Table of Contents
Advertisement
Unfortunately, the line array effect can also be limited by other factors:
Real-world arrays tend to be acoustically small at low frequencies – restricting
the low attenuation region to just a few metres
Air absorption can cause excess attenuation of high frequencies and can be a
significant factor over medium to long distances as it has a linear dB
characteristic with distance (i.e. it may be quantified in dB/m)
Coupling between adjacent elements can be imperfect at high frequencies
because cabinet to cabinet spacing is significant at very short wavelengths. This
is minimised for W8L Series systems by placing the cabinet-to-cabinet hinge at
the front.
W8L Series
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
º
allow up to 7.5
of vertical splay to be introduced between boxes but not enough to affect
straight line performance.
Curved arrays – determining inter-cabinet splay angles
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 7.5
level coverage without amplifier channel trimming for most applications.
ViewPoint™ and DISPLAY™ software
Martin Audio's ViewPoint and DISPLAY 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 the commonly used J-shaped
arrays that have 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.
ViewPoint calculates the maximum summation point (near the top of a progressively
curved array) and aims this towards the furthest listening area. A progressive curvature
array's HF coverage weakens dramatically above the maximum summation point so this
point is regarded as the Coverage Stop.
ViewPoint simply advises on the appropriate array geometry and controller presets for a
given 2-D room geometry. DISPLAY™ operates may be used in 2-D or 3-D and predicts
polar responses, coverage levels and frequency responses.
º
. This Progressive Curvature provides smooth
All material © 2007. Martin Audio Ltd. Subject to change without notice.
Hide quick links:
Advertisement
Table of Contents
