Fixed Mixes: One Custom Clean Install
A High-End Shed System System Not Far From Lake Erie
Northeast Ohio’s world-class outdoor amphitheater, the Blossom Music Center, recently invested in a new sound system worthy of its reputation. Blossom boasts nearly 5,000 canopy seats, and 13,000 lawn seats, and is arguably one of the best symphonic amphitheaters in the world.
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Originally built in 1968 by dedicated patrons as a summer home for the Cleveland Orchestra, Blossom has hosted popular and classical artists of every genre from Janis Joplin to Nine Inch Nails to Natalie Cole. Each summer, the orchestra settles into a Thursday through Sunday
schedule, playing everything from Mozart to Marvin Hamlish. |
OLD SYSTEM BLUES
Blossom Music Center’s old sound system was the inevitable mis-designed
amalgamation of audio technologies spanning the 1960’s, the 90’s. During
this time, Blossom brought in new equipment not to overhaul the system,
but rather to Band-Aid problem areas that had degraded from poor to unusable.
The rigid conduit that held snakes and return lines had rusted through,
and the alkali in the cement had commenced dining on the succulent snake
jackets. Factor in all of the mechanical infirmities, an RT60 of 4.2 seconds,
and you have the formula for an extremely challenging project.
Our sound design and installation company, Caravan, originally began working
with the Cleveland Orchestra in 1992. At that time, we began reinforcing
their annual July performance for the citizens of Cleveland on Public
Square.
During the years that followed, the event grew in stature and complexity,
incorporating three video screens, a pyrotechnics display, and a light
show. Caravan now reinforces the orchestra’s public square performance
for well over 60,000 spectators. In addition to sound design and installation,
we also manufacture the Caravan Protective Cases.
The Musical Arts Association, which owns Blossom, allowed us to install
temporary snakes and return lines, along with temporary cabinets on a
delay ring for the back two-thirds of the house before the real improvements
began. While the Musical Arts Association developed a multi-year plan
to renovate the facility, the sound reinforcement system took precedence
and was step one of phase one in the 2001 improvements.
We set stringent, specific design goals. First, we wanted a distributed
system with 100% articulation throughout the seating area and only a scant
+/-2dB deviation from front to back, and from side to side. Next, because
every orchestral event at Blossom is recorded, we wanted a system completely
devoid of noise.
Third, because the system is outdoors and because Ohio winters are hardly
“climate controlled”, we wanted a rig that could be seasonally installed
and removed with minimal labor.
We also wanted to use as much of their existing inventory as was possible
within the quality context. Finally, we wanted to keep the system simple,
intuitive, and robust. Blossom shouldn’t have to think about their sound
system for a long, long time.
LOUDSPEAKER CRITERIA
As a subset of those criteria, we required high-Q, passive loudspeakers
that were all horn-loaded and lightweight. This directionality would keep
the amplified sound from reflective surfaces in an effort to avoid exciting
the amphitheater’s ample capacity for reverberation.
We sought simplicity, efficiency, and a passive characteristic to keep
the number of amplifiers and minimize external processors. We also chose
to rely on only one loudspeaker manufacturer, as previous experience with
tuning venues rife with different loudspeakers produced frustration, and
lack-luster results.
It is difficult to make smooth transitions from cabinet to cabinet, in
a difficult facility, when cabinets characteristics and responses vary
widely. We tried a number of cabinets and found that only the Sound Physics
Labs SPL-td1 met our criteria.
Designed by legendary engineer Tom Danley, the SPL-td1 uses a one-of-a-kind
technology that combines the outputs from several drivers to drive a single
horn. Each driver is allowed to operate within its frequency range.
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Unlike other “nested” designs, the result is a flat frequency response that is automatically time/phase correct simply in virtue of the acoustics involved. The cabinet houses two 12in low frequency drivers, four 5&1/4in compression loaded mid-frequency drivers, and a 1in high frequency horn in a unique Unity Summation Aperture (Patent Pending). |
In addition to fidelity, the design results in amazing directionality,
and, consequently, improved efficiency. Sound Physics Labs sent us a pair
of SPL-td1’s to demo. We connected these at Blossom, and found their sonic
properties a perfect match for our design. In total, fifty-seven SPL-td1’s
comprise the distributed system.
Our intent was to place the loudspeakers such that each patron was in
the nearfield of a given loudspeaker. Thus, close loudspeakers effectively
mask reflected sound, keeping intelligibility high and overall volume
levels low.
We divided the pavilion area into three sections, each of which were covered
with a specific loudspeaker arrangement. Twenty SPL-td1s, in an upfill/downfill
arrangement, cover the bulk of the lawn, and stage poles cover the outer
fringe.
LCR COVERAGE
Seven SPL-td1’s cover the first third of the pavilion in a left-center-right
configuration. Left and right paired loudspeakers form the clusters, while
three loudspeakers combine to form the center array. We angled each cabinet
at 45°s to focus the energy on the first third of the house. Caravan custom
brackets trimmed to a height midway between the stage deck, and canopy
support the center array.
All seven loudspeakers “fly away” on CM ProStar motors via Motion Controls
on 1001 umbilical cables when rock shows bring their own on-stage loudspeaker
systems. Eight EAW JF-6070V loudspeakers fill in the first four rows.
Next in line are eleven SPL-td1’s spaced evenly across the downstage edge
of the canopy and angled at 55°s into the middle-third of the seating
area. The innermost loudspeakers bow out relative to the outer-most loudspeakers
fitting the architecture of the canopy.
Except for the center loudspeaker, each loudspeaker is paired with its
“mirror image” for delay processing via a Peavey 1000 Multitap Digital
Delay and amplification (e.g. loudspeaker #1 is paired with loudspeaker
#11, loudspeaker #2 is paired with loudspeaker #10, and so on).
The significant arch of the canopy presented a mounting challenge that
excited our shop personnel. We needed a universal mount that would fit
any of the eleven canopy positions (see Photo #1) and still allow the
cabinets to hang level and angled at 55°.
The elegant solution involves both a temporary mast that users insert
into a sleeve and a block and fall that users attach to the rigging. Once
those pieces are in place, users can easily raise or lower the loudspeaker.
MID-HOUSE AND LAWN SYSTEMS
The mid-house system (see Photo #2) covers the rear third of the canopy
section and is configured like the eleven loudspeakers described here.
Peavey IDL 1000 delay lines compensate for the radius and the increased
distance from the stage, and each loudspeaker is electronically paired
with its “mirror image”.
Differences in the mounting demanded we construct a unique stainless steel
two-winch system and rigging to raise and lower the loudspeakers for seasonal
installation and removal. We covered the bulk of the lawn section with
twenty SPL-td1’s mounted in ten bays that span the width of the lawn.
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Fortunately, the SPL-td1’s fit the bays within an inch, allowing us to utilize the existing structures. We mounted them sideways and within each bay faced one loudspeaker uphill and the second loudspeaker downhill. Again, we paired each loudspeaker with its “mirror image” for common amplification and delay processing. |
Two stage poles deliver sound to the outer fringes of the lawn. Four
SPL-td1’s are mounted per pole and splayed for a dispersion pattern of
120°s. These were especially easy to array, due to the “point source”
characteristic of Danley’s unique design.
When we placed the SPL-td1’s together, there were no comb filters or gaps
and the individual “point sources” effectively melded into one large “point
source”.
The stage poles are currently located 75ft(22.8m) offstage, an artifact
of the old sound system. At the end of the season, the speaker and poles
will be relocated closer to the pavilion.
TIME DELAY & EQ SET UP
Once all of the SPL-td1’s were in place, we spent five days using a combination
of audio software and Audio Control’s Iassys hardware, adjusting and tweaking
delay times. Our experience confirms that no amount of equalization will
compensate for time smear.
Consequently, the tuning process is much more relaxed and efficient once
we lock the delays in. Between Smaart and Iassys, we got within a few
milliseconds of where we needed to be. Still there were times when Blossom’s
ample reverberation confused Iassys.
We relied on 2kHz test tone (anything below that excited the room too
much); a laser tape measure, math, and our ears to smooth the system out
as much as possible. Once time delays were set, we took frame shots of
a single SPL-td1, two SPL-td1’s, and three SPL-td1’s, and equalized the
center three-box cluster to match the two-box left and right clusters.
With the LCR speakers as reference, we proceeded to equalize out the room
modes. Even after that, we observed a considerable resonance centered
on the canopy shell (see Photo #3) and soon discovered that the low frequencies
from the eleven canopy mounted loudspeakers were coupling with the band
shell.
We put these speakers on highpass filters and gradually increased the
cutoff to 150Hz. With the LF removed, the canopy loudspeakers acted more
like fill boxes and gave us the articulation we desperately needed at
the mid-house area.
The old sound system made use of an infinite baffle-type center cluster,
and the LF build up coupled with the slapback from the rear ceiling. This
necessitated on-stage monitoring for everything, including simple narration.
Because the horn-loaded SPL-td1 radiates little energy off the back of
its enclosure, the new system is much more directed and clean.
POWER & PROCESSING
The Musical Arts Association records most of the orchestral performances
at Blossom either for archives, or for future broadcast. Consequently,
the sound system had to be absolutely noise free. To this end, we installed
a new isolation transformer dedicated to the sound system that feeds a
Lynn Tech sequential power-up panel.
The panel in turn powers the equipment racks, which is isolated on a 1/4in
rubber pad. All conduits were stubbed into PVC nipples to prevent any
common grounds. Four Equi=Tecs provide balanced system power.
We dedicated one unit to the MediaMatrix, KT distribution splitters, and
Peavey IDL 1000’s. Respectively, second unit was dedicated to the recording
room, a third to the house rack, and the final unit to a “road rack” for
rock show docking.
All of the feeds from the FOH position to the Media Matrix are transformer
balanced. With every precaution taken, the idle system is not much louder
than a stonewall!
All of the microphone and drivelines are configured as home runs to ProCo
custom panels with gold-plated XLR jacks. Microphone lines terminate in
an XLR patch bay in the amplifier room. Two Klark Teknik 1248 distribution
amplifiers provide the splits that send microphone signals to the FOH
position, the recording room, and the monitoring position.
Remote positioned Midas preamplifiers allow engineers to use FOH or monitoring
console for level control and bussing. An Anchor self-powered monitor
is plugged into the 1248s cascaded solo buss, which allows users to check
a microphone signal before making a patch.
A 24-channel Crest X8 sits at the custom-enclosed FOH position with three
KT 3600 digital EQs and three DBX 160x compressors available to patch
as inserts. We selected the 3600s with an eye toward longevity. They don’t
have faders.
Two Mackie monitors are tuned to match the lawn system and delayed to
the main mix. Engineers use the Mackies for soloing and as a lawn mix
reference. The orchestra monitor system consists of twelve Galaxy Hot
Spots powered by a Crown 1610 amplifier.
WELL RECEIVED
With the system up and running and the summer season well underway, the
new installation is receiving critical acclaim. Beyond elimination of
the old system’s problems, Blossom’s overall sonic quality now rivals
any premier outdoor venue worldwide.
Rick Galbraith is president of Caravan Industries.
July/August 2001 Live Sound International