Uniquely located in a closed metro tunnel, Vienna’s Flex has been hosing club nights and live concerts by newcomers and international acts of various styles since 1990. Flex is not only one of the best known clubs in Europe, but also claims to have the finest sound in the Austrian capital.
The sound system has evolved with installations being planned and installed by Pro Performance, Alcons distributor in Austria, since 2007.
Originally, six Alcons QR36 modular pro-ribbon line source array column loudspeakers were installed on the main floor and two additional QR36s in the café, which is located in a porch adjacent to the club entrance. Three Sentinel 10 Amplified Loudspeaker Controllers were available at this time to drive the systems. In addition, the main floor horn subwoofer system received an update at this time, with five bass speakers being added. In 2007, the requirements were obvious – minimum space requirements and maximum power.
Due for its next evolutionary step, which involved a comprehensive update of all sound systems, the venue relocated its eight QR36 loudspeakers (of which not a single one had failed in 15 years of operation) to the large outdoor area – a true Viennese summer hotspot – where they are being powered and controlled by an Alcons ALC amplified controller.
Since 2022, sound reinforcement duties on the main floor have been shared by eight Alcons QR24 full-range modular pro-ribbon line source loudspeakers (four QR 24/80 and four QR 24/110) with two Alcons QM24 modular line source LMF array extensions. These modular elements form two left and right arrays each 3.3m/10.8ft tall.
Four BC543 cardioid bass systems are placed on the stage, two stacked on each side, with wideband FRPA absorbers from another manufacturer. The specially constructed horn subwoofer system is a concrete bass system with four 15-inch chassis on either side. The BC543s are cardioid subs keeping the bass off the stage (rearward) and work together with the horn (forward) to produce the bass that Flex is known for.
‘The customer needed an extremely flexible solution, as Flex hosts both live events and concerts as well as club nights,’ says Wolfgang Sauter from Pro Performance. ‘The main floor has a great geometry and offers a magnificent sound in combination with the horn subwoofer system. The great length of the room is perfect for Alcons QR24 system. As in any club, at Flex it’s about consuming as little space as possible with any kind of installation
On the main floor, the QR24 and QM24 update offers significantly more headroom as well as better processing. The line source speakers also blend well into the design of the room and perfectly with the horn subwoofer system, which has also been upgraded with new high-performance speakers.
In the Flex Café, however, completely different requirements had to be met. The room previously had sound emission problems prompting the Pro Performance team to choose an end-fire configuration for the bass speakers to optimise bass cancellation at the rear. At the same time, bass traps were installed (at 20, 25 and 35Hz) to guarantee the desired volume in the café. This in turn required additional power in the form of an Alcons LR18 double 8-inch pro-ribbon line array system. In addition to the bass systems, the café’s sound system now comprises Alcons LR18/90 left and right from the stage, two ALC4 sand a Sentinel 10 Amplified Loudspeaker Controller.
‘The Flex Cafe has a low ceiling. We chose the LR18s here because they provide exceptional sound that is evenly distributed across the horizontal plane,’ Sauter says. ‘They combine very well with the bass systems to provide a clear, punchy sound. In total, seven bass traps are used in the café, which significantly improves bass absorption and allows the music to be cranked up even more.
‘Alcons is the sound of Vienna, at least at nightclub level,’ he adds. ‘Flex was the first club in the world to use Alcons loudspeakers. The reliability and overall manufacturing quality were a major reason for the customer to choose Alcons. In recent years, we at Pro Performance have installed Alcons Audio solutions in a whole range of venues in both Vienna and across Europe, with the installation at Flex being something very special. Back in 2007, a loudspeaker shootout was held at the club, which Alcons won not only because of the excellent sound quality, but also because there were no other vertical column loudspeakers available on the market at the time. And in 2022, Alcons is still ahead with its QR24 series.
‘Flex is very satisfied. The café had always been the venue with acoustical sound issues. Now it has transformed into a floor that can easily compete with the finest Vienna has to offer. Together with the incredible main floor, Flex is undoubtedly reporting back to the top of the European club scene.’
