L-Acoustics V-DOSC, Operator'S Manual

Page: 14 / 158

L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 14 of 158
V-DOSC: THE SOLUTION
V-DOSC is the first loudspeaker system designed based on the principles of WST and can be
considered as the first modern generation line source array. It should be stressed that there is a big
difference between a line source array (such as V-DOSC, dV-DOSC, KUDO or ARCS) and other line
arrays on the market today. Whether a line array correctly behaves as a line source array depends on
the extent to which the 5 WST conditions outlined in ''Wavefront Sculpture Technology'', JAES Vol. 51,
No. 10, October 2003 are satisfied.
This may seem like semantics, but there are scientific and
technical reasons why V-DOSC works (not marketing reasons!).
V-DOSC was designed as a system consisting of identical, vertically-arrayed loudspeakers that satisfy
WST conditions for angles of 0° to 5.5° between adjacent enclosures. Individual components are
physically arranged within each enclosure so as to meet WST conditions, frequency band-by-
frequency band, when the enclosures are arrayed together. Each enclosure radiates a flat, isophase
(constant phase) wavefront, allowing the overall assembly to coherently couple as a single extended
line source. Since the angle of separation between adjacent enclosures is adjustable, the radiated
wavefront can be focussed by physically shaping the array. By satisfying WST criteria over the entire
audio bandwidth, the engineer or designer is provided with a "single" loudspeaker with well-defined
coverage and wavefront shape, thus allowing the geometrical distribution of energy to be precisely
installed to match the geometry of the audience seating area.
The internationally-patented
1
DOSC waveguide is the core technology in V-DOSC that allows the first
and third WST conditions to be satisfied for frequencies higher than 1.3 kHz, i.e., the wavefronts
generated by individual DOSC waveguides are planar and their combined surface area accounts for at
least 80% of the target radiating surface area provided the angle between adjacent enclosures is less
than 5.5 degrees.
For traditional horn-loaded systems, coherent summation is not possible at higher frequencies since
the wavelengths become progressively smaller than the physical separation between the acoustic
centres of horn and driver assemblies. Neither of the first two WST criteria can be satisfied and, as a
result, interference occurs throughout most of the high frequency range (see Appendix 1).
By comparison, a V-DOSC array is a full-spectrum, coherent loudspeaker system - even for the
highest frequencies. As with any speaker system, interference occurs, however for V-DOSC the main
difference is that within the defined coverage region the interference is constructive while outside it is
destructive (see Appendix 2). For more details on how V-DOSC satisfies WST criteria, please refer to
Appendix 3. For further information on the DOSC waveguide, please see Appendix 4.
V-DOSC enclosures are vertically arrayed in two or four characteristic "J"-shaped columns. Since
enclosures of the array couple coherently, the enclosures are physically smaller and fewer cabinets are
required in comparison with conventional systems. This makes V-DOSC very cost-effective for
touring sound applications where transport space and handling time means money. These properties
also make V-DOSC highly effective for fixed installation where compact size combined with
predictable coverage is important.
One of the key benefits of WST is the predictability of the radiated wavefront's shape. Horizontally,
the entire V-DOSC array has the same coverage as a single enclosure (90°). Vertically, the coverage is
equal to the sum of the angles used between individual enclosures of the array. Given this
predictability, vertical coverage can be quickly optimized to match the audience geometry using either
L-ACOUSTICS ARRAY or SOUNDVISION software. These convenient, user-friendly software
programs help the operator determine how to focus the wavefront so that tonal balance and sound
pressure levels are evenly distributed throughout the audience (WST rule #4). Using either of these
programs, array design can be conveniently performed and installation parameters determined on a
case-by-case basis to optimize coverage for each venue according to the audience geometry.
1
The DOSC waveguide is registered under European patent n°0331566 and North American patent n°5163167. Please see
Appendix 4 for a description of the DOSC waveguide.