ALA Series

Acoustic Linear Array Loudspeaker System

A properly designed linear array can have enormous benefits in many applications, especially in problematic venues. The Apogee Linear Array Series is an intelligent and practical implementation of both the doublet principal and the line array principal characterized by Olson and published in 1957.

Each model in the series behaves similarly, but each is scaled in size to perform optimally in a specific range of applications.

 

Why A Linear Array?

An Apogee Linear Array behaves quite differently from a conventional loudspeaker.

Each Linear Array enclosure is really a modular component of a complete system. Modules are designed to be used in multiples; thus, a system might consist of three or four modules as a minimal configuration, and as many as ten, twelve, or more, in order to obtain the desired power and coverage needed for larger venues.

The primary benefits of the linear array are the extremely narrow vertical coverage angle of each module and the seamless acoustic transition between multiple units. By starting with a narrow vertical angle, an array can be constructed that produces the exact coverage required and nothing more. Modules may be assembled in 'flat-pack' formations, 'tight-pack' formations, or combinations of both (as shown in the photo, opposite right). When tight-packed, each additional module adds 10 degrees of vertical coverage. Flat-packing the modules adds 5 degrees, plus 6 dB of additional forward radiated power. In either case it's easy to calculate the obtainable power levels and the resultant dispersion pattern.

The predictability of the system gives the designer the means to accurately direct the acoustical energy to the audience areas, but not beyond. This precise pattern control eliminates unwanted spillage onto ceilings, floors, walls and other surfaces, which would otherwise cause destructive reflections.

How Apogee Linear Arrays Achieve Control

The pattern in the mid and high frequencies is obtained by a coupling of paired waveguides in each enclosure. This coupling sums the forwarded radiated power while narrowing the vertical dispersion. Low frequency vertical pattern control is governed by the total size of the array, and as modules are added, the pattern control extends to lower and lower frequencies. As an example, an array of ten ALA-5s will provide controlled dispersion down to 60 Hz.

Horizontal dispersion in the high frequency range is controlled by the HF horn flares (horns are available in either 60 degree or 90 degree formats). Horizontal dispersion in the low frequencies is achieved by a refinement of the doublet principal. The precise spacing and angulation of the paired cone drivers produces a well-defined directional pattern that maximizes forwarded-radiated power while attaining superb off-axis rejection. Crossover points are carefully chosen to avoid destructive cancellation in the upper frequencies from the spacing of the cone drivers.

Line it up!

It All Lines Up

ALA speakers bring a new experience to sound reinforcement. Vertical pattern control is like nothing you've ever experienced; horizontal patterns can be ordered in either 60 or 90 degree formats for optimum design flexibility, and off-axis rejection is nothing short of astounding. The result is greater clarity, articulation and coherence, with phenomenal freedom from feedback. In many cases an ALA system can eliminate or reduce the need for delay speakers, and/or critical placement of mics to achieve adequate gain levels. Apogee's ALA Series will transform your most troublesome shows and installations into 'another job well done'.

Rigging and Handling

Apogee Linear Array Speakers use a simple and effective rigging system (patent applied for). The enclosures are joined together with various lengths of connecting bars to achieve the desired angular relationship (see photo right). The bars are secured in place by aircraft grade retention pins. Configurations can be altered in seconds, without any special skills or equipment. The rigging system is equally effective for stacking enclosures on ground supports when augmented with optional outrigger bars.