OK.... being young enough to never have owned vinyl, wtf IS that?

Why that, my young lectric, is a tone arm.

All turntables have tone arms, I think, but most of them pivot from a fixed point. Not a big deal in the mono era, but, or so the wisdom went, when stereo LPs came onto the market the changing angle of the stereo stylus -- in relation to the stereo grooves -- could lead to an unhappy reduction in stereo separation on parts of the record.

Enter the Rabco SL8, then SL8E. The idea was to maintain perfect alignment with the groove -- they were referred to, I think, as Rabco tangential tone arms. The tone arm rides in a counterbalanced carriage on rails with jewel bearings. As the record grooves pull the stylus inexhorably to the middle of the LP, the tone arm begins to angle inward away from the tangent. When this happens, it closes an itty-bitty wire contact that powers a little motor that moves the carriage (the ass end of the tone arm) along the rails until the tone arm is back in tangent, the contacts reopen, the motor shuts off....repeat as necessary until LP is finished.

OK, I don't *really* think it was the Empeg of its day -- how could it compare -- but it was pretty neat. They integrated a simplified version of this into a Harmon Kardon turntable, but IIRC it relied on cruder, friction devices to move the arm. The SL8E was the pinnacle of wierd tone arm technology.