ABOUT THE SPACE

Glenn Thompson from XConnect Professional Services consulted on the project. Glenn is well known in these parts as a PA systems specialist, having been instrumental in the audio upgrades at Suncorp and Cbus Super Stadiums in and around Brisbane.

“Acoustically, the venue is actually quite good. It’s fairly tame compared to other theatres, with lots of soft surfaces such as carpet and fabric, and a ceiling that doesn’t reflect too much sound. So we had a really nice canvas to work with.

“The seating is arranged in three blocks, which naturally lends itself to an LCR loudspeaker configuration. From the beginning, we were leaning towards a compact line array system, augmented with subs.”

VTX SUBCOMPACT

The design went out to tender with three vendors having a serious crack. A JBL design based on VTX A6 subcompact arrays won the day for its combination of price, performance and form factor. The design comprises three arrays of 8 x A6 elements, each with a corresponding hang of three VTX B15 subs (in a cardioid configuration) tucked in behind. The entire front-of-house PA is powered by 5 x Crown I-Tech HD 4x3500W amplifiers, with a sixth in the rack as a hot spare. As many as four A6s can run off a single Crown amp channel, but in this case there are two boxes per channel to provide the necessary gain-shading control.

A number of factors militated in favour of a subcompact line array-based design, such as the VTX A6. First up were sightlines. The theatre has a high rake and truss that can only be raised ‘so’ high. A longer hang would interfere with sightlines to the projection screen. Secondly, with such a steep rake, a minimum number of line array elements would be required for adequate vertical coverage. Again, that would require the minimum complement of boxes to be small enough to avoid sightline interference. Weight was another factor. The truss is hung from a cantilevered section of the grid, lowering the load capacity. The PA couldn’t hog the lion’s share of the load, as capacity needed to be retained for other occasional elements on a needs basis.

“The VTX A6 subcompact system allowed us to keep the hang height short enough to avoid blocking sightlines, keep weight down, while still delivering the required SPL (105dB),” Glenn Thompson summarised. “In the same way, we chose the B15s because of their size and hang height suitability. We wanted to run the subs in a cardioid configuration to keep low frequencies off the stage and push them into the audience area. We installed them in hangs of three, and they’ve been commissioned and tuned accordingly.”