Renkus-Heinz UBX Loudspeakers Restore Clarity to Historic London Cathedral
A discreet audio system upgrade at Saint Sophia’s Greek Orthodox Cathedral, London transforms speech intelligibility.
Saint Sophia’s Greek Orthodox Cathedral, also known as the Cathedral of Divine Wisdom, stands in the district of West London. While the cathedral’s domed roof and arched windows draws hundreds of visitors each week, its original sound system was no longer fit for purpose. Renkus-Heinz UBX16 loudspeakers were installed to modernize the cathedral.
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Week after week, congregants reported difficulty hearing clearly. While it could provide low-level background music for visitors during the day, the system performed poorly when used for speech during services, producing muddy and unintelligible results. System integrators API Sound & Visual, who specialize in the design and installation of AV systems for houses of worship, heritage buildings, community spaces, and commercial buildings, worked closely with distributors CUK Group to start from scratch and design a new, dedicated speech system that delivers clarity from front to back, while respecting the space and its architectural limitations.
Stephen Neath, sales director at API Sound & Visual, explained that in a space of the scale of Saint Sophia’s Greek Orthodox Cathedral, dominated by hard marble surfaces, sound reflects endlessly. "It was imperative that the system was highly directional, focusing audio precisely where people are seated; otherwise, the spoken word would simply be lost,” he said.
To meet these goals, two Renkus-Heinz UBX16 loudspeakers were installed as the main left and right sources, chosen for their precise vertical pattern control. Their beams were aimed to cross approximately two-thirds of the way down the nave to provide primary coverage. To ensure even horizontal dispersion, two powerful but compact UBX8 loudspeakers were positioned on the left and right sides and aimed outward. An additional pair of UBX8s was installed further down the room at the sides as delay fills, reinforcing the main system and maintaining clarity and level consistency for attendees towards the rear.
Guided by CUK Group, compact Powersoft amplification was specified to pair effectively with the loudspeakers, enabling a tidy rack installation while providing greater flexibility for system tuning and overall performance. Control is handled via a single-button wall panel with a small display, allowing preset “scenes” to be selected so the system is automatically configured. This ensures that, during services, staff can focus entirely on worship.
“API approached us for design ideas in this unique space,” explained James Lawford, live sound channel manager at CUK Group. “We carried out a 2D direct sound simulation using EASE Focus to check coverage and dispersion from the main loudspeakers. This allowed us to confirm the placement of the delays and ensure the system would cover the entire space.”
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Prior to installation, a system demonstration was held for key cathedral staff, allowing them to hear the results first-hand. “The difference was immediately obvious,” added Neath. “The new system was a million times better than what they were used to.”
The cathedral’s extensive marble surfaces meant direct drilling was not an option. The previous system had been mounted using wooden backings fixed into the grout rather than the marble itself, and this approach was carefully reused for the new installation. Another challenge presented by the marble was in cabling, however, the installation progressed smoothly overall. The loudspeakers’ black casing also helped blend discreetly with the cathedral’s detailing, minimizing overall visual impact and preserving the unique aesthetics.
Where complaints about poor audibility had once been a weekly occurrence, the response has since been overwhelmingly positive, with worshippers able to hear clearly throughout the space, without compromising its historic character.
“The project is a credit to API’s careful installation process, and the predictable, high-quality results that can be achieved using Renkus-Heinz UBX Series loudspeakers, even in highly reverberant environments,” concluded Lawford. The result is a system that finally allows the spoken word to be heard as intended, restoring clarity, enhancing engagement, and ensuring the cathedral can continue to serve its community with confidence.

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