Dv-Dosc Control; (A) General Guidelines Regarding System Protection; (B) Preset Policy - L-Acoustics dV-DOSC Operator's Manual

1.9 dV-DOSC CONTROL

Four digital signal processing units are currently supported and specified by L-ACOUSTICS for
controlling the dV-DOSC system: XTA DP 226, DP 224 and BSS FDS 355 (Omnidrive Compact),
FDS 366 (Omnidrive Compact Plus).
XTA or BSS processors are supplied with proprietary presets that are intended for specific array
configurations. Since the XTA DP 226 is a 2 input by 6 output unit, the DP224 is 2 x 4, the BSS FDS
355 is 3 x 5 and the FDS 366 is 3 x 6, exact internal wiring of your FOH drive rack and digital
processor channel assignments will vary depending on the selected processor and preset. Various
operating modes, processor channel assignments and MULTI line assignments are described in detail
below for the various processors. Carefully consider your flexibility requirements before selecting
the number and type of processors to specify.
NOTE: Whichever processor is used, MULTI line assignments must remain standard to allow for
system compatibility. Failure to follow MULTI standards may result in damage to speaker
components of the V-DOSC system.
ALWAYS REFER TO THE PRESET DESCRIPTION SHEET FOR YOUR PROCESSOR WHEN SELECTING
PRESETS AND CONFIGURING THE DRIVE RACK.

(a) General Guidelines Regarding System Protection

As supplied by L-ACOUSTICS, limit thresholds for all dV-DOSC presets for both XTA and BSS
processors are set at +7 dBu (100 Hz HPF) or +5 dBu (75 Hz HPF) for the low section and +4 dBu
for the high section. These limit thresholds are set based on the power handling specifications of
each section. In addition to crossover limiters, amplifier power ratings must be correctly matched to
loudspeaker's power handling capabilities and amplifiers must have 32 dB gain. For L-ACOUSTICS
LA 24 and LA 48 amplifiers please refer to tables 6 and 7 to determine the correct MLS switch
settings required for power matching.
When further system protection is desirable, low and high section limit thresholds can be reduced up
to an additional 3 dB below the initial values (i.e., +4 / +2 dBu for the low section, +1 dBu for the
high section). Exact settings will depend on individual engineer preferences and the type of music or
application which, in turn, determines how hard the system is being operated and how much
headroom is desired.

(b) Preset Policy

dV-DOSC and V-DOSC presets are provided as a reference for all Qualified V-DOSC Technicians
and Certified V-DOSC Engineers. According to L-ACOUSTICS policy, key parameters are software
protected and preset data is not freely communicated in order to preserve quality control,
confidentiality and to maintain the integrity of L-ACOUSTICS system presets.
A lot of engineering and real world testing goes into determining optimum dV-DOSC presets –
detailed polar measurements and weighted spatial averaging are used to determine component
equalization, crossover points and crossover filter slopes, for example. As a result, dV-DOSC presets
give the user an optimum starting point – system tuning should be done using band attenuation,
accurate subwoofer time alignment and system equalization – not by altering crossover presets for
the following reason:
Without proper instrumentation and spatial averaging, adjustments made at one location (e.g. the
mix position) are not optimum at all other locations within the defined coverage region of the
system. When made by ear, such adjustments are often misguided – the user may be in a local room
mode (low frequency pressure maximum or minimum) and/or may be hearing a cancellation or
addition due to crossover misalignment that sounds good at that specific location but what about all
others? Meanwhile, the same result could have been achieved while preserving the power response
of the system (and satisfaction of WST criteria) by using the correct crossover preset and a simple
equalization cut or correct time alignment of subwoofers ...
dV-DOSC dV-SUB Manual V2.0 Nov 2001 38