- When the management at the Edward Jones Dome in St. Louis, home of the NFL's St. Louis Rams determined that they needed to improve their music playback capabilities, they decided that adding speakers, subwoofers and amplifiers to the main system was not the best solution.
They wanted a sound system that would be flexible enough to work for football games as well as for a number of other functions held at their facility year-round.
For their solution, they turned to Tony Badamo, pro sound and AV specialist at Tech Electronics in St.Louis to configure and package their new on-field systems that would provide the audio quality and flexibility they required.
Badamo determined that four full-range vertical array / subwoofer stacks placed at each corner of the field would cover the stadium's large floor area and be heard above the crowd. This concept would offer the coverage and use flexibility that the stadium was looking for.
Each system was required to deliver 128 dB SPL with a frequency range of 33 - 20,000 Hz + / - 3 dB. In addition, each stack had to be easily movable by one person, fast to set up, yet deliver high output and be capable of projecting its sound long distances. The stacks had to be self-contained including its own mobile cart, power amplifiers, processing and all AC cabling. Each full-range speaker and subwoofer had to be permanently attached to each other.
Additionally, the amplifiers had to deliver sufficient power to ensure 3 dB of headroom and each stack had to operate from a standard 20 A / 120 V ac circuit and had to include 15.15 m / 50 ft of ac mains cable. The overall rig could be no taller than 1.8 m / 6 ft so that it could be moved through the stadium's tunnels onto the field and so that sightlines weren't interrupted.
Ultimately, each of the four stacks consists of 1 x One Systems 312CIM, 1 x On Point Audio OPA-218-Sub and 1 x Powersoft K3 DSP amplifier. One channel of the Powersoft amp drivers the 312CIM; the other drives the OPA-218-Sub.
The 312CIM is a vertical array loudspeaker system featuring three 12-inch woofers with 4-inch voice coils and a large-format, coaxially mounted compression driver. The 312CIM provides 1,200 watts continuous, 4,800 watts peak power handling and 60-degree conical HF coverage.
The OPA-218-Sub utilizes two powerful 18-inch woofers with 4-inch voice coils housed in a Vented Slot enclosure featuring 1,600 watts continuous, 6,400 watts peak power handling.
Because the subwoofer enclosures are short and slim but very deep, they were perfect for attaching the 312CIMs on its top. To make the system easy to move and connect, they turned the OPA-218-Subs upside down and installed large-diameter locking casters on the bottom of the enclosures. Turning the subwoofers upside down exposed two CNC cut handles which made moving the assembly easier and more comfortable.
In addition to the 312CIM, a 5 RU metal rack was also attached to the top of each subwoofer to house the Powersoft K3 DSP as well as drawers for the long AC and XLR-type signal cables.
"The system delivers everything that the Edward Jones Dome asked for," concludes Badamo. "It has tremendous bandwidth, high output and it shakes the building when it's played while still delivering the sonic nuances of the music perfectly."