are not hearing the real thing,” notes Clark. This antipathy
towards technological assistance presented a serious design challenge.
As such, the announcement loudspeakers, which are JBL AM6200’s, are mounted
in the ceiling behind custom wood grilles. The enclosures have been deconstructed
and the components protectively packaged and framed in drywall enclosures.
These are supplemented by the front fills, concealed in the stage lip,
which allow the audience to hear the stage manager or the maestro speak
without conscious knowledge of any loudspeakers.
The sound reinforcement system would be put to use when the Philharmonic
was not using the hall, like during the summer months when they are performing
in their summer home; the Hollywood Bowl (For more on system work at this
venue, see Live Sound September 2003 issue). Because the Music Center
would be running a wider program during the Philhar-monic’s off months,
the sound reinf-orcement system had to focus on performance, but again,
without compromising the aesthetic integrity of the auditorium.
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“There was no way to hide the loudspeaker system so the design
decision was made that the performance system would not be hidden,
but put in the open above the stage,” says Clark. “I picked line
arrays for the acoustical benefits, but also they have the curvy
look that mimics the Frank Gehry aesthetic.” |
Additionally, three mid-high cabinets embedded in a vertical soffitt at
the rear of the auditorium cover the upper balcony in mono. Three small
arrays cover the “chorus” seating behind the stage, and these are comprised
of JBL AM6212 two-way loudspeakers. Crown MA-5002VZ, MA-3600VZ and MA-2402VZ
models make up the 50 total amplifiers that power both the voice announcement
and sound reinforcement systems.
All of the suspended arrays are stored on dollies offstage and rigged
up when needed. The chains run through four-inch holes in the ceiling
attached to inverted chain motors, which are in turn attached to the steelwork
above.
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MARKED FOR REPEATABILITY |
For the rigging setup, ATM Flyware developed a custom swivel bar that mated to the exoskeletons of the arrays. The swivel bar made it possible to adjust the array’s yaw, or rotation from left to right, then lock the setting in place. This addressed the design requirement for field adjustable pitch and yaw for the system.
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The performance system had to be system engineered for the acoustics
of the hall since its surfaces were so highly reflective. Modifications
were made to some of the horizontal coverage patterns in the VT4888
and VT4887 loudspeakers to take into account the reflective surfaces
in the room. |
In order to work in the reflective environment, the loudspeakers are hung
high to shorten the reflection path for most seats, which is perceived
as a stronger reinforced sound rather than an echo or a phase cancellation.
Line arrays deliver a big wedge of precise, controlled sound to the seats
and not to the wall above, minimizing long reflections. Clark carefully
modeled the system with 3-D CAD and JBL’s line array optimization program
and then made on-site adjustments.
“If you look at the volume of the hall, the seats are in the bottom half,”
he adds. “We needed to keep the sound down towards the seats without spillover
onto the upper surfaces.”
Also due to this highly reflective environment, a removable screen with
acoustic treatments was added to cover the control room windows on the
orchestra level when the mix position is brought out in front of the house.
The architects provided the screen so that there is no hard reflection
from the windows into the back of the mixer’s head.
MAKING IT FIT
The remainder of the performance system includes eight JBL ACF4325 front
fill loudspeakers and seven JBL VT4881 subwoofers, which are alternately
spaced and hidden under the stage. Latticework and grilles were added
to cover the front of the stage allowing them to be hidden but still heard.
The outer two sub enclosures had to be re-engineered by JBL to fit within
a smaller space.
“Where the seat risers intersect the front of the stage, there is less
vertical room under that part of the stage than anywhere else. Because
the subs had to remain under the stage, we had to alter the aspect ratio
and profile of the VT4881 enclosure to make it fit without sacrificing
performance,” says Leamy.
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Space constraints presented a bit of a challenge in the desire
to have the subwoofers lined up beneath the stage. Because the stage
forms a shallow horizontal arch, the subs had to be positioned so
that they lined up, subsequently forming a line array. |
Clark also used SoundWeb for the two separate DSP networks running Walt
Disney Concert Hall’s performance and paging systems. “They are kept separate
to prevent failures in one from contaminating the other. Specifically
failures in the paging system are prevented from causing failures in the
sound reinforcement and voice systems.”
DSP also allows recalibration of the system on the fly, as well as easy
operation at the touch of a button. This can be helpful given the number
of artists that will perform at the hall in the coming months and years.
“The Walt Disney Concert Hall is certainly one of the most challenging
spaces we’ve had the opportunity to work with,” both Clark and Leamy note,
almost simultaneously. The venue opened its doors to the public in late
October with the first of three inaugural galas showcasing the Los Angeles
Philharmonic and the Los Angeles Master Chorale. Future plans at the site
include a sound reinforcement system for the Garden Amphitheatre.
Linda Seid Frembes is a veteran pro audio journalist and can be reached at seidfrembes@yahoo.com
November 2003 Live Sound International