Located in the Maltese town of Mosta, the Mosta Rotunda is a 19th century circular neoclassical church with a 37m diameter dome, inspired by the Pantheon in Rome – the third largest unsupported Church dome in the world. Today, it is not only a place of worship but also a popular tourist attraction with stunning architecture and rich history.
Recently, the RCF Engineering Support Group collaborated with local distributor The Sound System Co Ltd in the installation of a sound system designed to reduce room reflections that were compromising speech intelligibility. The chosen solution was RCF’s digitally controlled VSA column array.
The installation comprises eight microphones connected to an RCF M18 digital mixer, two RCF VSA active steerable columns and in fill loudspeakers. The team worked to ensure even intelligibility across the seating area, despite the reverberation caused by the church’s architecture.
This system relies on DSP to direct the audio signal of each loudspeaker towards the listening area. The VSA column array is a multi-amplified vertically steerable array, which means that each individual speaker is separately amplified and digitally controlled, so the sound can be vertically tilted without inclining the cabinet. Additionally, it is fully compatible with RDNet, proprietary RCF management software. The installation includes a main VSA 2050 II directed into the far field, mounted on top of a VSA 1250 II used as a down fill. Both arrays are mounted on the wall.
‘We started by acquiring far-field STIPA measurements and optimised VSA 2050 II beaming and tilting by accessing the speaker configuration, using an RCF Control2 interface and RDNet software,’ says RCF ESG, System Engineer, Francesco Venturi.
Once the beaming preset was determined, the team performed FFT measurements to acquire transfer functions magnitude plots to tune VSA 2050 II frequency response to the church acoustics.
‘We shaped VSA 2050 II response by acting on the DSP parametric equaliser, using RDNet software,’ Venturi continues. ‘The process was then repeated for the near field VSA 1250 II steerable array, first configuring the beaming preset, then optimising the response.’
After tuning, the loudspeaker system was able to provide accurate voice reproduction with an even intelligibility figure above 0.50 (in the empty church). The RCF M18 digital mixer allowed optimisation for each microphone for gain, gate and EQ settings.
‘The improvement in intelligibility with the RCF steerable array system is truly remarkable,’ reports Jon Vella Zarb of The Sound System Co Ltd. Locally, the church is notorious for its poor acoustics – RCF rose to the challenge and the VSA system truly exceeded my expectations, providing excellent audio for the Mosta’s congregation.’
More: www.rcf.it
