Left/Centre/Right Configurations; Figure 73: Electronic Delay Processing Examples Using A 4- Or 6-Channel Dsp - L-Acoustics dV-DOSC Operator's Manual

An EXCEL spreadsheet tool to perform delay and offset calculations is available in ARRAY2004 (SUB
ARC). Several examples are given in Figure 73 (for further details on the SUBARC sheet please see the
V-DOSC manual).
HORIZONTAL SB218 (16 TOTAL)
T4 T3 T2
T4 T3 T2
T1 = 0 msec
T2 = 1.167 msec
T3 = 3.036 msec
T4 = 5.495 msec
VERTICAL SB218 (8 TOTAL)
T4 T3 T2 T1 T1 T2 T3 T4
T1 = 0 msec
T2 = 0.493 msec
T3 = 1.282 msec
T4 = 2.320 msec

Figure 73: Electronic delay processing examples using a 4- or 6-channel DSP

3.5.3 LEFT/CENTRE/RIGHT CONFIGURATIONS

When properly time aligned, LCR subwoofer arrays can provide more even low frequency impact and
horizontal coverage combined with reduced centre build up in comparison with L/R subwoofer arrays.
In effect, LCR subwoofer arrays act as an approximation to an electronic delay processed horizontal
line array of subwoofers (Section 3.5.2). Since time alignment must be considered in both vertical and
horizontal planes, LCR subwoofer arrays provide more flexibility in comparison with L/R ground
stacks - especially given the additional contribution of flown dV-SUB arrays.
Figure 74(a) shows a ground stacked LCR configuration. In this case, time alignment should be
performed as follows: (i) time align L with respect to C with the measurement microphone on-axis to
L at a distance where the SPL from C and L arrays is identical; (ii) time align dV-DOSC/dV-SUB FOH L
with respect to L with the measurement microphone located between FOH L dV-SUBs and ground
stacked L subwoofers at a distance where the SPL from the low section of the flown system equals
the SPL from the ground stacked subwoofers; (iii) duplicate time alignment settings for R subwoofers
and FOH R; (iv) if applicable, time align LL and RR arrays to L and R, respectively, performing
measurements in a representative location where main and off-stage fill system coverage overlaps.
Figure 74(b) shows a variation on the ground stacked LCR system of Fig. 74(a). For this example, the
L/R subwoofers are stacked 4 high (to provide a location for stacked stereo infill dV-DOSC or ARCS
enclosures) and the C position is split into 2 points to provide a location for centre stereo infill
enclosures (for example, ARCS or MTD/XT coaxial enclosures). Provided that the separation
between the split C subwoofer arrays is less than 4.5-6 metres, they will also act as a centre channel in
conjunction with the ground stacked L/R vertical columns to create an overall LCR configuration.
Figure 74(c) shows a variation on the Fig 74(b) configuration where the L/R SB218 subwoofer arrays
are flown offstage of the FOH L/R dV-DOSC/dV-SUB arrays.
Figure 74(d) shows a hybrid ground stacked LR / flown C configuration. In this case, a stereo infill
system (using ARCS or dV-DOSC, for example) can be combined with the ground stacked LR
subwoofer arrays and a centre cluster downfill system integrated with the flown C subwoofer array.
Time alignment should be performed in multiple steps: (i) time align L with respect to C with the
measurement microphone in between L and C at a distance where the SPL from C and L arrays is
identical; (ii) time align dV-DOSC/dV-SUB FOH L with respect to L subwoofers with the
measurement microphone located midway between FOH L and ground stacked L subwoofers at a
distance where the SPL from the low section of the flown system equals the SPL from the ground
stacked subwoofers; (iii) duplicate the time alignment settings for R subwoofers and FOH R; (iv) if
dV-DOSC dV-SUB Manual V3.0
T1 T1 T2 T3 T4
T1 T1 T2 T3 T4
HORIZONTAL SB218 (24 TOTAL)
T6 T5 T4 T3 T2
T6 T5 T4 T3 T2
T1 = 0 msec
T2 = 0.761 msec
T3 = 2.052 msec
T4 = 3.863 msec
T5 = 6.088 msec
T6 = 8.634 msec
VERTICAL SB218 (12 TOTAL)
T6 T5 T4 T3 T2 T1 T1 T2 T3 T4 T5 T6
T1 = 0 msec
T2 = 0.322 msec
T3 = 0.867 msec
T4 = 1.632 msec
T5 = 2.572 msec
T6 = 3.649 msec
June 2005
T1 T1 T2 T3 T4 T5
T1 T1 T2 T3 T4 T5
94
T6
T6