During recent refurbishments, between 2004 and 2007, a completely new ventilation system was installed, the chairs on the ground floor and first floor were replaced, and on other floors they were repaired and the walls were painted in a different colour. The theatre was partially re-equipped with some new audio and video elements, and an Ethernet ring added, as well as new loudspeaker and light cabling. However no changes were made to the acoustics and no new public address installation was planned.
In 2009 discussions began between Dirk Minnebo, (head of sound at Vlaamse), the technical support department of d&b audiotechnik, and Amptec - the Belgium distributor for d&b, regarding a new PA system for the venue. An acoustic simulation was carried out to determine whether a left/right system or a central mono cluster would be appropriate. A L/R system was quickly rejected, not only for practical reasons but because the sound dispersion of a central cluster is more effective for evenly dispersed sound across the short throw, tight arc of the auditorium. A centre cluster also avoids the problem of high sound pressure levels as would occur at the seats nearest the L/R clusters.
A simulation for a line array system as well as for a conventional point-source system was made in the central position. The vertical dispersion angle needed to reach the centre of the ground floor up to the last rows of the uppermost balcony is very wide. This precluded a line array, as such a vertical dispersion angle would need a line array far too long to be aesthetically approved by the venue.
On recommendation from Amptec, with the design confirmed by d&b technical support, a centre cluster of four d&b Q10s was proposed. With their dispersion of 110°h x 45°v these cabinets would not only achieve the requisite vertical dispersion but would also create sufficient horizontal dispersion for the front boxes. The added benefit of horizontal dispersion control down to 400 Hz, thanks to the position of the 10" speakers within the Q10 cabinets, confirmed the efficiency of the proposed design.
From a technical point of view the installation was limited by one factor; it was very difficult to install a delay system on the fourth balcony due to architectural considerations (the Vlaamse Opera is classified as a 'heritage' monument). However, the upper top cabinet of the central clusters could be aligned to take this role without compromising the rest of the sound field.
For the distribution on the ground floor, the position of loudspeakers was crucial to obtain optimal audience listening results, yet here the auditorium décor is at its most elaborate. Amptec resolved a mechanical solution using custom designed stand-off mountings for the d&b Q7 (75°h x 45°v), placing them in front of the gold-plated filigree frames that adorn the walls at the ideal loudspeaker locations. This mounting system is further enhanced by being both rigid for purpose, yet easily de-mounted; so the loudspeakers and apparatus can be quickly stowed away in the loges when reinforcement is not required for performance.
Away from the centre system only a very small amount of fill coverage is required, and only on the ground floor to the far left and right side on the first rows of the theatre. One horizontally mounted E8 to each side suffices. Surround sound in the auditorium is from wall mounted E0s, and low end of Wagnerian proportions is delivered by the discreet placement of single d&b J-SUBs in each of the technical loges. Amptec supplied a mobile set o
