The interior of St. Pius X, the largest Catholic basilica in Europe, which now sports an audio systsem with Crown XTi 2000 and CTs 1200 amplifiers. Lourdes, France (September 24, 2007)–Audiomaster of Pau, France, recently completed an upgrade of the existing sound system at the Basilica of St. Pius X in Lourdes, which included 17 Crown XTi 2000 and four CTs 2000 power amplifiers.
St. Pius X, the largest Catholic basilica in Europe, is a modern concrete building that is almost entirely underground, spawning its widespread nickname as the ‘Underground Basilica’. Construction of the facility was completed in 1958 in order to accommodate the enormous crowds that would be making a pilgrimage to Lourdes for the centenary of the Apparitions, the 18 visions of the Virgin Mary by Saint Bernadette.
Designed by French architect Pierre Vago, the oval structure is 625 feet long by 200 feet wide with sides that slope gradually upwards from the sanctuary in the center. With a ceiling supported by 58 concrete pillars and 29 concrete beams, the basilica has certainly served its purpose in welcoming large numbers of visitors, simultaneous accommodating as many as 25,000 people within its nearly 130,000 square-foot space.
As one can imagine, a structure composed almost entirely of bare, solid concrete creates a poor acoustic environment and the basilica had been in need of an audio upgrade for some time. Prior acoustical research showed that the congregants were in the indirect sound field after 65 feet – a condition less than optimal. Despite the many speakers that had previously been installed, sound in many parts of the structure was often fuzzy and indistinct, making it difficult for parishioners to follow and participate in the ceremony.
After performing considerable acoustical modeling, Francis Larriau of Audiomaster chose to implement a Harman Professional audio solution in which Crown XTi 2000s now amplify JBL VRX Series constant curvature line arrays (in passive mode), which are hung in clusters of two to four speakers to cover the central part of the basilica. The VRX arrays were chosen for their power, compact size, light weight and flexibility while the XTi amplifiers were selected for their ability to drive the speakers to their full performance safely and without distortion. The crossovers for speakers, while capable of being done in XTi, were implemented within the VRX boxes themselves.
Reinforcing the periphery of the basilica are 30 JBL JRX112Mi two-way speaker systems powered by the Crown CTs 1200s. There is also a small area for choir and organ rehearsals that is covered by four of the JRX112Mi.
Spread out throughout the facility are a dozen interconnect boxes that allow signals to be routed to and from the control room. The boxes support multiple formats: digital over fiber, RF modulation, networked audio, and analog audio.
The constraints put on the new system were fairly stringent. The architecture required as much as possible to be concealed without having to modify the existing concrete. Furthermore, the original RT60 decay was timed at 17 seconds at 350Hz. This time was effectively reduced to 10 seconds following the installation.