| Problems with Pivoted Tonearms The fundamental limitations of the pivoted tonearm will explain the reason for the tangential tonearm's existence. Tracking error |
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The ideal tonearm would allow the cartridge to maintain the
same angular relationship with the record groove as the
record-cutting stylus had with that groove. LP cutting lathes
are all linear-tracking; the cutting head moves in a straight
line across the lacquer master. But in a pivoted tonearm, the
cartridge end swings in an arc over the record, causing the
playback stylus to turn slightly in relation to the groove.
The stylus/groove relationship is constantly changing with a
pivoted tonearm. The result is tracking error (diagram 17),
defined as a difference in the stylus/groove relationship
between the cutting stylus and the playback stylus. This
disparity in the paths followed by the cutting stylus and
replay stylus leads to distortion. In order to reduce horizontal tracking error, tonearms have an overhang and an offset angle (diagram 18). The distance from stylus to arm pivot is greater than that from record center to arm pivot (by a distance called the overhang). Note that adding an offset to the tonearm doesn't eliminate tracking error. |
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