With the new festival season fast approaching, in a country noted for its outdoor events, if the new proposals become law it will have a major impact on festival promoters and production companies. Thus FACE decided it was time to act.
By chance the Belgian distributors had carried out measurement tests of Martin Audio's new Multi-Cellular Loudspeaker Array (MLA) nine months earlier - during an Amnesty International concert in Antwerp's Groenplaats - followed by a demo at the large Antwerp Sportpaleis arena. And they knew the system would meet the new criteria.
"The results were simply staggering," said de Piere. "From the outside, the MLA enclosures look like ordinary loudspeakers - but they conceal an ingenious design philosophy."
The MLA was designed to minimise the variations in frequency response and sound pressure levels - effective over distances of up to 150m. Thanks to an accurate predictive analysis, trial-and-error array design has been replaced with intelligent numerical optimisation of the array's output based on a highly accurate acoustic model. With the multi-cellular approach, each cell is individually addressed by its own DSP and Class D amplifiers.
"This means that wherever they are sat in the festival field, each person will receive the same sound image at the same volume," notes the FACE director.
"If a concert organiser wanted to achieve 100dB at the back of the site by the conventional method, he would need to have 110dB in front - by the speaker system. But we wanted to prove that this is now no longer the case. With MLA, the volume can be at exactly the same level throughout the coverage area, while we can limit the sound immediately beyond that - for the neighbours or the festival camp-site.
"The system also ensures that there is virtually no sound return to the stage - so it is nicer for the musicians to play through the MLA."
Karel De Piere recalls that at the Groenplaats, when the local environmental police arrived onsite, they patently disbelieved that the 102dB registering at the mix position would not spill out to the neighbouring businesses and residents surrounding the square. "But what we saw was an alarming tapering off of 12dB [beyond the sound field] over the final 15m - to hit 90dB. People were telling me it was not possible."
The recent evaluation at the FACE HQ in Boom saw Martyn 'Ferrit' Rowe, Martin Audio's technical training manager, demonstrate the theory to around 90 festival organisers, sound technicians and members of the press in a seminar presentation - backed up by practical examples from the Zac Brown Band's American tour.
Next, the assembly repaired to an adjacent park - which also happens to be the location for the dance festival, Tomorrowland - where the site measures 80m wide by 160m deep. Here two PA wings were set at a distance of 24m (with 12-box hangs per side trimmed at a 10mheight). A further 12 MLX subs were stacked adjacent to each other - forming a single broadside array - along the front.
To give the 'festival site' further authenticity, a 'mix tent' (which also contained drinks and heating) was sited at 70m distance from the MLA. Source material was provided by carefully-chosen CD tracks, to demonstrate a wide range of music programme material.
Assisted by Peter van der Geer from Event Acoustics Projects, onscreen readings were taken at 20m, 60m, 80m and the final one at 130m - with one overview screen placed at the mixing position. "We could clearly see the four levels - at the first three measurement positions the level was the same but the drop off was -15dB a
