SSE Audio Group has taken delivery of the first production NEXO GEO T Tangent Array Systems, a total of 96 full-range Tangent Array cabinets and twenty-four CD-18 Controlled Directivity sub-bass units.

The order is a reflection of SSE's close involvement with the NEXO GEO Technology project, from the conceptualisation of the first tangent array devices, the GEO S Series launched in 2001, to the realisation of the GEO T Series and, in particular, its remarkable flying system, designed by Chris Beale, SSE's Group Hire Director.

SSE has been field testing GEO T full-range and sub-bass units since the summer of 2002, with the complete system fulfilling its potential most recently at the larger venues on Tori Amos' European tour. At Le Zenith in Paris, before a 7,000-strong crowd, the SSE/Melpomen team flew single arrays of seventeen T4805s on each side of the stage, with four CD18 sub-bass units. The system was entirely powered by Camco Vortex 6 digital amplifiers, with NEXO 241 digital processing.

SSE Audio Group has already deployed a 36-element GEO T system to Melpomen in France, to enable field evaluation to continue in an atmosphere of good food and fine wine. In the UK, the first large-scale outing for the system will be for the rescheduled Oasis dates in early March.

"The loudspeaker that has been planned and developed for so long has finally become a reality," says Chris Beale of SSE. "In use, GEO T opens up new ways to address complex acoustic problems. Reverberant rooms can be tamed, environmental issues solved and new microphone techniques explored with results that were hitherto unobtainable.

"In R&D terms, NEXO has really pushed the boat out, and they've been brave both in the use of materials and the overall design. The result cannot be compared directly with other line array loudspeaker systems because it is not a line array in many physical respects. It is rather a truly tangent array-able composite device, designed and built with extreme precision to propagate the most accurate sound field you will have ever experienced. Of all the systems I've worked with, this is by far the most capable."

In 2001, the question on everybody's lips was "does the world really need another large line array loudspeaker?" For a company like NEXO, whose purpose as an organization is defined by its technical contributions to the science, art and business of sound reinforcement, there seemed little point in joining the crowd of manufacturers offering heavy and cumbersome cabinets, all with similar attributes and shortcomings.

nstead, Eric Vincenot and his team focussed their development on a tiny yet immensely capable tangent array loudspeaker system, the GEO S Series. With this product, they were able to evaluate new patent-pending technologies such as the Hyperbolöid Wave Guide, Directivity Phase Device and Configurable Diffraction Slot, along with DSP-driven cardioid sub-bass loudspeakers. The GEO S has already proven itself a superior alternative to the small line array devices that it most closely resembles. The R&D team realized they had a powerful new technology platform; the question was where to take that platform next.

Eric Vincenot, NEXO's Technical Director, explains that "the larger-scale T Series was in mind from the outset, but its specification grew from the success of GEO S, which demonstrated that incredible results were achievable, providing that the physical rules were strictly obeyed. The software modelling showed that the penalties for even small compromises in design would be enormous; however, the no-compromise solution demanded extreme accuracy in construction of the cabinet and particularly the rigging system."

For the GEO T4805 Tangent Array Module, new materials and advanced loudspeaker devices were sourced and the R&D team was expanded to apply expertise in the GEO-critical areas of cardioid technology, software, signal management programming and rigging system development.

Each T4805 loudspeaker element is constructed of part birch ply, aluminum and moulded composites and weighs only 50Kg (inclusive of its flying hardware). It has fully controlled directivity from 60Hz to 16kHz by virtue of its advanced acoustic profile, cardioid mid-bass loudspeaker configuration and its extended hyperbolöid wave-guide. "Each element is a fraction of the size and weight of the products with which it easily competes," says Vincenot, "and we're absolutely confident that GEO T has optimum proportions, even if it is a quarter of the size of other high output vertical array modules."

In order to achieve low weight with high performance, new developments in very high power cone loudspeakers were needed. The large, heavy and poorly coupled 15" and 18" loudspeakers in conventional line arrays were replaced with small, efficient cardioid devices that were able to produce equivalent mid-bass output and vertical pattern control with more consistent horizontal directivity. Because the largest transducer in GEO T Series Tangent Array Modules is an 8-inch cone, the height of each element can be minimized. This is critical in order to provide the best possible high-frequency resolution.

Such a device puts unprecedented demands on the flying hardware, and SSE's Chris Beale has devoted hundreds of man-hours into developing an extremely accurate rigging system that is exceptionally easy to install and remove. "It's a precision instrument," he explains. "The error from top element to bottom in a ten-element array is better than 0.1 degrees and the system can be easily rigged in its own footprint by one crewperson.

"With the emergence of GEO technology, the accuracy of the rigging system has become a critical part of the product design," says Beale. "However, the factors of safety and the commercial demands for speed in rigging and de-rigging have never been greater. The concept for GEO T hardware was to implement a system that did not require that the cabinets be pre-connected in a ‘train’ on the floor, as this is extremely space consuming and awkward on uneven surfaces. The elements had to interconnect easily and quickly and the J shape of the array had to be created in the air rather than on the ground."

Safety is always a primary concern when designing an array hardware system. Extensive software modelling, confirmed by physical pull tests, was used to identify the changes in loading parameters when the array is configured to the audience area. "The system had to be able to support very long lines of up to 36 elements and had to be capable of providing large upward and downward angles without overload. It also had to be able to ground-stack without accessories and without excessive effort. All of these goals have been achieved and we believe GEO T has the most comprehensive, safe and ergonomic rigging system currently available."

SSE's GEO T cabinets are safely protected in a custom-designed flight case system. Each case contains three GEO T elements or can carry two elements plus one bumper assembly. This degree of protection is desirable both to ensure that the accuracy of the rigging system is not compromised by impact damage and generally to maintain the condition and therefore the value of the product. The GEO T is to audio what a moving light instrument is to lighting – a precise tool that deserves rugged and roadworthy packaging.