JBL's CBT line array columns prove their performance and versatility for live sound as well as installation applications

JBL’s CBT Constant Beamwidth technology really came into its own at the inaugural ‘Sound:Check presents Music for ChildHope’ fundraiser, held recently at St John at Hackney Church, London. All profits from the event, which included a guest appearance by Willie Nelson, went towards helping the work of ChildHope, a charity preventing child abuse and exploitation in Africa, Asia and South America.


The Sound:Check concept itself was created by producer Marie-Claire Denyer and singer-songwriter Stac Dowdeswell. Sound Technology, the Harman Professional distributors, were brought in to boost the technology infrastructure by Kristina Riddington, production manager at KOKO (with whom they have a close relationship). She, in turn, was introduced to the project by One Taste Choir, who have worked at the club.

The task facing Ben Todd from Sound Technology’s Project Team, was to provide even pattern control in a large cavernous, square-shaped church (built to hold 2,000 people) that was “pretty epic in its reverberation time.”

Artists, who were given the opportunity to work alongside the all-female One Taste Choir, a small string section and the church organ, included Zimbabwean born Eska, alternative four-piece group Hejira, Mara Carlyle and special guest Willie Nelson. The choir was led by Sound:Check’s Stac.

Also heavily involved was Eduardo Puhl, one of KOKO’s sound engineers, who mixed the show for the first time through a Soundcraft Si Performer. “The desk was great to work with — very straightforward, with a clear menu,” he appraised.

But the real stars were the JBL CBT column arrays, which reinforced the live acoustic gig. These were chosen not only their pattern control in the difficult space, but also their ability to handle both full range, high power music and speech applications with spectacular levels of fidelity, as Ben Todd recalled.

“St John at Hackney is a particularly difficult acoustic space for intelligibility, with an extremely long and lively reverb. It sounds magical for choirs and so on but for everything else it can be extremely challenging.”

He designed the system with CBT70J+E full-length columns as the main Left/Right front PA, with a further pair of CBT70J delayed just 7.5m down the audience to maintain strong direct to reverberant field ratios throughout.

“Because of the way the CBT’s work, with JBL’s Patented Constant Beamwidth Technology, the 25 vertical coverage combined with 150 degree horizontal of the CBT70 guaranteed a wide coverage beamed narrowly through the audience at ear-height with very consistent frequency behaviour throughout. The advantages brought by CBT's true line-array design ensured minimal changes in direct sound level across the audience area. The system could throw without bouncing excessively off other surfaces, providing a thin wave of unadulterated sound for everyone on axis.”

Four floor-stacked VRX918s subs supplemented the system — augmenting the low end and giving some drama to the performance.


In addition a JBL AC28 was deployed as fill for each of the two balcony levels. Explained Ben Todd, “These balconies have a more controlled acoustic so we went for a nice install speaker.”

Crown XTi 6002 was assigned to drive the FOH system, with an XTI 4002 handling the balcony fills and XTi 2002 the delays — with delay times and tuning set in the amplification’s onboard DSP.

Eduardo Puhl was certainly impressed. “In spite of the church’s natural reverb the CBT’s suited the environment because it was just so directional. The system hardly needed any EQ and I used the Soundcraft preamp’s with condensers, mostly AKG C451s, on almost everything, which was perfect.”

Sound:Check’s Stac Dowdeswell concludes, “We were provided with the most incredible sound for our first Sound:Check event. The design was flawless and met with many a compliment from artists and audience members alike..”

Video: Performance by Stac at the event, with the JBL CBT speakers and PRX monitors visible

For more information regarding Sound:Check please visit http://www.soundcheckchannel.com

For more JBL, Soundcraft and Crown information please contact Sound Technology Ltd on 01462 480000 or visitwww.soundtech.co.uk