Flieb, Thanks for saying exactly the same thing that I said in fewer words and without the physics lesson. If my point(s) were moot, your points are moot-er. I realize that an experienced person such as yourself would have the facts well in hand. My post of 4-13 was aimed only at those who might not.
The RS-A1, and any other tonearm designed for "underhang" and lacking any headshell offset, WILL achieve zero skating force at the one (not two) points across the LP surface where it also achieves tangency. (Because the stylus underhangs the pivot, there can only be one point on the arc where tangency to the groove is achieved. However, at that one point, there is no headshell offset to generate skating force.) I know you know this, Fleib.
Why is there no skating force on a linear tracker? The whole idea, as you know, is that there is ALWAYS tangency to the groove, and there is never headshell offset angle. Thus, no skating force. However, in practice, if there is even a minute error in set-up; if the stylus is not exactly on the imaginary line that describes the radius of the LP, then there will always be that tiny amount of skating force. Also, if there is any play in the bearing such that the stylus can describe even microscopic arcs as it travels across the LP, this too will generate a small skating force. The Rabco/Goldmund linear tracker actually depended on its loose bearing to periodically activate a servo motor that dragged the assembly across the LP. That was not a good design, IMO. I know you know this, Fleib.
