The design requirements of a pickup and arm suitable for use in quality control of records are presented. It is shown that for accurate tracing of records the dynamic mass of the cantilever must be 1 mg or less, and the compliance must not be less than 4 x 10/-6 cm/dyne for a playing weight of 2.5 g. Damping of the arm is necessary if the pickup is to remain in contact with the groove walls under adverse conditions. The pcikup has a wide frequency response, good channel separation and ability to reproduce faithfully the recorded waveform. Wear of both stylus and record is considerably reduced due to the small dynamic mass of the cantilever and by complete control of unwanted resonances.
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