Anti skate and tonearm damping query

Thanks for that Tom............

Dertonarm has stated the facts as I have always heard them. If it was that easy to apply the correct force then why, for example. did the Grace 707 bias control give twice the necessary force? It was a well designed arm. I have never heard that a given amount of bias compensation would be correct all across the record, the setting is always a compromise. That said, the compromise I chose is not to use any.

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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Nsgarch explanations are based on the original patent description of skating force and the anti-skating applied. And its too is not a matter of MM-cartridges vs MC-cartridges. Their different basic mechanical characters do contribute some details to the behavior, but not essentially so.
This general patent description from over 60 years back - while not entirely incorrect - is an incomplete model and is simplifying a quite complex issue. All anti-skating devices designed for tonearms are based on this patent description and a simplified model which gives the impression that skating is a constant force which can be nulled with a correct applied counterforce.
Well - it is a neither constant nor linear force and it is depending on tonearm length (with the resulting offset being more or less depending on effective length), stylus shape, size (especially so by older elliptical/conical styli, which do create a "double-side-contact" towards the inner grooves! )and alignment, groove cut, VTF, groove-compliant VTA and tonearm geometry aligned for (2nd zero close to inner grooves give another benefit here... see our sadly deleted tonearm geometry thread from early summer...... if you saved it in time).
As I said before - this is NOT a simple model.
I still believe that it is rather smart not trying to counter a highly variable force with a constant applied anti-force. It is obvious, that there are only very few seconds of the 20-35 minutes of a record side in which the counter-force is really correct and nulling the skating force of the moment. During the rest of the time the anti-skating applies a more or less unwanted side force of its own - just going in the opposite direction.
With the standard "skating vs. anti-skating"- model we have a model which is incomplete and the consequences drawn from it were wrong.
We would need a variable anti-skating force based on the tangential curve of the given tonearm. This antiskating force would then be inverse to the tangential curve and would indeed null the skating force if properly aligned.
Several questions in tonearm geometry today are long set aside as "complete", but are based on models which were simplified and as a result of this simplification did not give the correct results.
But so far we are living with these - less than optimal - results.
Partly due to laziness, lack of knowledge, partly ignorance (this is not meant to offend anyone !!), partly ease of use.

Dertonarm, my explanations are based on the Laws of Mechanics introduced by Sir Isaac Newton July 5, 1687, and which remain true and in use to this day. You can point to all the little nuances which you assert would have an effect on the basic design, but they are so small as to be irrelevant. You seem to want to make things as complex as possible, which makes any useful solution impossible of course. Nonsense!

As I said before, I have no problem with your expressing your ideas, but remember, without any scientific proof or technical underpinnings, that's all they are: thoughts, and whimsy ;-)

Anti skating in it's basic form is a very useful concept, if only to prevent uneven record wear and reduce surface noise in the left channel. To those who think anti-skating is of no value, or just TOO COMPLICATED to implement (dear, dear!), I say, "don't worry, be happy" or better yet, get a 16" tonearm with no offset ;-)