December 16, 2013, by PSW Staff
Powersoft D-Cell504 IS high power amplifier modules have been specified to drive a unique “Wall of Bass” in an Austrian nightclub that provides response to as low as 7 Hz.
The newly-reconstructed Club SUB, in the city of Wiener Neustadt, set out to integrate an optimized low-frequency solution, capable of reproducing a wide range of live and DJ-derived music (Drum ‘n’ Bass, Dubstep and Techno) and arts presentations, as well as workshops and theatrical performances.
And since the 300-capacity SUB is located in a heavily populated residential area heavy emphasis needed to be placed on acoustic isolation to avoid noise pollution. These were the challenges faced by project managers Wolfgang Sauter (from pro performance) and Reinhard Nell (from Lambda Labs).
Speaking of the background to the project, Lambda Labs German based director, Steffen Kroschel says, “The owners’ goal was to achieve a similar sound performance as it had in the Grelle Forelle Club in Vienna. Given the concerns of local residents, when Mr. Sauter surveyed the building, with its tube like architecture, the abstract idea of a ‘vibrating wall’ became more logical.”
He contacted Lambda Labs, where Nell supported the concept with simulation data, parameters and measurements, applying his knowledge of high-performance concrete “closed box” enclosures and amping. The drivers were developed especially for this application, going through 10 prototype stages, while the club owners helped with casting the concrete loudspeaker enclosures.
For the rear wall, behind the 6 x 5 meter (approximately 19.7 x 16.4 feet) stage, 400 kg (about 880 pounds) special concrete blocks were cast and set into a 6 x 3 meter (19.7 x 9.8 feet) wall, using 13 tons of heavy concrete and a further 35 tons for the foundation, requiring a monumental effort (shown in photo at right).
(click to enlarge)
“It was extremely difficult to handle these enclosures with small forklift trucks and build the 50 cm deep low frequency absorber,” Kroschel says.“Behind the wall is sand, and under the wall, Mr. Sauter chose material that is used for highway construction.”
Each concrete block serves as loudspeaker enclosure with pressure-resistant rear chamber which implements the optimized impulse response of a “closed-box” design and maximizes the radiation resistance of the woofers through the acoustically hard surface.
A self-enveloped 15-inch loudspeaker was produced and adapted to the unusual demands of this project. The single chassis are designed to act together like one single swinging wall, in a similar principle to a piston in a cylinder.
Kroschel explains the concept further: “A perfect plane wave is created in the interior of the club, which naturally moves along the side walls and doesn’t induce any room modes. The rear of the main floor was converted into a single bass trap to absorb the incoming wave. The SUB thereby achieves an acoustical result that could never be reached even outdoors.”
And as for outside, there is virtually no noise escape, with both Nell and Sauter agreeing that “such an operating range and evenness of the low frequencies is overwhelming.”
But to achieve this optimum performance, every driver needed be powered by its own dedicated amplifier module to take advantage of shortest cable runs, perfect matching power supplies and impedance data. As a long-term partner of Lambda Labs, Nell chose Powersoft to provide amping for the “Wall of Bass,” while Lambda Labs supported the installation with items like amplifier mounting frames.
“As we have been using Powersoft amplifiers in our regular self-powered loudspeakers for four years, it was obvious to choose the company again for this project as we have a lot of experience with their modules, such as the Digimod 1500, which we use successfully in our subwoofer product MF-15A and our full range enclosure TX-3A,” Kroschel notes.
“Their amplifiers deliver stable power also in the low frequency range, are small and lightweight, and fulfill most of our demands regarding sound quality,” he continues. “For the project, we used the D-Cell, because it is very compact and still delivers plenty of power.”
The 32 Lambda Labs OEM CX 15-inch ultra-long excursion drivers, with ± 25mm linear excursion capability set in housings made from special concrete. Each is driven by 800-watt amplifying modules, with the maximum desired SPL reached at an excursion of only ±3mm. Therefore, the “Wall of Bass” manages with only 500-watt peak music power during operation, providing great energy efficiency.
Via the 2-channel 32 D-Cell504 IS amp modules, Powersoft was able to deliver 25,600 watts of amplifier power. In addition, special mid-high loudspeakers generate a cylinder wave for longer throw and less room reflections while the DJ reference sound is provided by CX-1A and CX-3A self-powered monitors with Powersoft D-Cell modules.
Available in both 2-channel and an incredibly compact 4-channel model with two amp units, D-Cell504 IS will power 2-way loudspeakers with up to 2 x 350 watts into 4 ohms or 1 x 700 watts in bridge mode at 8 ohms – or even 3-way systems with up to 700 watts on the low end.
Performance is enhanced via PFC power supply, allowing error proof operation, and Class D output stage, also available with DSP on board.
Integrated within an elegant aluminum heatsink panel, the D-Cell504 IS provides an interface panel with input volume potentiometer, double XLR for mono input and link out or stereo input operation, four LED for Limit, Clip, Signal and Ready signalling, with a 4-LED preset selection button to show the preset in use.
Easy access to the DSP mounted on board, is further facilitated via remote control capabilities provided by Powersoft’s proprietary Armonía Pro Audio Suite.
“The data we measured melts in one’s mouth,” says Nell. “The sound pressure level is beyond 140 dB and absolutely equal at any point in the room (not that anyone would need such sound pressure levels). And you don’t have the possibility to feel 7 Hz throughout your whole body.”
Summing up, Kroschel says that everyone who has played through the system has been impressed.
“For some it has changed their awareness of music,” he concludes. “Although we have not been able to find movie soundtracks with lower frequency response than 20 Hz, during our live presentations of the ‘Wall of Bass’, we play an original recording of a Challenger rocket launch, to give a natural idea of the breathtaking force. Another show element was to generate some sine waves down to 7 Hz, demonstrating this outstanding response by also making the acoustic waves visible with smoke.”