L-Acoustics dV-DOSC, Operator'S Manual

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dV-DOSC dV-SUB Manual V3.0 June 2005
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section operating bandwidths, i.e., the 24 dB per octave low pass filter for the SB218 or SB118
generates a phase shift of 180°). The X preset takes full advantage of dV-SUB resources and provides
maximum sub/low output.
As an alternative to the X preset, the flown dV-DOSC/dV-SUB system can be operated as a 3-way
stereo system using either dV 3W 80 dV-SUB, dV 3W 120 dV-SUB, dV 3W 200 dV-SUB presets and
aux sub drive performed using SB218 DELAY ARC 80 Hz or SB218 LCR 80 Hz presets (subs with
negative polarity). This approach is particularly useful when implementing delay processed subwoofer
arrays, LCR subwoofer arrays or for larger subwoofer array configurations where it is desirable to
dedicate a DSP unit to subwoofer drive for additional control and flexibility.
3.4.6 Large Format Flown/Ground Stacked Subwoofer Configurations
For larger configurations, it is important to ensure that the flown dV-SUB array does not physically
interfere with dV-DOSC array coverage. Techniques for minimizing this effect are shown in Figure 69
where the flown L/R system consisits of 18+18 dV-DOSC enclosures and 6+6 dV-SUB (3:1 ratio).
In Fig. 69a. the dV-SUB array is tilted downwards (by the relative action of front and rear motors for a
2-point hang, or by using holes 6,7 or 8 for a single point hang). In addition, the trim height is carefully
selected and rigging points physically offset relative to the dV-DOSC array in order to prevent lower
dV-DOSC enclosures from firing into lower dV-SUB enclosure walls. Standard 4-way presets (INFRA
or X) can be used for this configuration.
In Fig. 69b, the dV-SUB array is flown behind the dV-DOSC array. Pre-delay is applied to the dV-
DOSC array in order to time align the two flown systems and the 3-way stereo preset dV 3W 80 dV-
SUB is recommended in conjunction with aux sub drive for the ground stacked subwoofers (X mode,
i.e., 80 Hz low pass filter, negative polarity for SB118 or SB218 subwoofers).
In Fig. 69c, individual L/R dV-SUB arrays are split into 2 arrays of 3 and flown in a coplanar
configuration on either side of dV-DOSC. Trim height is set to align the dV-SUBs with the flattest part
of the array in order to minimize physical interference and optimize time alignment aspects. Standard
4-way mode presets can be used for this configuration.
The choice between the options pictured in Figure 69 will largely depend on the size and shape of the
dV-DOSC array. For example, for flat open air festival applications, normally the dV-DOSC array is flat
at the top, has reduced overall curvature and is oriented downwards so Fig. 69a would be
appropriate. Options shown in Figs. 69b and 69c would be more suitable for arena sound
reinforcement.
(a) Offstage dV-SUB array
(b) dV-SUB flown behind dV-DOSC
(c) Coplanar dV-SUB arrays
Figure 69: Flown L/R dV-SUB options for larger system configurations