Introduction; Wavefront Sculpture Technology™ Fundamentals; The Sound Reinforcement Problem - L-Acoustics dV-DOSC Operator's Manual

0. INTRODUCTION

The small ''d'' in dV-DOSC refers to the mathematical terminology for the derivative function since
dV-DOSC is a derivative of V-DOSC. dV-DOSC provides the same benefits of Wavefront Sculpture
Technology as V-DOSC except in a much smaller format.
We hope this manual will help you to appreciate why and to understand the basic principles behind
how the dV-DOSC system works. Understanding these principles will help you to optimally use dV-
DOSC and dV-SUB in sound design – whether for touring or fixed installation. Understanding the
concepts behind dV-DOSC and Wavefront Sculpture Technology are just as important as learning
the many operational details related in this manual – the more you understand the big picture, the
more effectively you will use the system.
As you will see, dV-DOSC is a complete system approach – starting from the basic question of how
to effectively couple sound sources then including all aspects of sound design, performance
prediction, system installation, rigging, cabling, signal distribution, digital control and tuning. This
turnkey system approach allows for accurate and predictable results, however, in order to achieve
the best results you need to understand the concepts behind how the system works.
Apart from sound quality, the system design approach and ergonomics, there are many benefits to
dV-DOSC. Many of you readers are already aware of these benefits; otherwise they will become
apparent throughout the course of this manual.
0.1 WAVEFRONT SCULPTURE TECHNOLOGY™ FUNDAMENTALS

The Sound Reinforcement Problem

The trend in sound reinforcement has been to increase both the actual SPL during concerts and the
size of the audience to be covered. This leads to an increased number of loudspeakers since more
powerful single loudspeakers would reach such sizes and weights that their transport, handling and
installation would simply not be feasible.
In practice, conventional loudspeakers are assembled in a fan-shaped array following the angle
determined by the horizontal directivity of each enclosure in an attempt to reduce overlapping
zones that cause destructive interference. With this type of arrangement, the optimum clarity
available in one direction can only be provided by the individual enclosure facing in this direction.
Attempts at "flattening the array" in order to achieve greater throw and higher sound pressure levels
results in severe interference in an uncontrolled way, affecting coverage, directivity control,
intelligibility and overall sound quality. Even when arrayed according to specification (always an
''optimum'' compromise), the sound waves radiated by individual loudspeakers do not couple
coherently thus the conventional system approach is fundamentally flawed. Furthermore, the chaotic
sound fields created by interfering sound sources waste acoustic energy, thus requiring more power
than a single, coherent source would in order to achieve the same sound pressure level.
To illustrate this, consider what happens when we throw pebbles in the water. If we throw one
pebble into the water, we can see circular waves expanding from the place where it disturbed the
surface. If we throw a handful of pebbles, we observe a chaotic wavefield. If we throw a larger
stone, with total size and weight equivalent to the handful of pebbles then we see a circular wave as
was obtained with the single pebble, except now with much larger amplitude. If all of the individual
pebbles of the handful could be glued together, this would provide the same effect as the larger
stone...
This illustrates the thinking behind dV-DOSC and V-DOSC: if we can build a single sound source
from a number of individual speakers that can be separated for transport and handling, then we have
achieved our goal, i.e., to provide a totally coherent, predictable wavefield.
dV-DOSC dV-SUB Manual V2.0 Nov 2001 8