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The Westrex 2B is a motional feedback cutter head, introduced in 1952 by the Western Electric Export Company. It followed hot on the heels of the Westrex 2A, dating from 1947, which was itself a lateral implementation of the principles first described by Wiebusch, Vieth and Yenzer in 1938, with a couple of relevant patents issued by 1939, for a vertical cutter head employing motional feedback.

A customer recently imported a vintage Presto 75A disk recording lathe from the USA, with a view to cutting records in Europe.

He quickly discovered, like many people before him, that it was spinning a bit slower than it should, when operated from 50 Hz mains, via a simple step-down transformer. As with most vintage record cutting machines, the platter is powered by a synchronous AC motor, which "locks" to the line frequency.