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Pinch Wheel
Pinch wheel or pinch roller is the term for the "rubber" wheel which forms part of the drive mechanism in many forms of tape recorder and player. The magnetic tape is squeezed between the "capstan" (a precision shaft driven at constant speed) and the pinch wheel and so is drawn past whatever combination of record, replay and erase heads the "tape deck" employs. The pliability, surface, and other physical characteristics of the "rubber" material from which the pinch wheel is made is critical to the steady progress of the tape, and usually degrades with time, and may result in speed fluctuations, causing "wow (recording), wow and flutter", various noises and even damage to the tape. Pressure of pinch wheel against the capstan is usually removed when not in operation, to reduce incidence of "flat spots" on the rubber surface. Replacement of pinch wheels is a common maintenance problem. A similar situation applies to some record players, where a pinch wheel is the intermediary between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Tape
Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic tape could with relative ease record and playback audio, visual, and binary computer data. Magnetic tape revolutionized sound recording and reproduction and broadcasting. It allowed radio, which had always been broadcast live, to be recorded for later or repeated airing. Since the early 1950s, magnetic tape has been used with computers to store large quantities of data and is still used for backup purposes. Magnetic tape begins to degrade after 10–20 years and therefore is not an ideal medium for long-term archival storage. Durability While good for short-term use, magnetic tape is highly prone to disintegration. Depending on the environment, this process may begin after 10–20 years. Over time, magnetic tape made in the 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wow (recording)
Wow is a relatively slow form of flutter (pitch variation) that can affect gramophone records and tape recorders. For both, the collective expression wow and flutter is commonly used. Gramophone records When playing gramophone records, wow is a once-per-revolution pitch variation which could result from warping of the record or from a pressing plate that was not precisely centered. If the grooves are not centered exactly relative to the spindle hole, the linear velocity of the stylus, instead of dropping gradually as the groove spirals towards the center, varies every revolution to be too high (resulting in a higher pitch) when the stylus is further out, and too low when the stylus is further inwards (resulting in a lower pitch). The more eccentric the positioning, the greater the pitch variation. The cause for "wow"-effects on a warped disc is basically the same; a variation in the linear velocity of the stylus relative to the disc. This can be by either radial warping (simila ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
