(1) A piece of material that plays over and over. In a sampler, loops are used to allow samples of finite length to be sustained indefinitely. See also sustain loop, release loop.
(2) A section of tape with the two free ends joined, used for creating repeated sounds. Tape loops were used in the first delay units, where a short tape circulated around a system consisting of a record head followed by a series of replay heads to pick up the increasingly delayed signal (as well as an increasing proportion of noise).
(3) In tape recorders equipped with zero-locators, a transport operating mode in which the engineer has designated a starting and ending point, either in tape time or SMPTE time code, and instructed the locator and machine to play the enclosed tape segment repeatedly, rewinding to the starting point each time the end point is reached. Most video interlock devices can be programmed to cause both video and any synchronized audio decks to repeatedly reproduce a loop of picture and its corresponding sound. The engineer may place the audio or video deck into record mode during a section of each repeat of the loop in order to replace dialog or other sync sound, or to perform insert edits.
(4) In cameras and projectors, a slack section of film located just before and after the gate. The loop prevents tearing of the film as it passes from continuously turning sprockets to the intermittent movement of the supply reel.
(5) A wire or cable system which has at least two ends joined together, usually creating ground loops.
(6) An electronic connection where a device has a circuit from its output back to its input. See feedback.