Audio-Technica AT-20 (Years Unknown)
Little is documented about the Audio-Technica AT-20. We can't even confirm what kind of product it was. The "AT-20" designation could refer to a phono cartridge, microphone, or other Audio-Technica product, and no source in our archive explicitly names the plain "AT-20" model and describes it. We are not going to invent a spec sheet to fill the gap.
What the record does show is a close relative: the AT-20SLa, which appears in a period survey of CD-4 quadradisc pickups. Audio (March 1974, p.44) measured that cartridge and reported it as one of the two top CD-4 cartridges tested. The reviewer called its trackability among the best he had seen and noted its sonic clarity. The measured figures for the AT-20SLa were a weight of 9.03 g, a DC resistance of 550 ohms, 378 mH inductance, 0.65 mV/cm/sec output, and crosstalk of -22 dB. If the AT-20 is the base version of that design, those numbers may be a reasonable guide to the family. But they belong to the SLa, not to a confirmed AT-20.
A separate Audio-Collection compliance chart lists the AT-20SLA in the high-compliance bracket, which is consistent with the Shibata-equipped CD-4 role. Beyond that, the AT-20 itself has no confirmed production years, no confirmed original price, and no confirmed body or stylus specification in any source we hold. A photograph of the stylus and the markings on the body would help close the gap.
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