My memory is that when tonearm manufacturers began adding antiskate to their tonearms, in the form of springs or strings with weights, their instructions always said to set the antiskate (force) to match the VTF. The reason I put "force" in parentheses is because it was never clear to me, and still isn't, that those AS scales on tonearm dials/weights refer to an actual measurement of sideways force, or whether they're just arbitrary numbers.
Anyway, when the cartridge had a high enough compliance to actually see the deflection, there was no problem just doing it visually, it was so obvious, and that was that. I never ran across the 1/3 figure until I read A.J. van den Hul's very informative and extensive phono faq page -- updated in 2003:
http://www.vandenhul.com/artpap/phono_faq.htm
Tracking at the lowest possible VTF is also something that belongs to the MM/elliptical stylus era. I'm not sure why, but perhaps it had to do with the extremely high compliance of those cartridges and the ultra lightweight tonearms of the time. A typical Shure cartridge tracked at .75-1.5 gm, and the cool thing was to get them to track at .5 gm, especially if you had a great lightweight tonearm like the old Infinity Black Widow!
While times and designs change, physics remains constant. Today's MC cartridges have lower compliance, higher tracking force and micro-ridge styli. And everyone now seems to have discovered that they track better at the high end of their VTF range rather than the low end. That, along with careful SRA adjustment, results in less groove wear, counterintuitive as that may seem to some. But the more extensive use of MC cartridges now, is IMO what has made antiskating adjustment a more important issue than it used to be.
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