L-ACOUSTICS XT Manual V1.1
2/11/2003
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4.5.3 COMPLEMENTARY FILL
For large-scale sound reinforcement (typically when V-DOSC, dV-DOSC or ARCS are used as the
main FOH system), XT enclosures can be used for distributed front fill (ground stacked), flown center
cluster downfill, stereo in-fill, offstage fill or as distributed delays. The number of potential uses for
112XT or 115XT enclosures for fill applications is only limited by your imagination.
In all cases, proper time alignment of fill systems with respect to the main L/R FOH system is essential
for obtaining optimum results. Similarly, pre-delay to time align the overall sound reinforcement
system (main L/R FOH plus fill systems) with the energy generated on stage is also an important
consideration for the first 10 rows of the audience. WINMLS, SMAART or SPECTRAFOO are cost-
effective measurement tools for performing time alignment that are recommended.
FLOWN CENTER CLUSTER
Due to their compact size, point source behavior and generous coverage, XT enclosures are highly
suitable for center cluster applications. Typically this will be necessary when the stage opening is wide
and the left/right FOH system separation is more than 20 meters. Apart from coverage issues, image
localization is an important consideration (particularly for theatrical installations) and careful time
alignment plus attenuation can significantly improve subjective localization for the audience to the
onstage performers. In some cases, two XT enclosures can be arrayed vertically as a center cluster
and considered as separate floor and balcony systems with different signal processing (time delay,
level, equalization) applied to the individual XT enclosures in order to optimize image localization for
the two separate audience areas. Trim height and tilt of an XT center cluster fill system will depend
on the distance to the first rows of the audience and on the height of the proscenium opening.
DISTRIBUTED FRONT FILL
As an alternative (or complement) to a flown center cluster, XT enclosures can be stacked on top of a
central line array of subwoofers (or any other object of suitable height) provided that the height of the
HF section is appropriate for audience coverage. Typically, a stacked height of at least 1-2 meters is
recommended in order to reduce audience shadowing effects and whether the audience is seated or
standing should also be considered. In addition to these issues, sightlines and clearance under the stage
lip are also important considerations for a distributed front fill system and when space is at a premium,
the MTD108a (or dV-DOSC) can be considered as alternatives.
As for overhead distributed or delay systems, the optimum spacing between XT enclosures will
depend on the coverage angle of the enclosure (90 deg for 112XT, 80 deg for 115XT) and the
distance to the first members of the audience. Center-to-center overlap will provide the most uniform
coverage and separate time alignment delay taps for front fill enclosures can further assist in improving
image localization.
STEREO INFILL
Stacked stereo infill systems using XT enclosures either located onstage or stacked on top of L/R
ground stacked subwoofer arrays can also be effective for front fill purposes. It is always a good idea
to keep XT enclosures physically as close as possible to the subwoofers in order to improve sonic
integration between the fill system and the subwoofers plus to reduce low frequency proximity effects
for the audience located close to the subwoofers (i.e., it’s good to give the audience some high end to
help offset all that sub energy!). For smaller set designs, it can also be an option to place stereo front-
fill XT enclosures close to the onstage side-fill monitoring system.
As for distributed front fill applications, the height of the HF section should be optimized to suit the
audience seating area in order to reduce shadowing effects. Special attention should be paid to the
first few rows and a stacked height of at least 1-2 meters is recommended. If possible, use distance-
attenuation loss to your advantage and move XT enclosures 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.
Summary of Contents for 112XT
Page 1: ...Version 1 1 February 2003 L ACOUSTICS XT LINE 112XT 115XT OPERATOR MANUAL...
Page 3: ...L ACOUSTICS XT Manual V1 1 2 11 2003 2...
Page 45: ...L ACOUSTICS XT Manual V1 1 11 02 03 44 Figure 21 112XT Line Drawing...
Page 49: ...L ACOUSTICS XT Manual V1 1 11 02 03 48 Figure 26 115XT Line Drawing...
