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Bath City Church

The recent upgrade to the audio infrastructure in the historic Bath City Church posed a number of design and engineering challenges, all of which were met by the Autograph Sales & Installations team.

Bath City Church is located within The Forum, a beautiful art deco former cinema which originally opened in 1934 and was one of the last to be built specifically for the era of silent movies. With a capacity of 1600, the building is now a contemporary worship location that also provides conference and concert facilities. The project’s goal was to update the installed audio systems such that they could handle the very diverse religious activities of the church, and also make the location more attractive to potential hire clients for other meetings and events.

Autograph were awarded the contract to design and supply a new loudspeaker system, amplifiers, mixing console, cabling and ancillary items, as well as to supervise the engineering services required. The existing front of house mixing position needed to be moved to a more suitable location which necessitated the construction of a new riser and surround enclosure to accommodate it. Autograph appointed a preferred sub-contractor for this part of the works, a specialist construction company whose expertise lies in listed buildings and worship sites.

The entire install hinges on digital networking, from the desk outputs onwards everything is Dante

The new loudspeaker system also required new flying points to locate it correctly, and holes were cut in the plaster ceiling to allow the chains to pass through from their secure points in the roof space. The system can be removed when necessary by accessing the chain hoists in the roof space from a walkway.

Autograph specified the new EM Acoustics Halo-C compact line-array loudspeaker system. Project manager Chris Austin said, ‘Like most rooms originally designed to deliver sound to a large audience without amplification, The Forum presented real challenges when designing and installing a sound reinforcement system. Fortunately we’ve worked in numerous locations of this kind previously, and we found Halo-C to be the perfect choice for the project, and not just because of its outstanding acoustic performance - its small size allows a powerful system to be very unobtrusive, and its accuracy allowed us to achieve a very tightly-defined coverage right across the stalls. It is also remarkably cost-effective, as up to sixteen cabinets can be powered from a single amplifier‘.

He continued, ‘We specified Lab Gruppen PLM-series amplifiers not only because of their reliability and audio performance but also because of their onboard processing and Dante compatibility, which made a huge difference to the cabling infrastructure. A single PLM10000 is located in the roof space and this powers all the Halo-C mid / high enclosures, while another lives in a side-stage rack (with a Lake LM-44 and the DiGiCo D-Rack), powering all the EMS-51 front fills which are attached to the stage lip using brackets custom-made by Autograph. Using Dante allowed us to locate the amps closer to the loudspeakers, thus reducing the cost of the project even further as there was less requirement for copper cabling.’

Mixing the meeting on the Digico SD9

The mixing console of choice was a DiGiCo SD9, supplied with a D-Rack, which also contributed to the control of project costs - Chris explains: ‘Using the DiGiCo D-Rack gave us the option of moving all the audio signals around the room via inexpensive CAT5 cable rather than expensive copper multicore. In fact the entire install hinges on digital networking, since from the desk outputs onwards everything is Dante with the processing being in either a Lake LM44 (for the under-balcony speakers and outer zone PA systems) or a Lab Gruppen PLM 10000Q amplifier’.

‘After a tender process to narrow it down to two possible suppliers, we went in to demo the full system during a weekend. We later went back to try out some alternative subwoofer locations because the room is extremely absorptive of low frequencies. We eventually settled on a centrally-located end-fired setup which will be further refined in due course, as we believe we can further improve the low-frequency coverage. The new system provides seamless coverage of the stalls as specified, but we also designed-in a future fit option for the balcony. During commissioning we brought in additional EM Halo-Compact loudspeakers to create pre-sets for an expanded system, so extra modules can be easily integrated with the installed system if necessary, without the need for re-tuning’.

Chris concluded, ‘In common with many projects of this kind we spent a lot of design and engineering time in reconfiguring and re-using as much of the existing equipment as we could - for example, we relocated the existing mains power supply and analogue multicore to the new mix position and kept the existing under-balcony speakers, just updating their power to new Lab Gruppen E-Series units. This helps to keep the overall project costs down of course, and by carefully combining new and existing items we managed to produce a fully integrated system that suits the venue and the intended applications perfectly’.


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