L-Acoustics V-DOSC, Operator'S Manual

Page: 148 / 158

L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 148 of 158
APPENDIX 3:
HOW DOES V-DOSC BEHAVE WITH RESPECT TO WST
CRITERIA
The second Wavefront Sculpture Technology criterion: STEP < smallest
λ
/2 over the frequency
range of operation is fulfilled by a V-DOSC array at low and mid frequencies.
With reference to Figure 108,
The 15" speakers are separated by no more than 0,75 m and the crossover frequency is 200Hz,
corresponding to
λ
/2 = 0.85 m.
The 7" speakers are separated by no more than 0.17 m and the crossover frequency is 1300Hz,
corresponding to
λ
/2 = 0.13 m.
Figure 108: Front view of V-DOSC array and vertically stacked DOSC waveguides
We have to fulfill the first WST criterion at higher frequencies, since it is not possible to satisfy
the second criteria as wavelengths are too small to have the acoustic centres of high frequency
compression drivers with less than
λ
/2 separation over the entire HF bandwidth (1.3-18 kHz).
This is achieved by mounting a DOSC waveguide on the exit of each driver – this shapes the
wavefront into a rectangular, constant phase source. Arraying DOSC waveguides and drivers
then creates a flat isophasic ribbon that fulfills the first WST criterion, i.e., the overall radiating
area is more the 80% of the target area provided that the angle is less than 5 degrees between
enclosures.