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Thursday, June 3, 2010

Radio Killer - Be Free (Deepside Deejays Remix)

Turntable History

"In reproducing a phonograph record, the aim is to take out of the groove exactly the intelligence that was pressed into them. And the wiggles in the groove are meaningless in themselves. They have to induce exactly the right physical motion in a stylus before they make sense---which means that they must move under the stylus at the right speed and that the stylus itself must track the groove accurately, wigwagging as the wiggles demand. A turntable spins the grooves; a tone arm holds pickup and stylus in place. What we want from the turntable sounds simple, but it isn't. In the first place, there are three speeds: 78.26 rpm for the old-fashioned standard shellac records, 45 rpm for the little seven-inchers with the big center holes, and 331/3 rpm for long-playing discs. The speed must be exact in every case. If the turntable is slow, the pitch drops; if fast, the pitch rises.
Moreover, the speed must be exact at every instant of playing. A turntable that alternately slows down and speeds up will ruin musical enjoyment even though its average in each rotation is an exact 78.26, 45 or 33 1/3 rpm. The phenomenon produced is called "wow," a very expressive word denoting the alternating rise and fall of musical pitch which results from fluctuations in turntable speed. When these fluctuations are rapid, the term is "flutter."
The ordinary shaded-pole motor, which runs your electric drill or power saw, is no good for such precision work because any variation in the voltage of your house current will change its speed. Most turntables use a specially designed "induction" motor which is fairly stable in feed, though extreme changes in line voltage may disturb it (look for a tag stating its requirements: "95-130 volts" means disaster-proof). Even this isn't absolutely steady. The 60-cycle alternation of AC electric supply, however, is invariable (an electric clock practically never goes wrong), and thus a "synchronous" motor, which decides its speed by the frequency of alternating current, can keep a constant rpm unless a complete power failure occurs. It also eliminated the dangers of turntable rumble and extruded "hum." Getting this constant speed of the motor up to the turntable (in three different varieties) takes considerable ingenuity. Today's best and most expensive turntables use one of five methods to translate motor speed into turntable rotation.
A turntable does not become a record player until you add a tone arm, which must be separately purchased and mounted. Like the custom turntable, the separate tone arm solves a multitude of problems. You will recall that the cutting stylus rides across the record on a bar from circumference to spindle, following a true radial path always at right angles to the line of motion of the groove. For accurate reproduction, the playback cartridge, too, should always point straight down the groove, so to speak. But we bold the playback stylus in a tone arm, which pivots, making a curved rather than a straight track across the record. In a really bad tone arm, the playback stylus will sometimes be off as much as 10 or 15 degrees. The message of the wiggles is distorted, and the record wears unevenly and more quickly, as does the stylus itself. This is known as "tracking error." " Full article available at
Magazin oficial Catalin Botezatu

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