A quintessential high end rig back in the 70s was a Rabco SL8E mounted on a Thorens TD125. Then came the ginormous Goldmund Reference TT with their version of the Rabco, all in black. Very sexy. But I agree with Mijo.
Has This Kind of Tonearm Been Made?
I was looking at my son’s 3D printers and observing the gantry that carries the print head. Microprocessor controlled, very precisely, with a stepper motor and a toothed belt. A wire loom made like a bicycle chain curls up to hold wiring out of the way as the head moves back and forth.
So I started to think: what if such a gantry was mounted across the centre of a turntable? It could be hinged where it attached to the far side of the turntable, and on the playing side it could be located by dowel pins in holes as it is lowered. A catch could click into place and hold it at precisely the right height over the turntable. The cartridge can be mounted to the traveller on the underside of the gantry, such that its stylus is exactly over a line passing through the record spindle, and it will be at a perfect tangent all across the record, and without the play associated with the stubby tonearm of a linear tracker. How to adjust VTF? I suppose the two cartridge screws could be made such that by twisting both, the cartridge lowers or rises, placing more or less pressure on the cantilever (and a gauge can sit in place of the disk to set this). Twisting only one of those screws could adjust azimuth. Or in a more expensive version a strain gauge could be incorporated and allow adjustment to be quantified that way. I expect an Arduino could be programmed to control the movement across the record at the correct rate for outer to inner grooves.
To play you lift the gantry, hinging it upwards to a near vertical position. A cam and sprung follower can easily hold it elevated. A record is placed on the table and rotation started. The gantry is lowered and it clicks into place as the stylus rests on the disk. At the end of the side either the turntable motor is switched off by the microprocessor controlling motion of the cartridge carriage, or the catch holding the gantry down can release allowing the gantry to spring up slightly, just enough to lift the stylus off the record. Perhaps instead of a mechanical catch it could be electromagnetic and the current is cut as the stylus enters the deadwax, again allowing the gantry to lift a little.
I imagine someone has thought of this before, but I haven’t seen one. Has it been done, or shall we patent it?!