L-Acoustics ARCS, Руководство оператора

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L-ACOUSTICS ARCS Manual V2.0 2/13/2003
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FLOWN/STACKED CENTRE FILL
Due to its compact size, modular horizontal coverage and generous asymmetrical vertical coverage,
ARCS is highly suitable for center fill applications in theatre or for concert sound reinforcement when
the stage is wide and main left/right array separation is more than 20 meters. An inverted center
cluster array of 4-6 ARCS enclosures is very effective in these situations - the number of enclosures
required depends on the horizontal coverage requirements (which in turn depends on the separation
between main left/right arrays and how the main arrays are focused in the near field). The trim height
and tilt of the ARCS center fill array depends on the closest distance to be covered which is in turn
determined by the distance to the first rows of the audience area. L-ACOUSTICS' ARRAY software is
very useful for predicting vertical coverage requirements (see ARRAY AIMING), allowing the sound
designer to quickly determine the necessary trim height and ARCS array tilt angle. Once rigging
parameters are determined, the ARCS Rigging Reference Chart in Section 5 allows for efficient
installation.
As an alternative to flown center fill, ARCS can be stacked on top of a central line array of SB218
subwoofers (or any other object of suitable height) provided that the height of the HF section is
suitable for audience coverage. Typically, a stacking height of at least 2 meters is recommended and
ARCS should be inverted so that HF energy is projected down into the audience. However, clearance
under the stage lip and audience sightlines are often important considerations for stacked center fill. If
sufficient height cannot be obtained then ARCS can be used in the horizontal orientation as a
distributed front fill system.
STACKED STEREO INFILL
Stacked stereo infill systems can be implemented using ARCS enclosures either located onstage or
stacked on top of L/R subwoofer arrays. It is always a good idea to keep ARCS physically as close as
possible to the subwoofers in order to improve sonic integration between the fill system and the
subwoofers plus to reduce proximity effects for the audience located close to the subwoofers. For
smaller set designs, it can also be an option to place stereo front-fill ARCS close to the subwoofers
employed for onstage side-fill monitors. As for stacked center fill applications, the height of the HF
section should be optimized to suit the audience seating area with special attention paid to the first
few rows. Typically, a stacking height of at least 2 meters is recommended and ARCS should be
inverted so that HF energy is projected down into the audience. If possible, use distance-attenuation
loss to your advantage and try to move ARCS as far upstage as possible in order to reduce the
increase in SPL over the first few rows relative to the audience further back in the coverage region.
For stereo front fill applications 4 ARCS enclosures provide 90 degree horizontal coverage and thus
provide a good match to the coverage of the main V-DOSC arrays.
Single ARCS enclosures can also be used in the horizontal orientation for stereo front fill. In this case,
the central axis of the loudspeaker should be aimed towards the rearmost part of the audience area to
be covered. Typically, this means that ARCS will require rear blocking so that the enclosure points
down into the audience slightly. In the horizontal orientation, coverage is 60° (asymmetrical) and
normally ARCS is oriented with the 40° angle directed onstage (i.e., toed inwards with the logos of the
left and right enclosures oriented in the offstage direction).
OFFSTAGE FILL
When the horizontal coverage of the main left/right arrays is not sufficient to cover the entire
audience area, single or double row ARCS arrays are effective for offstage fill. Typically, throw
distance requirements are shorter and vertical coverage angles are greater making ARCS a good
solution for this application. OEM factory presets for ARCS have been specifically engineered to
provide a sonic signature that is compatible with V-DOSC and the modular horizontal coverage of
ARCS allows for precise focus of energy in the areas where offstage coverage is required. ARRAY
software provides a useful tool for examining the vertical section cutview to determine ARCS array
trim height and overall tilt, while the horizontal V-DOSC isocontour is effective in determining the