Amadeus and Holophonix were called on to design and install a new sound system for the Amphitheatre d’O, part of the Domaine d’O – a Greek-style arts and entertainment site in Montpellier, South of France – with some exacting demands. Because it is an open-air theatre accommodating up to 1,800 people in seating spread across nearly 180°, the project was an exercise directivity control.
The venue hosts four major festivals during the spring and summer, including the Le Printemps des Comédiens theatre festival, Folies d’O musical theatre festival, and the Radio France Occitanie Festival music festival.
Over the past 15 years, the Amphitheatre d’O has used various front-of-house reinforcement systems, from Amadeus, L-Acoustics, d&b audiotechnik, Adamson and others. All were line source designs, arranged in stereo or LCR configurations, and rented during the festival season. As a result, only a few people sitting in the ‘sweet spot’ could hear in stereo during live performances. More than 90 per cent of the audience were subjected to mono sound and comb filtering.
The problems with its sound had prompted the venue’s sound team to look into sound spatialisation systems as a possible solution. Texen, a long-time supplier of technical resources to the Domaine d’O, asked Amadeus and Holophonix to help. The system they devised uses custom sound-ramp speaker modules, each measuring 1,460mm, integrated into the front of the stage with a line of 18 point source C 15 loudspeakers placed above. These are complemented by four cardioid stacks of Diva M? Sub Neo bass units and two stacks of Maestro I infra-subwoofers.
All of the Amadeus speakers are controlled by the newly released Holophonix Ultra processor.
‘We wanted the sound to come from the stage as much as possible,’ says Domaine d’O Technical Director, Nicolas Minssen. ‘We wanted the sound system to “disappear” in terms of perception and location. The main advantages of the Amadeus solution are the precision of the sound, perfect coherence of the sound image for all the spectators, and the aesthetic discretion of the system.’
‘Wherever you are in the amphitheatre, the sound is coming from the stage,’ observes at the Domaine d’O Mixing Engineer, Loic Lambert. ‘It’s a very pleasant sensation; you completely forget about the amplification.
‘The shows we host have not been created using immersive technology, and festival set-up and rehearsal schedules don’t allow any extra time for sound pre-production. It has to work straight away. We ensure backward compatibility. We are always able to broadcast classic console outputs such as the LR and/or the central cluster simulated in a WFS bus, for example.
‘We also work with each show’s operator to prepare the sources pre-routed and pre-positioned in Holophonix, as well as the console configuration so that the switch from stereo to object mixing can be made with two clicks as soon as the operator is ready, without wasting any time,’ he continues. ‘We can easily go from a stereo configuration to an immersive or hybrid configuration. Some people have gone fully immersive from the start, so the console workflow remains the same.’
‘The key part in the system tuning was to get the best uniformity of sound quality across the amphitheatre,’ adds Amadeus Acoustic Engineer, Adrien De Giovanni. ‘This system brings a spatial experience to the Domaine d’O which had never been obtained before while keeping a great sound quality and uniform coverage for all to enjoy this new experience.
‘We’re pushing the C 15 point source loudspeakers to their limits, not in terms of power or SPL, but in terms of low-mid throw. The last row of the audience is almost 35m from the sources. These point-source loudspeakers cannot be placed in a line-source configuration that provides acoustic coupling and longer throw. However, we see an opportunity for improvement in this area, and should have something ready for next season, offered as an upgrade.’
‘The Amadeus speakers combined with the Holophonix solution gave the feeling of hearing the sound coming from the stage – which can’t be obtained using traditional LR or LCR overhung systems,’ says Texen Technical Manager, Antoine Lenfantin. ‘Compared to previous solutions, the physical implementation of the Amadeus system required some adjustments and technical research. These challenges were effectively resolved thanks to close collaboration between the Domaine d’O, Amadeus, and Texen teams. Despite a tight schedule, the training of the Domaine d’O and Texen teams went smoothly, enabling them to quickly adopt the Holophonix technology.’
The design team paid careful attention to the seats positioned close to the front edge of the stage and to the sound ramp speaker modules and those speakers placed at the top of the theatre. Close to the stage – using Holophonix technology – the sound level of each ramp speaker module was adjusted to give the audience the same sound level, clarity, and spatial effect in that lower part of the theatre.
‘For the top seats, the combination of the C 15 speakers with the Diva M2 Sub Neo carried enough punch to get that impact to the last seats without overflowing the lower seats with low-frequency energy. The cardioid configuration of the Diva M2 Sub Neo enabled us to limit the amount of low-frequency energy spilling onto the stage, offering increased acoustic comfort for the performers,’ explains De Giovanni. ‘The eight mighty Maestro I subwoofers have loads of low-frequency extension and energy to cover the audience and proved quite directive, again, keeping the stage completely free from low-frequency sound.’
‘We had to design a sound system suitable for theatrical performances and modern and contemporary musical events,’ says Holophonix Technical Engineer, Francesco Papaleo. ‘Flexibility had to be ensured, as well as unrivalled precision, and the transparency of the sound system.
‘At the very first demo that we organised at Domaine d’O, we shared thoughts and design principles with the local sound team, including sound engineers Loic Lambert and Samuel Pionnier. It didn’t take long to understand the extent of the challenge we were facing, and the multiple constraints that guided the project. But with the objective of a flexible system in mind, we designed one global Holophonix software preset that could be easily and quickly adapted to all the use cases required.
‘The Holophonix configuration fits an “object mixing” approach, taking advantage of the large multi-speaker sound-ramp in the proscenium, the upper arrays of C 15, and the Diva M? Sub Neo. But with only a few clicks in the Holophonix software, the system can adapt for other approaches such as an LCR, or a hybrid LR plus a few other sound objects.’
‘The flexibility of Holophonix helped us to set up the “arc” management of the Diva M? Neo subwoofer line dynamically and quickly,’ says Holophonix Lead Developer, Adrien Zanni. ‘There are two ways to manage ‘arc’ subwoofer set-ups. The subwoofers can be physically positioned at regular intervals in an arc with a fixed radius. In many venues, including at the Domaine d’O, it is difficult or impossible to physically place the subs on a radius.
‘The second way is to place the subwoofers in a straight line at regular intervals. The amount of delay for each loudspeaker is determined by the “arc” parameter, as if the subwoofers were placed in an arc. You can then calculate the amount of delay for each loudspeaker ‘manually’, or using various tools designed by system engineers, and enter each delay value into the output section of the amplifiers. To achieve this, we used the Wave Field Synthesis.
‘Thanks to the Delay Scaling and Gain Scaling parameters offered by WFS, you have an extremely powerful tool for dynamically managing Arc Sub configurations, offering automatic calculation of gains and delays based on the position of the virtual sources. This dynamic subwoofer management provides individual and localised adjustments for each source, ensuring coherence with their real-world positions. This approach, in contrast to traditional mono-based arc set-ups, enables spatial unmasking benefits such as improved summation and timbre. Furthermore, when combined with a main FOH system also driven by WFS, the result is an incredibly convincing full-bandwidth soundfield experience.
In full, the spatial sound system at the Amphitheater d’O comprises 14 Amadeus SR 1460 DO specially-designed sound ramp modules mounted at the front of the stage as a front fill system, 18 Amadeus C15 triaxial loudspeakers flown above the stage, eight Diva M? Neo subwoofers (55Hz to 110Hz) positioned on the technical bridge in a cardioid arrangement as a bass complement, eight Maestro 1 subwoofers (28Hz to 70Hz) positioned on stage to extend the response of the system in the ultra-low end, and eight C 12 R modular stage monitors used primarily as surround loudspeakers.
Explaining the distribution of goals between the Texen, Amadeus, and Holophonix teams, Lenfantin observes: ‘The roles of each partner were well defined, thanks to initial discussions between Texen and the Domaine d’O team, who were looking for a FOH system with low visual impact and offering a true sound image. Working with Gaëtan Byk at Amadeus and Holophonix helped to create a synergy.
‘The technologies deployed for this system received very positive feedback from the operators during the summer season. Loic Lambert and Samuel Pionnier, the Holophonix referral operators, made a major contribution to the success of the project. The success of this experiment paves the way for future projects focusing on spatialised sound, and reinforces the appeal of immersive solutions in live performance.’
‘We have finally succeeded in offering the entire audience an accurate and high-flying listening experience,’ says Texen Director and co-owner, Nicolas Bellino This has been achieved after fifteen years of work in this magnificent venue. I would like to express my sincere thanks to everyone involved in this ambitious project.’
More: http://amadeuslab.com
