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In the Forum: Analog Playback
In the Thread: Copper Mat on a Micro Seiki Gun Metal Platter
Post Subject: The "C" wordsPosted by Wellington on: 10/13/2015
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 Romy the Cat wrote:

Soory, Be, no matter how I look into it I can’t understand why circumference force would make the arm to move inward. If you spin your platter not at 33 but at let say 45 and pule some light subjects on the platter then they will be thrown off the platter. A needle and a tonearm are the subject of the very same forces and this is why LEFT side of the needle worn more if anticaking is not enough. The platter spins clockwise, so the needle left (the external) side pushed by circumference force press harder to the left side of the groove. It is not a surprise that the left side her more distortions and trucking problem when anti-skating is not enough. When you make a left turn at high spin then your car rolls over it’s right side- or outside of your driving trajectory…. Right?

I think that the "C" words, centripetal, centrifugal and circumferential are causing you confusion. If a loose object is placed on a rotating platter so that it too rotates, and the centripetal force requirement is NOT met (which would be a constraint that would pull it toward the spindle. Imagine a string.), then the object will roll off the edge of the platter, because it has momentum and it seeks to travel in a straight line, not in a curve. In order for the tonearm to share the same motion as this object it would have to be rotating around with the platter. But the tonearm only pivots; it doesn't rotate with the platter. The skating force is not about those "C" words. Skating is simply caused by the friction of the groove walls passing by the stylus at an offset angle. Uncompensated skating force increases groove wall forces on the inner groove which is the left-channel side. The outer side, the right channel, sees a reduced force. If tracking force is high enough the stylus will stay in contact on both sides most of the time and distortion might be acceptable. In that case you'd expect more wear on the inner stylus surface. But if the tracking force is too low to overcome the skating force's reducing the force on the outer groove wall, the stylus will mistrack frequently on the outer right-channel wall with the stylus leaving the groove surface and then slamming back again. In this case the outer groove wall and the outer stylus edge will wear prematurely.

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