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phonograph,device for reproducing sound that has been recorded as a spiral, undulating groove on a disk. This disk is known as a phonograph record, or simply a record (see sound recordingsound recording,
process of converting the acoustic energy of sound into some form in which it can be permanently stored and reproduced at any time.
In 1855 the inventor Leon Scott constructed a device called a phonautograph that recorded tracings of the vibrations of
..... Click the link for more information. ). In using a record player, a record is placed on the player's motor-driven turntable, which rotates the record at a constant speed. A tone arm, containing a pickup at one end, is placed on the record. The tone arm touches the groove of the record with its stylus, or needle. As the record revolves, the variations in its groove cause the stylus to vibrate. The stylus is part of the pickup, a device that also contains a transducertransducer,
device that accepts an input of energy in one form and produces an output of energy in some other form, with a known, fixed relationship between the input and output. One widely used class of transducers consists of devices that produce an electric output signal, e.g.
..... Click the link for more information. to convert these mechanical vibrations into corresponding electrical signals. These signals are then increased in size by an amplifieramplifier,
device that accepts a varying input signal and produces an output signal that varies in the same way as the input but has a larger amplitude. The input signal may be a current, a voltage, a mechanical motion, or any other signal; the output signal is usually of the
..... Click the link for more information. . After leaving the amplifier, they are passed to a loudspeakerloudspeaker
device used to convert electrical energy into sound. It consists essentially of a thin flexible sheet called a diaphragm that is made to vibrate by an electric signal from an amplifier.
..... Click the link for more information. that converts them into sound.
Although sound waves had been recorded in the middle of the 19th cent., the first machine to reproduce recorded sound, the phonograph, was built by Thomas A. Edison in 1877. Edison's records were made of tinfoil, upon which a groove of unvarying lateral direction but varying depth was cut; later this method became known as "hill-and-dale" recording. In 1887, Emile Berliner invented the disk record (patented 1896), which has grooves of unvarying depth but of varying lateral direction. His method, called lateral recording, superseded the earlier method. Berliner also invented the matrix record, from which unlimited duplicate recordings could be pressed. Early turntables were operated by a spring-driven motor that required rewinding for each record played; later the use of an electric motor made rewinding unnecessary.
The quality of reproduction was greatly improved by high-fidelity amplification (popularly called hi-fi) and by complex speaker systems. From 1948 records were made to be played at slower speeds, thus lengthening the amount of material that could be recorded on a single disk; such long-playing discs were known as LPs. Stereophonic reproduction was achieved by adapting the phonograph to reproduce two channels of sound (see stereophonic soundstereophonic sound,
sound recorded simultaneously through two or more electronic channels. For live recordings, microphones are placed in different positions relative to the sound source.
..... Click the link for more information. ). The first commercially available stereo recordings were produced in 1957. In addition to musical performances, records were often used to reproduce sound effects for radio and the theater, transcriptions of radio broadcasts, "talking books" for the blind, and lessons for language study. Most recording companies stopped producing phonograph records by the early 1990s in favor of cassette tapes and compact discscompact disc
(CD), a small plastic disc used for the storage of digital data. As originally developed for audio systems, the sound signal is sampled at a rate of 44,100 times a second, then each sample is measured and digitally encoded on the 4 3-4 in (12 cm) disc as a series of
..... Click the link for more information. .
See B. Steffens, Phonograph: Sound on Disk (1992); E. L. Reiss, The Complete Talking Machine: A Collector's Guide to Antique Phonographs (1998); T. C. Fabrizio and G. F. Paul, Antique Phonographs: Gadgets, Gizmos, & Gimmicks (1999).
an electromechanical device in the equipment for the reproduction of sound from recordings. A record player is a component of phonographs, radio-phonographs, and other household and professional sound-engineering systems.
The main elements of a record player are a turntable and a sound pickup, which consists of a cartridge and a tone arm. The turntable rotates the phonograph record; the sound pickup converts the mechanical vibrations of a needle into electric oscillations (see alsoSOUND RECORDING, MECHANICAL). In addition, a record player often includes an audio-frequency preamplifier, which corrects frequency distortion.
A record player provides for one or more speeds of rotation, or turntable speeds. The most widely used turntable speed is 33 1/3 rpm; others in use are 78, 45, and 16 2/3 rpm. Depending on its purpose and rating, a record player maintains, within prescribed limits, the values of the parameters that characterize the quality of the reproduced sound. Such parameters include the stability of the turntable speed, the permissible distortion of the electric signal shape, and the acoustic and electrical noise levels.
REFERENCESApollonova, L. P., and N. D. Shumova. Mekhanicheskaia zvukozapis’. Moscow-Leningrad, 1964.
GOST 18631–73: Ustroistva elektroproigryvaiushchie: Osnovnye parametry, tekhnicheskie trebovaniia.
S. L. MISHENKOV