Set in the heart of Berlin, St Hedwig’s Cathedral is modelled on Rome’s Pantheon having begun construction in 1747 and opened its doors to worshipers in 1773. In order to preserve its rich history, the cathedral has recently completed an extensive renovation that has seen its entire interior transformed. Part of this transformation is the adoption of a Holoplot X2 Matrix Array system for unobtrusive spoken word reinforcement.
The brief for the publicly funded construction work was exceptionally detailed, with high expectations. The nave has seen significant change, while the original interior layout returns, but now with seating in the round. The aesthetic is clean and simple, with white walls, clean lines and minimal detail – and no concession to visible loudspeakers.
Circular in shape, with a 30m diameter, the central space rises to a dome that peaks at a height of 33m. The huge parabolic space has acoustics suited to live music and to performances from the Klais Opus organ. For spoken word, however, the reverberation times negatively impact intelligibility and pose a considerable challenge.
Sichau & Walter Architects won the redesign contract in 2014, which required an ‘invisible’ solution that would solve these issues while being flexible enough to adapt to the variety of choral, concert and spoken word.
‘Worship architecture fundamentally differs from secular architecture, because its primary purpose is to create a framework, so that the celebrant, in this case the priest, can deliver mass in a way that offers worshipers a religious experience,’ says Founding Partner, Peter Sichau. ‘Our methodology required the architecture and the space to be recognisable solely by the atmosphere and the acoustic, which is very complex and challenging in this case.’
The Holoplot team modelled various design options to meet this exacting brief. Jakob Greif, Holoplot Applications Engineer and technical lead for the project, describes the final system design as a ‘true example’ of working with a building to achieve the very best for the whole community.
‘Circular buildings are not new to Holoplot, but the difference here was the position of the altar and therefore main microphone positions,’ he says. ‘Having spoken word coming from the centre of the space, with the audience in-the-round and no possibility of adding localised loudspeakers, created a unique situation we had to try and solve.’
To address the space’s positional challenges and 6.5s reverberation time, Greif and the Holoplot team designed a system based on the X2 Matrix Array.
X2 is Holoplot’s compact Matrix Array loudspeaker, equipped with Power-over-Ethernet, enabling it to receive audio and control signals, and power through a single cable, simplifying installation and, in combination with the unit’s slim profile, enabling flush mounting. These features allow the arrays to disappear behind custom screens, in narrow, recessed wall cavities, so as to not interfere with the building’s lines.
X2’s size and rotation flexibility enabled the team to use the modules in a variety of positions, including fixed in portrait orientation behind the main columns. 3D Audio-Beamforning then solved the positional issues created by having the altar located centrally.
‘We have hidden 22 MD30 units behind perforated panels,’ Greif continues. ‘The arrays are fixed in only three locations and deliver unique coverage zones that disregard the highly reflective surfaces of the cathedral. 3D Audio-Beamforming and our optimisation algorithms not only allow us to create a circular, rounded beam but also to split the direct throw, avoiding the altar microphone in the centre of the nave and raising the gain before feedback threshold.’
‘Our priests will finally be able to speak comfortably at the altar and that is possible thanks to the way Holoplot has designed the active beams,’ notes Johannes Rogge, Technical & Media Integration Lead for the St Hedwig project. ‘I am really impressed by how that works – to be able to hear the difference just by moving a few meters, is amazing.’
Thanks to increased sound control in both the horizontal and vertical axes, ensuring that sound does not hit the highly reverberant walls, diluting the clarity of speech, the team was able to build on these positive results to offer the cathedral committee a range of functions, increasing flexibility, usability and, importantly, promoting creativity in the space.
‘The technical team for the cathedral is staffed by volunteers, so it was essential to provide a system that was not intimidating to use,’ says Greif. ‘We have created a range of different presets that can be accessed to support any type of performance, as well as supporting the priest delivering mass or sermons. We also included a preset for exciting the nave’s natural acoustic which will give a much more musical result, elevating the spiritual feel of a choral performance. The result is something we are really proud of, and we hope the community of Berlin will be proud of it, too.’
The process has left a lasting impression not only on the people of St Hedwig’s but also on the team from Sichau & Walter Architects. ‘Based on this experience, Holoplot is the only system that can be used for such tasks in the future,’ Peter Sichau concludes. ‘No other system that I know allows for massive spatial impression or the specific adjustment of acoustic subtleties.’
More: http://holoplot.com
