Ok I have a theory...
On a conventional arm with offset headshell..if you draw an imaginary line extending the cantilever, past its suspension point, all the way backwards to the plane of the arms pivot point. Viewed from the front of the cartridge, the new ultra-long cantilever will terminate at a point way above and to the right of the arms pivot point.
Now the theory...Attached here is a link that very graphically shows the magnitude of stylus drag. ( I hope the link works) watch to at least 4 mins.
Скатывающая сила как измерить (youtube.com)
Now pull on the stylus ... due to the compliance of the cartridge suspension AND the headshell offset, the end of our extended cantilever will move downwards and to the left. If there was enough travel in the cartridges suspension and if we pulled on the stylus hard enough, the extended cantilever would ultimately touch the arms pivot point.
So back to an actual cartridge... the action of stylus drag causes the cantilever to squat down a little. This has been talked about in other forums, and I believe mentioned by Michael Fremer, but the action of stylus drag with an offset headshell also causes the cantilever to move to the right when viewed from the front of the cartridge. By how much? I don't know... would it be enough to cancel a carefully set up Lofgren alignment? Possibly. Would it cause an increase tracking error distortion? Maybe.
Would it mean that a underhung arm, when playing a record actually has less tracking error distortion than an offset overhung arm? IOW opposite to what the theoretical static calculations would suggest. ..Maybe.
If this 'yawing' action is a thing, it would be constantly changing with the level of modulation. I could speculate that it would result in a kind of "dirtiness" to the sound and a sense of the stylus scratching its way thru the groove.
Cheers.
