Wall of Bass

To be late or just miss things is simply very annoying. And usually we are not used to this, but this time it is 145 years we are late. Really annoying! Thereby it could have been so exciting if both involved parties had met each other in reality.

Graz 19. November 1868

Highly honored Professor Kundt,

I hasten to come back to your friendly letter and honorable request which it contains, and hope you won’t consider this answer as given heedless just because it is given fast. To the contrary I already strived after acceding your overture, the progression of your discovery, the first walk able Kundt’s tube to visit, and experience same with body and mind. You already know the address in Wiener Neustadt. I’m glad to consider this encounter as a great luck for the prosperity of this science.

Most respectfully,
Lambda Labs

As for today, without using time machines this undertaking stays an intellectual game, and maybe professor Kundt would have had no joy by visiting this location if he came to know that the rear of this walk able tube, the “Wall of Bass” installation in the club SUB in Wiener Neustadt, has no acoustically hard delimitation but an integrated bass trap destroying his just discovered standing waves. But let us stop turning back the clock 145 years, let’s turn it just to the beginning of the “Wall of Bass”.

The requirements were clear. The name of the completely reconstructed “SUB” had to be put into action and integrate an exceedingly perfect low frequency solution which should be capable to reproduce bass music, live concerts, DJ-lines, readings, minor arts and cabaret as well as workshops and theatrical performance in a spectacular and revolutionary way. In addition, the SUB is located at a housing area and directly borders on neighbors, which made the protection of local residents become a main focus of attention, but finally the planning of an acoustical high-tech sound installation could settle the matter. A word and a blow.

On the backplane of the 6 x 5 meter large stage, which adjoins to the 100 square meter comprising tube like main floor, firstly, each 400 kg heavy special concrete blocks were cast and then set up to a 6 x 3 meter large and 13 tons heavy concrete wall reaching all room delimitation, which required an own 35 tons heavy concrete foundation. A huge effort, which was accomplished in particular through the utmost commitment of all SUB club members.

Each concrete block serves as loudspeaker enclosure with pressure-resistant rear chamber which as a matter of principle decisively implements the perfect Impulse response of a “closed-box” design and maximizes the radiation resistance of the woofers through the acoustically hard surface. A self-enveloped 15" speaker was produced for the “Wall of Bass” and adapted to the unusual demands of this project. The single chassis are arranged in a way that makes them act together like one single swinging wall. The principle of function is similar to a piston in a cylinder. A perfect plane wave is created in the interior of the club, which moves along the side walls and naturally don’t induce any room modes. The back side of the main floor was converted into a single bass trap which finally absorbs the incoming wave. Herewith the SUB receives an acoustical result that could never be reached even outdoor.

Oh, by the way outdoors? Outside there can’t be heard practically nothing. More likely the urban traffic turns out to be the nightly molester, not the club sound system. The bass frequencies goes by the walls, not into it.

Reinhard Nell and Wolfgang Sauter, the project managers of the “Wall of Bass” themselves are impressed: “Due to the experience and the possibilities of modern simulation you surely expect a certain result, but such an operating range and evenness of the low frequencies is overwhelming. And the data we measured melts in one’s mouth,” said Reinhard Nell: “This sound installation here plays down to 7Hz flat! This means, that the group delay of this installation, even in the infra bass range, is that small, whence results an impulse response where, and I dare to say that, is unique. The sound pressure level at even this frequency is wide beyond 140dB and this at ANY point in the room absolutely equal. Not that anyone would need such sound pressure levels, but just imagining heaving so much headroom is unbelievable. You don’t have the possibility to feel 7Hz on your whole body every day, and I can tell you, this is an experience one should make. Unfortunately we didn’t find any music titles which could deliver such frequencies. Few movies sometimes play down to 20Hz, what makes the wall of bass also interesting for cinema installations and open up fully new possibilities. Or maybe this possibility encourages some artist to produce even lower bass lines” Reinhard Nell cheers. “The possibility to reproduce it is now made.”

The integrated OEM 15" long excursion drivers of the “Wall of Bass” with ±25mm linear excursion, are driven by each 800 Watt amplifying modules, what makes the overall power of 25 kW look much at a first glance. The maximum desired sound pressure level however is reached already at an excursion of only ±3mm. Therefore the “Wall of Bass” gets by with only 500 Watt peak music power during operation, which even sets new standards of energy efficiency.

As high-end DJ-monitoring and as a flexible and extremely audiophile monitor on stage, for the first time, the new coaxial 15" signal mirror CX-3A is brought into action. In the high frequencies this extreme power monitor uses a beryllium membrane which is naturally free from partial oscillations, and delivers a worthy acoustical solution to the “Wall of Bass”. Six CX-1A and four CX-1B inconspicuously perform support.

The “Wall of Bass” got about in the meanwhile and we already had to extend the demonstrations before the opening date. The Austrian Theatre Technical Society already plans to hold their next meeting here, and numerous famous artists already announced their visit, although some of their fees normally can’t be paid by clubs which aren’t of large-capacity, the club managers rejoices.

If you might have interest to visit the “Wall of Bass” in Wiener Neustadt, just enroll in our overview of events at the time given. We’ll be glad to consider this encounter as a great luck for the prosperity of this science.