L-Acoustics V-DOSC, Operator'S Manual

Page: 123 / 158

L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 123 of 158
SAFETY RULES
CAUTION: THE RIGGING SYSTEM IS RATED FOR A MAXIMUM OF 16 V-DOSC, 15 V-
DOSC + 3 dV-DOSC or 14 V-DOSC + 6 dV-DOSC.
All rigging should be performed by certified, trained personnel.
Proper chain motor installation and operation is absolutely necessary under all circumstances.
L-ACOUSTICS recommends the use of safeties at all times.
Chain motor ratings for each fly point are as follows:
0.5T motor per point for a 4-enclosure array;
1.0T motor per point for a 5- to 10-enclosure array;
2.0T motor per point for a 11- to 16-enclosure array.
For additional safety factor when flying 11-16 enclosure arrays, a bridled hang from the front and
rear corner rigging points should be performed using two steel slings, four shackles and one
pear ring (front and rear).
Always refer to the MECHANICAL DATA in ARRAY 2004 or SOUNDVISION to ensure that
safe rigging conditions apply before installation.
Ensure that the immediate area is clear of people and obstacles whenever raising or lowering
the array. Announce (in a loud voice) whenever the array is being moved to get people’s
attention. Always look up while moving the array to be sure that movement remains unimpeded
and to check cable tension. Once flown to trim and correctly angled, remove the motor control
cables so that the array cannot be tampered with by unauthorized people.
Always cover motors with plastic in outdoor installations where motors may be exposed to rain.
Do not overtighten ratchet straps, especially if the array is tilted upwards.
5. V-DOSC SYSTEM OPERATION
WARNING: The V-DOSC system is capable of producing high sound pressure levels. Hearing loss
or damage can occur with prolonged exposure to high SPLs. Please operate your system
responsibly at all times. An SPL meter on the mix console is highly recommended as a reference.
Prior to describing system operation and tuning procedures, subjective criteria and system setup
objectives are first considered.
5.1 SYSTEM TONAL BALANCE
V-DOSC and dV-DOSC presets have been specifically engineered to provide an excellent starting
point for system tuning. Frequency response is flat between 300 Hz - 4 kHz and from 40 – 160
Hz, a 10 dB low frequency contour is built into the preset. At higher frequencies, the response is
either flat (LO presets) or has additional high frequency shelving (HI presets).
It is always a good idea to set the ratios between mid/high, low and sub sections using the output
channel gains of the DSP before proceeding to perform detailed measurements and equalization.
Output gain scaling sets the tonal balance of the system by compensating for the size of the array
(low end coupling) and the V-DOSC:SB218 cabinet ratio (low/sub coupling). In general, as the
array size doubles, the low end increases by 6 dB and the mid/high response by 3 dB so the low
frequency contour for V-DOSC (without subwoofers) scales as follows: 1 V-DOSC (10 dB); 2 V-
DOSC (13 dB), 4 V-DOSC (16 dB), 8 V-DOSC (19 dB), 16 V-DOSC (22 dB). As a result, for
larger V-DOSC arrays (12-16 enclosures) the mid and high sections can both be increased by 3-6
dB (or the low section attenuated) to compensate for the enhanced low end coupling that occurs.
Output gain scaling should also be performed to compensate for the V-DOSC:SB218 cabinet ratio.
Standard output gains apply to a 3:2 V-DOSC:SB218 ratio; for a 2:1 ratio, subwoofer gain should
be 2 dB; for a 1:1 ratio, the low section output gain should be 4 dB (see Section
1.15 for further details).