Commissioned by the cathedral to help recreate the sound of the organ in the challenging acoustical space, Major Tom Limited was clear that the sound had to be powerful and accurate, and the various audio elements had to be perceived in the same way at various points throughout the building, and particularly in the choir.
"Before the organ repairs commenced, we came in one night with our Meyer Sound SIM 3 audio analyser and eight microphones," says Chris Marsh of Major Tom Limited. "We took measurements at locations from the conductor's position in the quire, in the north and south transepts, and in the nave, where the congregation sits. We discovered that the full range organ sound carries convincingly into the nave without being deafening at the source, and also that one organ note generated many strong harmonics from the other pipes and the building acoustics."
Further complicating the task was the fact that the organ was really two complex instruments, facing each other across the quire, with the swell and choir organs to the south and the great and pedal organs to the north.
Marsh set out to design a system with loudspeakers that would throw in the same direction as the organ pipes, using the building to the same acoustic effect. He also knew it was important to utilise several loudspeakers to prevent overloading of drivers when the organist built huge chords. This requirement raised limited space and aesthetic concerns. "The cathedral is a renowned tourist destination, so we had to keep the system very discreet," notes Marsh. "And there was certainly no place to put amplifier racks."
With help from the MAPP Online Pro acoustical prediction programme, Marsh fashioned two complementary self-powered loudspeaker systems. For the choir and swell organ he employed four UPA-1P loudspeakers and dual 500-HP subwoofers. The great organ was looked after by dual MIca line array loudspeakers while the pedal organ was covered by two UPA-1P loudspeakers paired with two 700-HP subwoofers. Matrixing and equalization were supplied by a Galileo loudspeaker management system with two Galileo 616 processors.
For the organ sounds, the temporary instrument used high-resolution samples from the Hauptwerk virtual instrument software application by Milan Digital Audio. The organ was played using a custom-made, four-tiered keyboard with a full pedalboard; the instrument's 'virtual stops' were controlled using dual 17-inch touchscreens.
The sound produced by the system quickly earned praise from the cathedral's music department. "Wow, what a big beautiful sound. I'm speechless," was the reaction of Sound Supervisor Kevin Skelding.
(Jim Evans)
