L-Acoustics V-DOSC - Flown V-DOSC and Ground Stacked Subwoofers; Time Alignment for Flown;Stacked Subwoofer Systems

L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 93 of 158
3.4.1 Flown V-DOSC and Ground Stacked Subwoofers
Subwoofers are usually ground stacked to take advantage of the 6 dB SPL enhancement that is
obtained due to floor coupling (effectively, there is a mirror image that doubles number of
subwoofers). Various flown V-DOSC and ground stacked subwoofer combinations are shown in
Figure 69 (these configurations are discussed in more detail in Subwoofer Arraying Techniques).
Left/Right Subwoofer Configuration
Central Subwoofer Line Array
LCR Configuration
Figure 69: Flown V-DOSC and ground stacked subwoofer configurations
As illustrated in Figure 70, for flown V-DOSC and ground stacked subwoofer configurations, time
alignment of subwoofers is required due to the geometric path difference between the two systems.
The distance from the measurement microphone to the subwoofers is d
SUB
while the distance to the
flown V-DOSC system: d
V-DOSC
= d
SUB
+ PATH DIFFERENCE. Delaying the subwoofers by the
geometric path difference is necessary to time align the subwoofers at the reference position.
Note: The geometric path difference should be added to the pre-alignment delay that already exists in the
standard presets (see Section 1.15 for further details).
Figure 70: Flown V-DOSC and ground stacked subwoofer time alignment