If the major axis of an elliptical stylus is not in perfect line with the disc radius, one side will be slightly ahead of the other in the groove. Spurious phase differences between channels will thus result, degrading the stereo image. These are not produced by a spherical stylus. Skew is caused by incorrect mounting of the stylus on its cantilever (manufacturing tolerance is +3 degrees), an off-centre cantilever. and lateral tracking error.
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