The Perfecting Church in Longdale, Johannesburg, like any other large scale church, has very specific audio requirements to meet the demands of its massive 4 000-seater sanctuary. The sanctuary itself is about 70 metres wide so the challenges presented when installing a sound system is myriad, the main focuses of course being coverage, high quality sound reinforcement and not to mention a console that is fairly easy to use.

Long-time industry stalwarts Tadco were called upon to provide audio installation services to the Perfecting Church sanctuary. Perry Elias and Josh Oates were kind enough to meet me there to discuss the installation of the Nexo Geo S1210 and Digico SD9 system that was selected.
“The whole dive here is to get them into a fully digital domain using MADI streams because,’ Perry comments, “it interfaces to almost any pro kit with a MADI interface. It’s two BNC cables and Bob’s your uncle.’


Hardware

Starting with the console, a Digico SD9 was selected for its comprehensive feature set, digital processing and preferred MADI compatibility. The church’s on-stage setup requires a minimum of 24 channels, making the SD9 the logical choice since it is medium format and supports 48 inputs of what Digico calls Flexi Channels (mono or stereo). This also leaves room for expansion if they ever do need additional channels.
A 32-channel D-Rack was then employed, which is a 32×16 remote box connected via CAT5 cable, utilising the MADI protocol to and from the console. The microphone snake from the stage is split via three Klark Teknik Square 1 splitters for FOH and monitoring to a Yamaha M7, which feeds a combination of Nexo PS15 and LAX wedges (for the vocals) on stage.

The loudspeaker system selected for the sanctuary is a Nexo Geo S1210 line array. Nexo has a fantastic reputation worldwide for delivering rock solid performance, reliability and utmost audio quality. Indeed, their Alpha systems are legendary and many live music venues would not have fared the same without them. Quite simply, they are warm, inviting speakers that are comfortable to listen to in almost any application.

For the main FOH system, four arrays were flown to achieve maximum coverage. Each side therefore garnered two arrays; an outer with six S1210s and an inner with three S1210s. The purpose of this configuration was to supply centre – fill from the two inner arrays on a centre bus and a left and right bus for the outer arrays, giving absolute control of each specific coverage zone’s levels.
For the outer arrays the 120 degree non-coupling waveguide configuration was selected to properly cover what is an extremely wide sanctuary, measuring in at around 70 metres. However, the width of the room was not the only obstacle.
Perry explains: “It was quite challenging installing this line array because the room is not perfectly symmetrical. It looks symmetrical but it’s not. The software measurements just gave us a guideline but you need to practice some common sense. Nothing beats your ears.’

For low-end reinforcement, four Nexo Alpha S2 subwoofers were employed; two of each per side. Granted, these are now older-model subwoofers in the Nexo line but there is no doubting the quality and low frequency extension of these dual-18′ enclosures. After all, with a peak SPL of 140dB and a frequency response of 32 to 64Hz, they are a pretty good match for the S1210s which extend from 19kHz down to 53Hz.

In any case, the S2s are only biding time until phase two of the installation, set to go ahead later in 2013, where four brand new Nexo RS15 subwoofers will replace them. The RS15s extend from 200Hz to 35Hz in omni or 150Hz to 35Hz in directional mode, therefore giving a wider range of crossover options. They have a peak SPL of around 139dB which is quite similar performance to the S2s.

Powering the main system comes courtesy of only two Nexo NXAMP 4×4 DSP-loaded amplifiers, which are among some of the most powerful the industry has to offer. In a nutshell, these amplifiers can drive a maximum 8 000W per side in a stereo setup (16 000W total) all the way down to 2Ohms, incorporating two dual-core 24-bit fix point DSP chips with 56-bit accumulators for system processing. There are a variety of configurations that can be selected because these are essentially four in/four out amplifiers but in the case of Tadco at the Perfecting Church, one NXAMP was selected to drive the S2 subs and another to drive the main arrays in LCR configuration.

For monitoring a variety of high quality amplifiers were employed. For the LAX vocal monitors, an LAX MPA4450 was the logical choice and for the other two LAX monitors, a Behringer EP1500. Two Crown Macrotech 3600VZs – each with their own Nexo PS15 TD controller – run the pastor’s dual Nexo PS15s and the keyboard/organ monitors in stereo.


Walkaround

After the gist of the system had been revealed to me I was played a selection of modern gospel music at a level that was typical of a service. Immediately I was met with the warm, inviting sound that Nexo has become known for. The low end extension of the system really presented itself strongly, but not in an obtrusive way. Rather, it was full and commanding with the impression that it could pound the chest if need be. The mid-range was smooth, too, and there were very little spectral artefacts that caused my ears to prick. This mated very nicely with the top end, which was crisp and shiny and seemed to ’glow’ from the four arrays.

Gathering my initial impressions, I set out to listen to the coverage consistency of the system. I made my rounds, listening for dropouts, phase seams and spectral issues. Indeed the low end coverage of the system was very consistent and I could feel the bass nicely from end to end of the sanctuary. The spectral consistency was also very good but I did notice a slight increase in volume when I arrived at around 60 degrees off-axis due to the larger arrays being orientated there, but this is expected if you’re sitting directly in front of them. Travelling to the outer extremes to around 120 degrees off axis, the volume dropped off again but I expected as much because these seats are pretty far behind the front of the stage at that point. These are the challenges a very wide room presents. Otherwise I found that the system was set up as well as one could ask for in a room such as this and Tadco, Perry and his team had clearly done a fantastic job in rigging and configuring the system.

by Greg Bester