A sound ministry in Bloemfontein

Thu, 20 Jun 2013 12:46

The houses of worship market is obviously in a steady state of rising returns given how many massive churches we constantly see upgrading their sound reinforcement systems to the state-of-the-art. Indeed, some of the largest and most sophisticated permanent indoor installations will be found among them and it’s clear to see that fervent church-goers really enjoy the excitement and sheer power of a chest-pounding service. Conceivably, these systems could routinely accommodate the largest bands and services at extreme sound pressure levels with ease.

One network of churches that is on the rise is the International Federation of Christian Churches, formerly known as the International Fellowship of Christian Churches founded in Durban on 18 August, 1985. They are an umbrella organisation for hundreds of formerly independent churches across the country and the globe, including the Christian Revival Church (CRC) in Bloemfontein, led by Pastor At Boshoff. They recently upgraded their own system, supplied by Johannesburg-based L-Acoutics supplier Sound Harmonics directed by owner Joseph Mandy.

The previous system

CRC, had a previous L-Acoustics dV-DOSC system that was in itself quite substantial to service their 5 300 seat sanctuary, including a balcony. The room is large but very wide coming in at around 35m x 100m, which obviously presents certain acoustic problems and coverage challenges.

For starters, the previous system included 18 dV-DOSC boxes; three clusters of six, four dV-Subs; two per side. The dV-DOSC is a dual-8” line source enclosure where the drivers are mounted in a V-shaped configuration and a 1.4” exit titanium diaphragm, neodymium compression HF driver. It has a full range frequency response of 160Hz to 18kHz within a +/3dB tolerance. The dV-Subs are the companion subwoofers for the dV-DOSC line source system and are triple-15” enclosures with a power handling of 1200W RMS and a frequency response of 40 – 200Hz. They have a usable low frequency response of 35Hz (-10dB). Handling front fills, four MTD108As controlled by a MTD108LLCa controller were selected and four MTD115bs controlled by a LLC115b-st controller were positioned for pulpit monitoring.

As far as amplification goes, six LA48a, five LA24a and one LA17a were spec’d and system processing was handled by a DolbyLake processor. So as you can see, the previous system is nothing to sniff at. Nine dV-DOSC boxes a side with four dB-Subs would command almost any large gig, whether indoors or outdoors. The problem faced in the CRC sanctuary, because of its dimensions, is optimal coverage.

The upgrade

To supplement the pre-existing system, an L-Acoustics KARA supplementary system was spec’d. A further 14 KARA boxes; seven per side, were hung alongside two dV-DOSC arrays (nine per array) as in-hangs and a further eight newer model SB118 subwoofers were placed to supplement the existing dV-Subs. Of course, being that the KARA system is newer there were slight tonal differences in the boxes and this was yet another challenge faced by Mandy and his team. He comments: “Because the two PAs overlap quite a bit, to get the delay right between the in-hangs and out-hangs was critical. There is also a clear distinction between the dV-DOSC and the KARA. The client, already a fan of the dV-DOSC, immediately noticed the difference in HF between the systems, because the KARA is a bit smoother. So getting them to match up was a bit tricky.”

A further challenge presented was the fact that because Pastor Boshoff likes his foldback monitoring very loud, the interaction between the MTD115Bs and the original placement of a centre hang was causing some tonality and feedback issues, caused by the proximatey effect of the dV-DOSC centre cluster, located 1.5m from the pulpit. This is why Mandy decided to go with separate, spaced in-and-out hangs. “The original idea for the PA was a left, centre right configuration but due to the high levels the system was being driven, power coming from behind the centre-hang was causing audible stage issues. That is why we decided to go with the four spaced clusters. The end result was remarkably better.”

Putting the larger dV-DOSC arrays on the outsides and the smaller KARA arrays on the insides was also a strategic move, based on the dimensions of the room and therefore the amount of throw required. “The throw from the stage to the back is quite a short throw and on the sides it’s a very long throw. So it made sense having the system configured that way. So now the sound pressure and tonal balance, when you walk around is the same,” says Mandy.

Looking at the L-Acoustics SOUNDVISION 3D model of the coverage pattern in the venue, it is plain to see that from front to back there is only a margin of around three to four dB of difference in SPL. The front seats experience about 103.6dB while the rear seats on the balcony about 99.6dB. The system still has an additional 6dB in headroom (RMS). For powering the KARA system, four L-Acoustics LA8 amplified controllers were installed. These amplifiers have on-board DSP and are networkable which negates the need for a dedicated, outboard controller such as the Dolby Lake.

Front of house also received an upgrade with the installation of an Innovason SY80 digital console fitted with eight-engine FX and 31-band graphic EQ cards. The console can handle 104 channels but only 48 (on stage) were spec’d to cover the needs of the church. Combined with physical inputs, FX and graphic EQ, a total of 72 inputs and 32 outputs are afforded. Lastly, the console is connected to the stage box on the Ethersound protocol on CAT5 cable.

The wrap

Often a supplementary upgrade to an existing system can prove trickier than a ground-up installation. Fitting the new components in with the old presents challenges of tonality while the venue dimensions call for a rethink of the positioning of the arrays. Sound Harmonics clearly had the knowledge and experience to tackle each problem effectively and in conjunction with L-Acoustics SOUNDVISION software, the job was executed successfully and with as much precision as possible. Church-goers at the Christian Revival Church in Bloemfontein will, no doubt, enjoy high-quality sound reproduction for years to come.