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A line array is a loudspeaker system that is made up of a number of usually identical loudspeaker elements mounted in a line and fed in phase, to create a near-line source of sound. The distance between adjacent drivers is close enough that they constructively interfere with each other to send sound waves farther than traditional horn-loaded loudspeakers, and with a more evenly distributed sound output pattern. Line arrays can be oriented in any direction, but their primary use in public address is in vertical arrays which provide a very narrow vertical output pattern useful for focusing sound at audiences without wasting output energy on ceilings or empty air above the audience. A vertical line array displays a normally wide horizontal pattern useful for supplying sound to the majority of a concert audience. Horizontal line arrays, by contrast, have a very narrow horizontal output pattern and a tall vertical pattern. A row of subwoofers along the front edge of a concert stage can behave as a horizontal line array unless the signal supplied to them is adjusted (delayed, polarized, equalized) to shape the pattern otherwise. Loudspeakers can be designed to be arrayed horizontally without behaving as a horizontal line source.〔(L-Acoustics Line Source Products Page ); (L-Acoustics Technical bulletin )〕 Modern line arrays use separate drivers for high-, mid- and low-frequency passbands. For the line source to work, the drivers in each passband need to be in a line. Therefore, each enclosure must be designed to rig together closely to form columns composed of high-, mid- and low-frequency speaker drivers. Increasing the number of drivers in each enclosure increases the frequency range and maximum sound pressure level, while adding additional boxes to the array will also lower the frequency in which the array achieves a directional dispersion pattern. The large format line array has become the standard for large concert venues and outdoor festivals, where such systems can be flown (rigged, suspended) from a structural beam, ground support tower〔http://www.jthomaseng.com/towers.htm Ground support tower〕 or off a tall A-frame truss tower.〔()〕 Since the enclosures rig together and hang from a single point, they are more convenient to assemble and cable than other methods of arraying loudspeakers. The lower portion of the line array is generally curved backward to increase dispersion at the bottom of the array and allow sound to reach more audience members. Typically, cabinets used in line arrays are trapezoidal, connected by specialized rigging hardware.〔SoundOnSound Live magazine, Issue 7, March 2006〕 == History == The line array effect of the narrowing of the beam with increasing frequency was first demonstrated by acoustical pioneer Harry Olson.〔http://www.livesoundint.com/archives/2003/sept/jbl/jbl.php JBL's development team talks about line array concepts〕 He published his findings in his 1957 text, ''Acoustical Engineering''.〔http://www.meyersound.com/support/papers/line_array_theory.htm〕 Olson used line array concepts to develop the column speaker in which vertically aligned drivers in a single enclosure produced mid-range output in a wide horizontal and narrow vertical pattern. Line arrays have been around for over half a century but until recently most were voice range only. The application for these were for highly reverberant spaces where a narrow vertical design kept from exciting the reverberant field.〔http://www.prosoundweb.com/article/everything_you_wanted_to_know_about_line_arrays_and_thanks_for_asking/P3/〕 A multi-band line array elements in a horizontally oriented enclosure was suggested by Joseph D'Appolito in 1983.〔http://www.livesoundint.com/archives/2003/sept/jbl/jbl.php JBL's development team talks about line array concepts.〕 However, it was L-Acoustics' V-DOSC line array in the mid-1990s that would show the concert world that a more level and smoother frequency response can come from fewer boxes in a line array. As soon as people realized that there was no destructive interference in the horizontal plane and waves combine mostly in phase in the vertical plane, the race was on for loudspeaker manufacturers.〔http://www.prosoundweb.com/article/everything_you_wanted_to_know_about_line_arrays_and_thanks_for_asking/P3/〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「line array」の詳細全文を読む スポンサード リンク
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