Stanwal, first of all the Grace 707 is a vintage tonearm calibrated for MM cartridges, not MC which require far less AS. The rule of thumb in the MM days was that the AS should equal the VTF, and even at that, how much sideways AS force (in grams) was applied was definitely NOT the same as the actual weight on the string. Skating force is expressed as torque (foot-pounds, or centimeter-grams in the case of tonearms) and is the product of friction (in grams of drag) TIMES the (virtual) lever arm created by the tonearm offset, in centimeters; and is easily calculated if you know the amount of drag of the stylus in the groove (admittedly hard to determine without proper instruments ;-) The lever arm length is a result of the tonearm dimensions and offset angle. Those two factors don't change, regardless of where the tonearm is positioned. To be fair, the amount of groove friction actually CAN change (but only very slightly) between the beginning and end of the record as a result of the slignt difference in linear velocity (the speed of the groove under the stylus) between the outside and inside grooves of the record -- not enough to make a significant difference in AS force required. I suppose if one wanted to get REALLY nit-picky, one could also mention that louder passages produce more friction than softer passages. But that's pretty much it in terms of the causes of skating force (torque.).
With all cartridges except those with the stiffest suspensions, as long as you can see the cantilever from the front of the cartridge, it's quite easy to set AS force visually. I always did it that way with my MM Shure cartridges. You just lower the stylus into the groove while watching the cantilever from the front. If it deflects to the right (relative to the cartridge body) you need to add AS force. If it deflects to the left, AS needs to be reduced. No deflection of the cantilever when the stylus hits the groove means the skating force is balanced out. It could also mean that the skating force (even without AS applied) is not enough to alter the relationships in the cartridge's generator (usually because the suspension is stiff enough to resist the skating forces) and so you would HEAR no difference with or without AS applied. Nevertheless, with no AS applied, the inner groove wall of the record would wear faster than the outer groove wall ;-)
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With all cartridges except those with the stiffest suspensions, as long as you can see the cantilever from the front of the cartridge, it's quite easy to set AS force visually. I always did it that way with my MM Shure cartridges. You just lower the stylus into the groove while watching the cantilever from the front. If it deflects to the right (relative to the cartridge body) you need to add AS force. If it deflects to the left, AS needs to be reduced. No deflection of the cantilever when the stylus hits the groove means the skating force is balanced out. It could also mean that the skating force (even without AS applied) is not enough to alter the relationships in the cartridge's generator (usually because the suspension is stiff enough to resist the skating forces) and so you would HEAR no difference with or without AS applied. Nevertheless, with no AS applied, the inner groove wall of the record would wear faster than the outer groove wall ;-)
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