The acoustic conditions for an acceptable sound were anything but ideal. Flutter echoes and standing waves caused by the unforgiving concrete and parallel walls throughout initially made it impossible to produce a powerful and well-defined sound source. Laying a sound-absorbing special carpet and the careful use of acoustic panels in the passageways between the three large event zones quickly enabled Grotegeers to get around the problems without seeing costs go through the roof.
While the so-called 'Main' zone with its large dance floor hosts the actual discotheque and gigs at the weekends, the DON also has a smart 'Bistro' featuring a long, friendly bar, and the 'Club', with a smaller dance floor, that can also host corporate events or birthday celebrations. Sound for each of the three event zones can be supplied independently, or jointly from any of the other zones. Audio signals can also be routed from anywhere into the entrance foyer and to speakers located in the WCs.
All the routing and loudspeaker control is performed using a single Yamaha DME24N. The engine has a total of four stereo inputs coming from the three DJ mixers in the respective event zones ('Main', 'Club' and 'Bistro') and the Bistro CD player. Inside the DME the freshly digitised input signals are routed to a switchable digital matrix, from where they are distributed to crossovers and propagation delays, converted back at the outputs and transmitted via the Yamaha power amplifiers to the loudspeaker systems.
Amplification in the 'Main' zone is handled by a Yamaha P7000S amp, which provides power to four VMB Pro-208 speaker cabinets, and a P5000S amp that looks after a couple more Pro-208s. A Crest CA12 power amplifier drives a VMB 218-C2 subwoofer (2x18'') and two VMB 215-C2 subs (both 2x 15'').
The subwoofers in the 'Club' - two VMB 218-C2 systems - are driven by a second Yamaha 7000S amp, while as in 'Main', the four primary speakers in the 'Club' (also VMB Pro 208s) are linked to a Yamaha P5000S.
A 100V PA-4240 power amplifier also drives the T+M speakers that provide background music in the 'Bistro', the WCs, the large 'Main' bar and the entrance foyer.
The system was installed by light and sound specialists Pan Music from the neighbouring town of Lohne.