Specifications

The listener hears the vector sum of more and more cabinets as he moves further

away from a straight line array. These increasing contributions partially compensate

for the normal reduction in sound pressure with distance from source.

Note that farfield spl levels will increase towards the centre of the array where more

elements add.

W8L Series

The classic explanation of line array behavior assumes omni-directional point source

drive elements that must be positioned within ¼ wavelength at their highest operating

frequency for coherent summation. Martin Audio designs comprise directional horn-

loaded sections. This closely coupled horn technique modifies the equations allowing

greater driver spacing. See our Institute of Acoustics, Reproduced Sound 2003 paper,

Advances in Line Array Technology for Live Sound.

Note that our mid and hf designs do not try to emulate a dead straight ribbon.

Practical loudspeaker columns must have vertical coverage patterns tailored to suit

the audience size and shape and our line array systems have been designed with this

in mind. The W8L Series are deliberately designed to produce slightly curved vertical

wavefronts - enough to allow up to 7.5º of vertical splay to be introduced between

boxes but not enough to affect straight line performance.

Progressive Curvature arrays

Straight columns (0º splay angles) produce far-field high-mid frequency sound

pressure levels that increase approximately 6dB for every doubling of W8L quantities

but, as inter-box splay angles increase, the vector sum of multiple W8Ls decreases

through 3dB for a 3º splay to 0dB (no summation) at 7.5º. This Progressive

Curvature provides smooth level coverage without amplifier channel trimming for

most applications.

Martin Audio’s ViewPoint

software calculates the optimum progressive curvature

for a given audience area. The progressive curvature produces a more consistent

frequency response from the front rows to the rear seats than often used J-shaped

arrays having a straight, long throw section at the top and a curved lower section. An

over-angular J-shaped array acts like a foreshortened straight array above a point

source array and creates vertical lobes that result in irregular coverage.

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