Shure Squeezes Into the Spectrum Under the Shadow of Mt. Wilson

June 17, 2009

MONROVIA, CA, JUNE 17, 2009 — Man alone, in a hostile environment: If there's anyone in pro audio short on existential moments these days, one of the grandest in terms of wireless systems design can be found at the Monrovia High School Auditorium, which lies right under the shadow of Mt. Wilson, a 5,715 foot peak northeast of Los Angeles in the San Gabriel Mountains.

 

Known among astronomy buffs as the location of Southern California's Mt. Wilson Observatory, the mountaintop is also a metro-media center for relay broadcasting of radio and television frequencies heard and seen across the greater Los Angeles region. With an imposing antenna farm perched at its summit, the site bombards the Monrovia High School below with RF of a magnitude that is hard to find just about anywhere else.Monrovia High School

 

That's why Temecula, California-based Jeff Dykhouse of WorshipMIX, an AV design and production house, had one of his most recent existential moments when he was approached  about designing and implementing a 24-channel wireless system for the school auditorium. Slated for use with the school's theatrical presentations and other events, the system was designed to exist, quite literally, in the eye of a very serious RF storm.

 

"There are more than 20 TV and radio stations broadcasting from the top of Mt. Wilson at ranges of up to 166,000 watts," says Dykhouse, who chose Shure UHF-R® wireless transmitters and receivers for his assignment. "Using Shure's Wireless Workbench® on my Mac, I turned on my receivers and let the software randomly assign frequencies for my 24 channels. More than two-thirds of the channel meters were pegged from interference, and I hadn't even powered up a single transmitter of my own."

 

Working with Jeff Suchy of Apex Audio in Huntington Beach, Dykhouse chose Shure UHF-R in part because of an inherent design that enables users to place transmitter frequencies in close proximity to one another, a vital consideration given the crowded nature of the RF environment.

 

"We also gave additional value to the Shure product based on its auto frequency locator, which seeks out open space in the spectrum based on information gathered from a central database as well as what it finds in the environment itself," Dykhouse explains. "I tried it both ways and still couldn't find a home for all of our transmitters; there was still interference. One of the biggest problems was that some of the interference wasn't continuous."

 

In Dykhouse's Plan B of attack, he called on another Wireless Workbench feature that enabled him to scan over long periods of time. Letting the software analyze the environment for four hours, he used the collected data to go back in and close the gaps.

 

"The last hour or so didn't reveal anything new in terms of interference, so I manually placed my transmitters in the only available spaces and things began working," he says. "Jeff Suchy chose two bandwidths of operation. When you see them mapped out on Wireless Workbench, they look like the craziest choices available – open spaces were few and far between. There was method to his madness, however. We designed the system prior to the DTV transition on June 12. Once analog TV broadcasts were suspended, the blueprint took on a clearer face. In the meantime, pre-transition, the school put on a presentation of Sweeney Todd using 20 of the 24 UR1 bodypacks we provided, and the play navigated its entire run without so much as a hiccup."

 

In addition to 24 UR1 bodypacks that are used with Countryman E6 omni earset mics as well as Sanken COS-11 omni lavs, 12 of Shure's UR2/58 handheld transmitters were incorporated into the design. All share the resources of the 24 channels of Shure UHF-R receiver power as needed.

 

Beyond having the distinction of residing right in the path of some of the meanest RF activity in the U.S., Monrovia High School is unique in that its school board president is Chris Rich, a freelance production mixer who works on broadcast assignments that include the NBC game show “Deal or No Deal.”

 

"We initially went searching for our own wireless system based on the poor performance of the past rental systems we used," Rich notes, citing some of the bleaker moments in the 700-seat auditorium's wireless history. "Shure was on our mind once we made the decision to build our own system. I've had great success with the units over the years and am currently using 30 UHF-R channels on ‘Deal or No Deal’ without any problems."

 

Sweeney Todd ran at the auditorium from April 23 of this year to May 2. Future events promise to bring more dramatic presentations to the room as well as live musical performance. The wireless upgrade in the school's auditorium was funded as part of a wide-sweeping renewal project taking place all across campus.