Apologies to all but apart from being difficult to see, the first part at least sounds like cobblers. The Wikipedia page is pretty vague as well. The low frequencies are NOT attenuated to "prevent the needle jumping out the groove" :cressy wrote:being having a good read of this
http://www.platenspeler.com/background/ ... und_1.html
"The RIAA (Record Industry Association of America) characteristic, which is [also] embodied in British Standard 1928:1955, specifies that a record groove is cut [initially] with constant amplitude modulation, from 20 Hz to 500 Hz. Played back by a magnetic pick-up cartridge, the output signal voltage amplitude then rises at the rate of 6dB per octave, or 20dB per decade. After 500 Hz it is cut at constant velocity - [for which the cartridge output voltage is constant at all frequencies above 500 Hz. This is the original EMI standard. The superceding Decca standard is the same, but with the addition of] - "treble pre-emphasis, which comes in at about 2123 Hz. The net result is a replay curve with an average rise of just below 6dB/octave over the entire spectrum, with a small 'step' at the middle frequencies."
- Gordon J. King, Audio Equipment Tests
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