The 7-inch 45 rpm record was introduced in 1949 by RCA as a smaller, more durable and higher-fidelity replacement for the 78 rpm shellac discs.
Singles have been issued in various formats, including 7-inch, 10-inch and 12-inch vinyl discs. The most common form of the vinyl single is the 45 or 7-inch, the names are derived from its play speed, 45 rpm and the standard diameter 7-inch.
The 7-inch 45 rpm record was introduced in 1949 by RCA as a smaller, more durable and higher-fidelity replacement for the 78 rpm shellac discs. The first 45 rpm records were monaural, with recordings on both sides of the disc. As stereo recordings became popular in the 1960s, almost all 45 rpm records were produced in stereo by the early 1970s.
The most common form of the vinyl single is the 45.
Although 7 inches remained the standard size for vinyl singles, 12-inch singles were introduced for use by DJs in discos in the 1970s. The longer playing time of these singles allowed the inclusion of extended dance mixes of tracks. In addition, the larger surface area of the 12-inch discs allowed for wider grooves (larger amplitude) and greater separation between grooves, the latter of which results in less cross-talk. Consequently, they “wore” better, and were less susceptible to scratches. The 12-inch single is still considered a standard format for dance music, though its popularity has declined in recent years.
Depending on its type, in addition to the song itself, a single may include remixes of the song, additional songs, a music video for promoting the single, and a collectible poster.
Modern stereophonic technology was invented in the 1930s by British engineer Alan Blumlein at EMI, who patented stereo records, stereo films, and also surround sound.
Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of directionality and audible perspective. This is usually achieved by using two or more independent audio channels through a configuration of two or more loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing. Thus the term “stereophonic” applies to so-called “quadraphonic” and “surround-sound” systems as well as the more common two-channel, two-speaker systems. It is often contrasted with monophonic, or “mono” sound, where audio is in the form of one channel, often centered in the sound field. Stereo sound is now common in entertainment systems such as broadcast radio and TV, recorded music and the cinema.
How It Works
Stereo sound systems can be divided into two forms: The first is “true” or “natural” stereo in which a live sound is captured, with any natural reverberation or ambience present, by an array of microphones. The signal is then reproduced over multiple loudspeakers to recreate, as closely as possible, the live sound.
Secondly “artificial” or “pan-pot” stereo, in which a single-channel (mono) sound is reproduced over multiple loudspeakers. By varying the relative amplitude of the signal sent to each speaker an artificial direction can be suggested. The control which is used to vary this relative amplitude of the signal is known as a “pan-pot”. By combining multiple “pan-potted” mono signals together, a complete, yet entirely artificial, sound field can be created.
Stereophonic sound attempts to create an illusion of location for various sound sources within the original recording.
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