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The Challenge
Groupe Novelty, the systems integrator for the project, was tasked with designing a permanent sound reinforcement system for the cathedral’s daily operations while also preparing it for the large-scale reopening ceremony.
The project required both engineering precision and a highly sensitive approach to the building’s architecture. Strict restrictions were in place throughout the cathedral: no visible cabling, no mounting solutions that could damage the structure, and no interventions that would affect the visual integrity of the interior. Every technical decision had to be coordinated with heritage authorities and restoration architects.
Further challenges included the cathedral’s complex acoustics, limited access, safety protocols related to lead contamination, and a demanding project timeline. The team had to design a sound reinforcement system capable of delivering speech intelligibility and reliable broadcast support in a highly reverberant space, without compromising the perception of the historic interior.
The Solution
From the outset, Groupe Novelty viewed the new infrastructure not simply as a replacement for the previous system, but as a foundation for future services, events and broadcasts. To support this approach, Novelty Paris, a subsidiary of Groupe Novelty, proposed increasing the capacity of the fibre-optic network and building in headroom for future system expansion.
A fibre-optic network with a dual spine-leaf topology was deployed throughout the cathedral, supporting Milan-AVB, Dante and NDI. This architecture enabled the audio and video systems to operate together: Milan-AVB is used to carry audio to the L-Acoustics amplifier network, Dante handles digital audio routing, and NDI provides flexible video distribution to auxiliary monitors and additional zones.
The sound reinforcement system was designed around L-Acoustics and comprises 128 loudspeakers, colour-matched and distributed throughout the cathedral. The installation includes Kiva line source arrays, Syva and Soka column-format loudspeakers, as well as compact coaxial 5XT and X4i systems.
During the design phase, the team used L-Acoustics Soundvision, the company’s 3D sound system modelling software, to calculate loudspeaker placement and achieve even coverage while accounting for the characteristics of the cathedral’s Gothic architecture. The software also helped optimise the system’s performance within the unique acoustic environment of the cathedral.
Particular attention was paid to installation accuracy, including mounting heights, tilt angles and horizontal orientation for each loudspeaker. This was essential to maintain speech intelligibility in a large reverberant volume while preserving the architectural appearance of the cathedral.
The amplification system is built around seven racks, including L-Acoustics LA7.16i and LA2Xi amplified controllers, distributed across the cathedral’s zones. Audio is transmitted over Milan via a Netgear network, ensuring stable system operation and precise synchronisation between the amplified controllers.
At Notre-Dame, the mechanical installation of the equipment was just as demanding as the acoustic design. Since drilling into the stone was prohibited in almost all areas, the team developed mounting solutions that allowed the loudspeakers to be installed without damaging the historic surfaces.
For some positions, a sliding primary support system was used. It was installed in collaboration with the stonemasons — the only specialists authorised to carry out drilling work. This allowed the team to set the final loudspeaker mounting points precisely at the required height.
For the loudspeakers positioned above the capitals, custom metal structures were fabricated. The equipment rested on the stonework, while the cables were routed discreetly through the mortar joints in the columns. For the two Kiva clusters on the galleries, which provide coverage for the crossing, a more conventional suspension method was used, while still remaining visually concealed.
This approach made it possible to integrate a modern sound system into the historic space with great sensitivity, preserving both the system’s audio performance and the visual integrity of the cathedral.
In addition to the loudspeaker system, a key element of the project was the signal infrastructure, designed to support the cathedral’s audio system for daily services while also accommodating external broadcasts.
Audio mixing and signal processing are handled by DiGiCo SD9 consoles and 4REA4 processors. The system is complemented by remote preamps installed close to the signal sources in the choir.
An Optocore fibre-optic loop runs around the perimeter of the building. It is used to capture the sound of the organ and the overall acoustic ambience, as well as to distribute audio signals between the mixing systems and broadcast infrastructure.
A DirectOut Prodigy matrix is used to isolate the digital networks, helping each audio network remain autonomous during external events and remote broadcasts. This is especially important when the cathedral’s permanent system needs to operate alongside external broadcast infrastructure.
Schoeps CCM microphones are used for the lecterns and choir, while Sennheiser MEB 114 microphones are installed at the altar. The Sennheiser Spectera platform was deployed to manage the RF infrastructure.
Sennheiser Spectera made it possible to combine microphone signals, IEM/IFB and control data within a single RF channel. In a historic building where antenna placement and RF cabling are strictly limited, this simplified system deployment, reduced setup time and improved coverage.
Once work on the permanent sound reinforcement system had been completed, the team moved on to preparing for the reopening ceremony — an event of national and international significance.
A temporary audio system was installed for the ceremony. It operated alongside the cathedral’s permanent infrastructure and provided sound reinforcement for the outdoor audience and broadcast coverage.
For the reopening ceremony, the system used L-Acoustics Kara II and X12 loudspeakers. Inside the cathedral, Syva systems were also deployed to support the event.
The reopening ceremony ran without interruption. However, the project’s main achievement was not limited to the successful delivery of a global event. The permanent system continues to operate in the cathedral every day, while systems integrator Novelty Paris remains responsible for its ongoing support, including regular calibration, firmware updates and monitoring of the fibre-optic network.
The Notre-Dame de Paris project received the Inavation Award 2026 in the House of Worship Project of the Year category. The award recognises not only the scale of the ceremony, but also the engineering precision that made it possible.
The project demonstrates how L-Acoustics, DiGiCo and Sennheiser technologies can be deployed in venues where sound quality, reliability, broadcast infrastructure and sensitive integration are equally important. At Notre-Dame, a modern audiovisual system was carefully integrated into the historic space, allowing the cathedral to be heard once again by worshippers, visitors and audiences around the world.
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