The town of Boom in Belgium is the unlikely host to Tomorrowland, and the 400,000 dance fans that attended the three-day évent this year.

Marking its tenth anniversary, headliners included David Guetta, Steve Aoki, Armin van Buuren and Aviici. Its reach is also extend around the globe, with corresponding évents appearing in Brazil and the US.

NoizBoyz and Phlippo Productions have handled the sound for the past four years, serving multiple stages that are not only in close proximity, but also run simultaneous acts.

Minimal sound spill from stage to stage is a key factor to festival-goers’ enjoyment, but the local authorities also impose restrictions on noise levels. NoizBoyz chose multiple L-Acoustics K Systems to successfully tread the line between all considérations.

‘While the main and secondary stages were at opposite points of the grounds, the problem lies in those areas in the middle where you need the best sound possible, but you are dealing with significant bleed and that makes it pretty tricky,’ the sound team explains. ‘In these cases, isolation is critical and where we know we can rely on the K2 and the cardio sub to really come into play. The K2 has exceptional directivity control, both horizontally and vertically. In fact, the control is so good, you can almost stop the beams where you want them to, so we didn’t have any audio going out to places where we didn’t want it.’

Since Belgian law enforces strict sound limits on outdoor events, measurements were taken by independent consultant DB Control in areas surrounding the festival and at FOH for every stage. NoizBoyz relied on L-Acoustics Soundvision to model the festival grounds in 3D and simulate the perfect acoustical solution with real-time mapping on both coverage and delay.

‘The difference between our predictions and our real-time measurements was absolutely zero,’ Noizboyz reports. ‘Our main stage faces a steep hill, and Tomorrowland is known for its elaborate décor. Not many system design programs can generate a correct shoot for those kinds of obstacles that are so crucial to good sound design, the fact that Soundvision handles that kind of mapping ensures that we have a clear throw for the arrays.’

From the main stage, which lies at the bottom of a valley, the festival producers wanted to avoid ruining sight lines with delay towers. NoizBoyz achieved 160m throw using two hangs of 14 K1 reinforced by four K1-SB. Two further hangs of 16 K1 boxes with four K1-SB subs provided side fill, Kara catered for both the fills, whilst low-end reinforcement was via 40 SB28 subs.

The Opera stage was equipped with two hangs of 12 K1 boxes accompanied by four stacks of Kara for fills, plus 30 SB28 subs.

Because each of the eight stages features a different style of music, NoizBoyz aimed for a neutral sound. Harder dance music was to be found on the Frames stage: ‘For this area, a sub with great performance is essential, and the combination of K1, K1-SB and SB28 delivers impeccably,’ Noizboyz reports. For Candy Arena, which is a techno area, we used K2, as we feel that its low end is really tight. K2 gives us exceptional horizontal control which allows us to minimise reflections from the sides of the tents, so we used them in all of the indoor areas.’

The Candy Arena used 18 K2 boxes, four Kara and 20 SB28 subs.

Built on a floating platform, The Garden of Madness required weight to be kept to a minimum : ‘K2 is not only light but it's easy to control the horizontal directivity; and the fact that it offers a maximum inter-box angle of 10° made it possible to cover a bigger area with a smaller array,’ Noizboyz says. Here the system consisted of 20 K2 boxes with six Kara and 20 SB28 subs.

‘The quality of sound coupled with the great ergonomics and flexibility of the L-Acoustics K system makes it very easy to work with,’ says Phlippo Productions Product Manager Jonas Gyssens. ‘The K2 with its 10° hook and the K1-SB’s extended low-end give us a lot of options. The K2 combines an open and clear sound with a ton of power and the fact that it's so lightweight and easy to rig, means it's the ultimate multifunctional cabinet. And the more multifunctional a loudspeaker is, the more it fits the needs of our productions.’