L-Acoustics V-DOSC, Руководство оператора

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L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 63 of 158
2. V-DOSC COVERAGE MODELING
V-DOSC can be modelled using L-ACOUSTICS proprietary SOUNDVISION or ARRAY2004
software. Alternatively, custom DLLs for V-DOSC and dV-DOSC modeling are available for CATT-
Acoustics or EASE room acoustics modeling sofware.
2.1 COVERAGE IN THE HORIZONTAL PLANE
V-DOSC has a coverage angle of 90° in the horizontal plane from 630 to 12.5k Hz with -6 dB points at
+/- 45° off-axis. Horizontal coverage is independent of both the number of arrayed V-DOSC
enclosures and the vertical configuration of the array. Due to the coplanar symmetric arrangement of
components, the horizontal coverage pattern is symmetrical with respect to the 0° axis.
Note: Although coverage angles are by definition determined by the -6 dB points, for most sound design
applications the -3 dB coverage angle is more representative of the effective coverage of a system. For a V-
DOSC array of arbitrary size and shape, the –3 dB coverage angle is 70° from 630 to 12.5 kHz. This 70°
coverage angle also defines the recommended limit for the relative angle between V-DOSC arrays, for
example, when main L/R FOH V-DOSC arrays are oriented at zero degrees, offstage LL/RR arrays can be
oriented at up to 70° relative to the main L/R arrays while maintaining a 6-7 metre separation between
arrays in order to maximize overall system coverage while reducing the audible effects of interference (see
also 3.1 Multiple Array Concepts).
For sound design purposes, the horizontal coverage of V-DOSC is represented by using an isobaric
(constant sound pressure) curve or isocontour that is obtained by taking the average of individual 1/3
octave polar plots over a 630 to 12.5k Hz bandwidth and then re-formatting the information on a
linear scale. Unlike a standard polar plot, which corresponds to the SPL versus angle referenced to the
on-axis level at a given frequency, the isocontour is more useful for practical coverage prediction.
Note: The 630 – 12.5k Hz bandwidth is selected for the calculation of the V-DOSC isocontour since the
horizontal coverage is stable over this frequency range due to the system’s coplanar symmetry. In addition,
this bandwidth is representative of the perceived intelligibility and clarity of the system.
The horizontal projection of the isocontour can then be used to predict the effective coverage of a V-
DOSC array in the horizontal plane. By overlaying or projecting the isocontour on a plan view of the
venue, the sound designer can adjust the azimuth angle or panning of each array to get the best
coverage results for a given audience layout. Other sound design issues that can be examined using the
isocontour include: optimizing stereo imaging (represented by the amount of overlap between FOH
L/R isocontours); front fill, stereo infill or offstage fill requirements; avoiding wall reflections.
As seen in Figure 43a, at lower frequencies the isocontour becomes more omnidirectional although
there is still pattern control maintained in the forward direction and approximately 20 dB of SPL
rejection behind the array.
For simulation purposes, horizontal isocontour data is provided in the H-ISOCONT sheet in ARRAY
2004. For further details on how to use this data in sound design please see Section 2.3.
Figure 43a: Horizontal V-DOSC isocontour
averaged from 630 Hz - 16 kHz
Figure 43b: Horizontal V-DOSC isocontour
averaged from 32 Hz - 630 Hz