L-Acoustics V-DOSC, Operator'S Manual

Page: 149 / 158

L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 149 of 158
APPENDIX 4:
HOW DOES THE DOSC WAVEGUIDE WORK?
The DOSC waveguide is the result of careful analysis of the wave path from the exit of a
compression driver, through the waveguide and the resulting wavefront shape at the exit of the
device.
Figure 109: Horn Generated Wavefronts
With respect to Figure 109, the wavefront emerging from a horn is the result of constant time
arrivals for all possible wave paths radiated by the driver exit. The two examples shown in
Figure 109 produce more or less curved wavefronts that obviously cannot meet the first WST
criterion.
Figure 110: DOSC Waveguide – Internal Section
By comparison, the DOSC waveguide acts as a time alignment plug, delaying the arrival times of
every possible wave path to be the same value at the rectangular exit of the device. The internal
plug is a truncated conical piece that looks like a "tomahawk". This plug and its outer housing are
precisely constructed according to specific ratios between depth, height and cone angle in order
to produce a flat constant phase wavefront. Tight manufacturing tolerances are obtained
through the use of computer aided design and manufacturing (CAD/CAM) techniques in the
fabrication of the DOSC waveguide. As shown in the AES preprint entitled ''Wavefront Sculpture
Technology'', the deviation from a flat wavefront must be less than
λ
/4 at the highest operating
frequency - this corresponds to less than 5 mm of curvature at 16 kHz and experiments have
shown that the DOSC waveguide provides less than 4 mm of curvature at this frequency.
DOSC waveguide technology is patented on an international basis.
(n°0331566 in Europe, n°5163167 in North America).