With soaring ceilings, cavernous naves, and smooth surfaces of stone or stained glass, cathedrals can present unique acoustics challenges. St. John's Cathedral in Brisbane, Australia is no exception, having been bestowed the distinction of having one of the longest reverb times for a chapel in the southern hemisphere, ringing in at a whopping 7.2 seconds—delightful for Gregorian chants or pealing bells, but a sound reinforcement conundrum. The solution was an L-Acoustics distributed 5XT system, installed in November 2017, which has since been providing the congregation with crystal-clear audio at the renowned Brisbane landmark, while preserving the architectural integrity and beauty of the heritage-listed structure.
St John’s Cathedral is the mother church of the Diocese of Brisbane, which was created in 1859. Built as a mixture of French and English Victorian Gothic Revival styles, it boasts the only fully stone-vaulted ceiling in Australia. Adding to the reflective surfaces, the cathedral's internal walls are built of sandstone from Helidon, west of Brisbane.
“The interior is long and has some very excitable frequencies that occur in the strangest of places. It is stone-vaulted and there is nothing anywhere to absorb or diffuse the sound other than people and some timber carving,” explains Project Manager Gerry Gavros.
“The new system also had to cater for the many different modes they run the cathedral in, with various congregation sizes and seating locations and orientations,” adds Gavros. “There are side chapels, altar areas, choir stalls, etc. All get used at different times for different applications. It is a very busy place throughout the week.”
Don Bowden, Director of DBAV Productions, the church's long-time technical integrator, created the initial solution design concept using an L-Acoustics ultra-compact 5XT system, which catered to St. John Cathedral's budget and schedule constraints.
With the help of Dan Fittell at Brisbane Sound Group, the 5XT system was first tested in a temporary installation inside the cathedral as proof of concept.
“It was proved that a distributed system running at lower controlled levels minimised the amount of energy that emanated into the cathedral’s domed roof structure,” comments Gavros.“The result was exceptional. Congregation members said that this was the first time they had heard the full service clearly in over 10 years. It was enough for the Committee to proceed with the purchase.”
The final design was verified using Soundvision, L‑Acoustics 3D simulation programme before proceeding with the installation, which needed to be completed within a very strict one-month period to accommodate an important service. To expedite the process, the system was pre-cabled at the beginning of the installation period allowing the permanent system to be swapped for the temporary one within the space of just a week.
Adding to the challenge, the church is heritage-listed and the 5XT cabinets could not be fixed into the sandstone columns. Instead, Fittell designed a bracket using tensioned stainless-steel wire system to mount the speakers. In total, 44 5XT enclosures RAL colour-matched to blend with the walls, four in the standard colour, and five LA4X Amplified Controllers were installed throughout the cathedral.
The Very Rev’d Dr Peter Catt, Dean of Brisbane, is very happy with the new sound system. “The sound is very clear, and members of our regular congregation have commented that they now can hear every word spoken at the services and in the sermons, making their experience at church much more enjoyable,” he says. “The quality of sound for concerts and events held in the cathedral is also of a very high standard. We are very pleased with our new sound system.”