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tape recorder

tape recorder, device for recording and replaying of sound, video, and digital information on plastic (usually polyester) or paper tape. The tape is coated with fine particles of a magnetic substance, usually an oxide of iron, cobalt, or chromium. The coating is normally held on the tape with a special binder. Tape recorders can store many different forms of information. The first tape recorders were used to store audio information. In audio recorders, the sound to be recorded is picked up by a device such as a microphone , and transformed into an electric current. The current is fed to a transducer in the recording head of the tape recorder, which converts it into corresponding magnetic flux variations that magnetize the particles on the tape. Tape recorders always require that the recording media and the recording or playback tape heads move with respect to each other. During playback the tape passes over the playback head (often the same one used for recording) and the tape's magnetic field induces a current in the transducer. The current is then amplified and used to reproduce sound through a loudspeaker . Tape hiss, sound composed of high frequencies picked up at random during recording, is suppressed by several systems, among them Dolby, Dolby-B, Dolby-C, and dbx. Digital audio tape (DAT) and digital compact cassette (DCC) recorders transform the audio signals into digital pulses, which are then stored on the tape. Both eliminate tape hiss and reproduce sound more accurately than analog recorders. Digital tape recording devices are also used to store programs and data for a computer. Magnetic tape can also be used to store video information. Videocassette recorders use a rotating-head system to increase tape capacity. The recording heads move in a direction almost perpendicular to the tape movement, resulting in diagonal bands of information across the tape width. Over the years a wide variety of tape formats, for both reel-to-reel and cassette recorders have been developed. In most cases tape recording has been superseded by digital recording to solid-state storage or magnetic hard drives. See sound recording ; television .

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

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