L-Acoustics dV-DOSC, Operator'S Manual

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dV-DOSC dV-SUB Manual V3.0 June 2005
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First V-DOSC, Now dV-DOSC
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. Note: the “V” in V-DOSC refers to the V-
shaped acoustic lens configuration employed for the mid and high frequency sections. It should be
stressed that there is a big difference between a WST-based 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 dV-DOSC works (not marketing
reasons!)
As stated above, dV-DOSC can be considered a derivative of V-DOSC since it performs according to
the same principles except in a smaller format. An important design objective for dV-DOSC was to
provide expanded horizontal and vertical coverage and this was achieved in two ways - first, the V-
shaped acoustic lens section for the low section (that also acts as a waveguide for the high section) was
engineered to provide 120 degree horizontal coverage in comparison with the 90 degree coverage of
V-DOSC. Secondly, the innovative construction of dV-DOSC employs minimum thickness top and
bottom aluminum plates and the rigging system pivots around the front points of the enclosures -
these two features bring the openings of the individual DOSC waveguides (one per enclosure) as close
together as possible, allowing dV-DOSC to be used up to a maximum of 7.5 degrees between each
enclosure while still satisfying the greater than 80% fill WST criterion. By comparison, V-DOSC
enclosures can be arrayed up to a maximum of 5 degrees between enclosures.
dV-DOSC enclosure trapezoidal angles have been engineered so that 7.5 degrees per enclosure is
obtained for tightly wrapped arrays. Starting from a tightly wrapped array (7.5 degrees between
cabinets) the backs of the dV-DOSC enclosures can be progressively opened up using dV-ANGLEP1
or dV-ANGLEP2 rear angle bars by selecting various hole positions to produce variable curvature
arrays. A flat array is obtained using the maximum extension hole position on dV-ANGLEP1 for all
enclosures. Array curvature obtained using dV-ANGLEP is described as convex and the array shape
corresponds to the positive curvature that we are familiar with.
If dV-ANGLEN rear angle bars are selected, concave or negative curvature arrays can be constructed
(to visualize a negative curvature array, think of a satellite dish). A flat array is obtained using the
minimum hole position on dV-ANGLEN and the array becomes progressively concave as hole
positions with greater spacing are selected. Experimentation in the use of negative curvature arrays is
ongoing and it is thought that such arrays will be useful for longthrow applications and for acoustic
holography effects where it is possible to create a virtual acoustic source by focussing sound at a
defined location in space. The sound will then appear to emanate from a focal line - not from the array
itself - allowing for interesting sound design possibilities. Alternatively, dV-ANGLEN can be used to
provide negative tilt for a dV-DOSC array when dV-DOSC is stacked on top of subwoofers.
Just as for V-DOSC, dV-DOSC was designed as a system consisting of identical, vertically-arrayable
enclosures. Individual transducers are physically arranged within each enclosure so as to meet WST
criteria, frequency-band by frequency-band, when the enclosures are arrayed together. Each
enclosure radiates a flat isophasic (constant phase) wavefront, allowing the overall assembly of multiple
enclosures to produce a single extended sound source. Since the angle between adjacent enclosures is
adjustable, the wavefront can be shaped by physically shaping the array. Through successful coupling
over the entire audio frequency range, dV-DOSC produces a consistent wavefront over a large area
with little variation in frequency response and sound pressure level. Since dV-DOSC couples
coherently, enclosures are physically smaller and fewer cabinets are required in comparison with
conventional systems. This makes dV-DOSC very cost effective for touring sound applications where
transport space and handling time means money and for fixed installation where compact size
combined with predictable coverage is important.