2. XLC Rigging and Flying Techniques
2.1 Array Considerations
The XLC loudspeaker systems have been specifically designed to construct acoustic line-arrays. Line-array systems typically consist of independent columns of loudspeaker enclosures. The most common implementation would be a stereo sound reinforcement system with two columns (left and right). Additional columns of loudspeakers are sometimes added to cover different seating sections of a venue – seating areas that wrap around the side or back of a stage, for example.
The XLC line arrays will consist of columns of XLC-127 or XLC-127+ 120°H x 7°V full-range systems. The exact number of XLC loudspeaker systems in a column will vary depending on the vertical acoustic coverage required for the specific venue. Furthermore, the relative vertical angles between the boxes will also depend on the venue’s acoustic coverage requirements. (Acoustic design techniques are outside the scope of this document and the reader is directed to the XLC modeling software available from the Electro-Voice website for acoustic design assistance.) It is also possible to construct subwoofer line arrays using the XLC-118 systems.
Although the full-range XLC loudspeaker systems shown in Figure 1 are not physically symmetrical, their acoustical polar responses are substantially symmetrical because the high- frequency sections are in the center of the enclosures. Thus, stereo left and right arrays, or left- center-right arrays may be constructed with the loudspeakers in their normal right-side-up orientation as shown in Figure1.
XLC-127 AND XLC-127+ LOUDSPEAKER SYSTEMS SHOULD NOT BE MIXED IN THE SAME LINE-ARRAY COLUMN BECAUSE THEIR ACOUSTIC TIME AND PHASE RESPONSE IS DIFFERENT. BOTH THE XLC-127 AND XLC-127+ HAVE AN INTERNAL CROSSOVER THAT MAY BE SWITCHED IN OR OUT, ALLOWING THE SYSTEMS TO BE TRIAMPED OR BIAMPED. TRIAMPED AND BIAMPED SYSTEMS MUST NOT BE MIXED IN THE SAME LINE-ARRAY COLUMN BECAUSE THEIR ACOUSTIC TIME AND PHASE RESPONSE IS DIFFERENT.
2.2 Rigging an Array Using the XLC Front Dollies
The XLC loudspeaker systems have front-mount dollies available for transportation. The XFD-118 is a front dolly for the XLC-118 subwoofer, while the XFD-127 is a front dolly for XLC-127 and XLC-127+ full-range systems. Each side of the dolly has a quick-release clip that latches to the rigging frame on the side of the enclosure. Figure 6 illustrates the technique used to construct a loudspeaker array with enclosures transported on front dollies.
First, several enclosures are rolled into position for an array, as shown in Figure 6a. The enclo- sures should be pushed tight against each other. Next, take the front button bar that is retracted inside from the rigging tube of one enclosure and slide it into the front rigging tube of the adjacent enclosure, as shown in Figure 6b. To release the bar from its locked position in the first enclosure, push in the spring-loaded blue button until it can clear the round cutout in the side of the rigging tube. While holding down the button, grab the button bar knob that is protruding through the rear of the rigging tube and slide the entire button-bar assembly into the front rigging tube of the adja- cent enclosure.
