High speed dubbing uses a master tape that runs at any speed form x32 to
x100 and a slave that runs at the same multiple. A friend of mine still
has his operation going although he has switched to a digital bin loop.
I visited him two weeks ago and he had me listen to one of the cassette
made on the digital system (played back on a Nak cr-7. I sounded
wonderful, not like the crap we bought when we were young.