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Chaillot National Theatre in Paris adopts 3D sound

Amadeus, Solid State Logic (SSL), Lab.gruppen and Sonic Emotion worked on the project together

French speaker manufacturer Amadeus has installed a ‘3D Sound’ system within the Chaillot National Theatre in Paris.

Along with Solid State Logic (SSL), Lab.gruppen and Sonic Emotion, the four companies joined forces to design a one-of-a-kind electro-acoustic sound reinforcement system for the theatre.

As the system in the 1270 capacity Jean Vilar hall was due to be replaced, Amadeus implemented Wave Field Synthesis (WFS) technology.

Explains Marc Piera, Chaillot National Theatre’s sound department manager: “I personally consider that the systems using a single-dimension speaker network, like line arrays, are inept for sound reinforcement in most theatre buildings. These systems were primarily designed for open field concerts, where the audience area is very wide and very deep, and most of the time, on a flat or lightly sloped ground. They create a uniform sound pressure field, but most often they degrade the sound image for most of the audience.”

He adds: “The Jean Vilas hall’s intrinsic technical, acoustical, physical and mechanical properties led us to prefer an original sound reinforcement system, based on a ‘holophonic’ concept. Listening conditions are thus identical for all spectators, wherever they are in the hall.”

The theatre’s technical manager, Denis Desanglois, says: “We wished to abandon the stereophonic paradigm, the line array-type. So we implemented a WFS-based system prototype and asked the companies we were working with for their feedback,” explains Desanglois. “Some technicians were totally initially disoriented, but eventually everyone was happy, technicians and artists alike. The sensations of listening are completely different, wherever you are in the hall, you experience the same sound, that’s pretty amazing. We even integrated a 24-speaker ramp in the front end of the stage, to avoid the usual ‘sound hole’ first row of seats!”

The idea of Wave Field Synthesis was developed in the Netherlands in the 1980s by the Delft University of Technology. WFS concept makes it possible to synthesise “sound holograms” by simulating acoustic waves produced by virtual sound sources. To do this, the system uses a large number of loudspeakers, regularly spaced and used conjointly. They are each controlled with a delay and a gain to form a wave that emanates from the desired location of the virtual source. This process is repeated for each sound source in the sound scene.

Michel Deluc, Amadeus’ R&D manager, continues: “ We worked with the Institut de Recherche et Coordination Acoustique/Musique, to develop the multichannel sound spatialisation equipment used in their Espace de Projection. This led us to develop and install 339 custom-made loudspeakers. Transposing this technology for the Chaillot National Theatre, allows large audiences to experience it…”

A first line of passive coaxial loudspeakers has been integrated in the front edge of the stage. These 24 loudspeakers, variants of Amadeus PMX 4 model, form a large-scale ‘sound bar’.

The second line of loudspeakers is made of 11 Amadeus UDX 15 active coaxial speakers, with remote bi-amplification. This line covers the first two thirds of the bleachers. A third line is made of 11 Amadeus UDX 12 active coaxial speakers with remote bi-amplification. A fourth ‘Surround’ line is made of 6 Amadeus UDX 12 active coaxial speakers, with remote bi-amplification. A unique bass reinforcement system is set up on lateral first level technical bridges, on left and right-hand sides. It is made of six Amadeus MAESTRO subwoofers, each hosting two long-excursion speakers, loaded by a folded hyperbolic horn.

This sound system is completed with an SSL Live L300 digital mixing console (pictured), used with two Network I/O SB 8.8 (8 analogue I/O each) and two Network I/O SB i16 (16 analogue inputs each) Dante stageboxes.

Philippe Guerinet, director of international sales for SSL and SSL France manager comments: “Audio over IP allows us to put the stageboxes where needed, with minimal and redundant cabling, and to connect on the network all kinds of Dante-enabled gear: Amadeus sound reinforcement system, SSL L300 console, SSL Network I/O stageboxes, and every other ancillary equipment needed. This network approach notably allows us to solve classic problems, like signal distribution without adding any TDM routers; there’s no loss, either noise induced in the audio signals, and latency is particularly low.”

Second picture: The outside of theatre. Credit: Peet-Simard