> Technologies > Beam Forming

Beam Steering: Innovative Evolution = True Output Control

In 1997, EAW proved with the large-format KF900 Series that high-resolution measurements of each individual driver in an array could serve as the basis for an advanced modeling program that accurately predicts total array performance at a variety of locations. Further, by manipulating various DSP parameters, this modeling program could optimize performance and even steer the array’s overall output.

At that time, a loudspeaker technology capable of producing a coherent impulse both intelligible and musical at distances up to and beyond 700 feet was a sort of “Holy Grail” for high-end professional loudspeaker manufacturers. Despite the considerable difficulty of the task, EAW engineers set out to do just that. Rather than simply creating a specialized tool to achieve extreme long-throw with existing arrays, our approach instead solves the true problem: incoherent sound wave summation from multiple drivers.

To solve the problem we first optimized all well-documented electro-acoustic elements that would apply to the loudspeaker array. Transducers would need to be very efficient and capable of very high output and waveguides would need large mouths and long throats to achieve the highly controlled pattern required.

Called Phased Point Source Technology (PPST)) as developed for the KF900, this approach leveraged the ever-increasing power of digital processing to create a unified source sound impulse at all points within the coverage area. KF900 loudspeaker modules used newly engineered mid- and high-frequency drivers packed into the smallest possible space and loaded on then-new SimplePhase™ horns.

Building on EAW’s previous use of phase and frequency “shading” techniques to manipulate beam profiles and to blend vertically dissimilar subsystems, this technology integrates KF900 loudspeaker modules into a single acoustical element the beam profile of which can be adjusted and even steered in the vertical plane.

Following the extraordinary success of the KF900 Series that continues to this day, preliminary work began on a highly compact, single-enclosure array capable of this same control. Over the next few years, experimental prototypes proved the concept to be a valid one, and work began in earnest on what would become the DSA Series.

Like all EAW loudspeakers, DSA loudspeakers would need to deliver high-output, high-definition performance within the constraints of its given application. The given application, in this case, was defined as the small to mid-sized installation in spaces with problematic acoustics.

Peak output should be in the neighborhood of 120 dB SPL to provide adequate coverage. Since speech intelligibility is a critical issue for these facilities, the system should provide maximum clarity through the vocal range. Broadband frequency response would also be needed to deliver full range music reproduction. Finally, the system would need to deliver outstanding fidelity, an enduring EAW engineering goal.

Almost from the beginning, EAW engineers decided to model the DSA enclosures on the traditional column loudspeaker. In addition to minimizing visual impact, this configuration would enable the creation of a line array that was central to steering output in the vertical plane.

To this point, balancing enclosure size against driver placement represented the first substantial obstacle in DSA Series development. While longer lines extend line array benefits to lower frequencies, the applications demanded minimal enclosure size. Therefore, engineers decided to create two different enclosures – a primary full range system (DSA250i) and a secondary LF-only system that would extend pattern control when needed (DSA230i).

The design engineering phase of the DSA project began with the assumption that a single DSA250 loudspeaker would meet the minimum performance requirements. To achieve the necessary broadband pattern control, the LF section’s line length was specified to provide meaningful pattern control to around 300 Hz. EAW engineers created a line comprising eight 4-inch LF cones, slightly offset to help minimize enclosure height. This closer vertical spacing creates a higher resolution that optimizes DSP control.

Output and driver spacing drove the HF section design, where EAW engineers loaded eight 1-inch soft dome tweeters with a single, very shallow, multi-cell horn. The goal was to keep the drivers’ acoustic centers as close as possible. Again, this high-resolution design optimized DSP control to substantially higher frequency than previously achieved. Indeed, actual performance exceeded the engineer’s expectations with steerability to 16 kHz.

Each DSA250 loudspeaker delivers a fixed 120° horizontal coverage pattern. This wide-angled coverage allows for fairly wide horizontal spacing between DSA250 modules in an installation with the systems vertical steerability virtually eliminating the dead spots in between.

To simplify installation, set up, and long term use, engineers designed all signal processing and amplification as internal components of the loudspeaker system. Each DSA250 loudspeaker delivers 480 Watts of power – eight 40-watt LF,  eight 20-watt HF, as well as 16 channels of complex DSP that includes conventional HPF and LPF, delay, PEQ and limiting as well as proprietary filters developed specifically to facilitate steering. The internal power and DSP modules also incorporate a robust driver and electronic protection system.

When connected, all DSA Series loudspeakers in an installation comprise a network in which the companion DSAPilot control software recognizes each individual loudspeaker as well as arrays of loudspeakers acting as a single unit.

DSAPilot was created on a separate development path from the DSA Series loudspeakers, with its roots stemming from the KF900 project's optimization program, FChart. FChart uses high-resolution measurements of each individual driver in an array to predict and optimize total array performance. DSAPilot employs this same approach to control multiple loudspeakers in a total installation environment.

DSAPilot assists in both the design and the installation of a complex sound reinforcement system, yet it requires no advanced acoustical knowledge. Once it is provided with the dimensions of the room and the location of the DSA Series loudspeakers, DSAPilot controls the DSP settings to form a vertical beam matched to the space. While the control computer can be disconnected after installation, many users will prefer to leave it connected for monitoring purposes and rely on DSAPilot’s multi-level password protection to prevent tampering.

Ultimately, DSAPilot allows users to create multiple DSP configurations to meet a variety of needs such as multiple zones or voice-only/music options. DSA Pilot is a user-friendly software program that assists designers and installers through the process of overall sound system design and installation.

DSAPilot does not attempt to replace the designer. Indeed, it is helpful to develop a detailed sketch showing loudspeaker placement and horizontal coverage before working with the software.