L-Acoustics ARCS Operator's Manual

Contents

L-Acoustics ARCS Operator's Manual Manual pdf 33 page image

L-ACOUSTICS ARCS Manual V2.0 2/13/2003 32FLOWN/STACKED CENTRE FILLDue 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 whenthe stage is wide and main left/right array separation is more than 20 meters. An inverted centercluster array of 4-6 ARCS enclosures is very effective in these situations - the number of enclosuresrequired depends on the horizontal coverage requirements (which in turn depends on the separationbetween main left/right arrays and how the main arrays are focused in the near field). The trim heightand tilt of the ARCS center fill array depends on the closest distance to be covered which is in turndetermined by the distance to the first rows of the audience area. L-ACOUSTICS' ARRAY software isvery useful for predicting vertical coverage requirements (see ARRAY AIMING), allowing the sounddesigner to quickly determine the necessary trim height and ARCS array tilt angle. Once riggingparameters are determined, the ARCS Rigging Reference Chart in Section 5 allows for efficientinstallation.As an alternative to flown center fill, ARCS can be stacked on top of a central line array of SB218subwoofers (or any other object of suitable height) provided that the height of the HF section issuitable for audience coverage. Typically, a stacking height of at least 2 meters is recommended andARCS should be inverted so that HF energy is projected down into the audience. However, clearanceunder the stage lip and audience sightlines are often important considerations for stacked center fill. Ifsufficient height cannot be obtained then ARCS can be used in the horizontal orientation as adistributed front fill system.STACKED STEREO INFILLStacked stereo infill systems can be implemented using ARCS enclosures either located onstage orstacked on top of L/R subwoofer arrays. It is always a good idea to keep ARCS physically as close aspossible to the subwoofers in order to improve sonic integration between the fill system and thesubwoofers plus to reduce proximity effects for the audience located close to the subwoofers. Forsmaller set designs, it can also be an option to place stereo front-fill ARCS close to the subwoofersemployed for onstage side-fill monitors. As for stacked center fill applications, the height of the HFsection should be optimized to suit the audience seating area with special attention paid to the firstfew rows. Typically, a stacking height of at least 2 meters is recommended and ARCS should beinverted so that HF energy is projected down into the audience. If possible, use distance-attenuationloss to your advantage and try to move ARCS as far upstage as possible in order to reduce theincrease 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 thusprovide 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 tobe covered. Typically, this means that ARCS will require rear blocking so that the enclosure pointsdown into the audience slightly. In the horizontal orientation, coverage is 60∞ (asymmetrical) andnormally ARCS is oriented with the 40∞ angle directed onstage (i.e., toed inwards with the logos of theleft and right enclosures oriented in the offstage direction).OFFSTAGE FILLWhen the horizontal coverage of the main left/right arrays is not sufficient to cover the entireaudience area, single or double row ARCS arrays are effective for offstage fill. Typically, throwdistance requirements are shorter and vertical coverage angles are greater making ARCS a goodsolution for this application. OEM factory presets for ARCS have been specifically engineered toprovide a sonic signature that is compatible with V-DOSC and the modular horizontal coverage ofARCS allows for precise focus of energy in the areas where offstage coverage is required. ARRAYsoftware provides a useful tool for examining the vertical section cutview to determine ARCS arraytrim height and overall tilt, while the horizontal V-DOSC isocontour is effective in determining the