Anti-skate

Larri, you have progessively smaller circles as you get closer to the end of the record. The speed is constant. You have a fixed pivot(bearings)far away. If you think about it, the force generated inward towards the spindle would be greater as you get to the inner part of the record. These really aren't circles, otherwise the same passage would repeat. They lead towards the spindle. So you have this big circle(per se) on the outer part of the record. There is not a great inward pull here. You have this small circle on the inner part of the record. These aren't circles-they all lead to the spindle. The pull inward towards the spindle is much greater with the small circles. I believe if you think about it, the differences in the inward pulling would be obvious. This isn't a scientific explanation, because maybe what you are counteracting with anti-skate is the acceleration of the inward pulling. I believe VPI uses a uni-pivot arm, which might use a knife edge instead of one set of bearings(which also means it doesn't have the top bearing). This combination(with maybe a little viscous damping)might negate the need for anti-skate. I could be wrong, but isn't the Graham arm also uni-pivot?

Ghost_rider, I looked up your Sumiko Black Pearl, and Sumiko's recommendation on that cartridge is to use the same amount of anti-skate as the tracking force(recommended tracking force is 2 grams, and the range is 1.5 to 2 grams). I assume your dealer did this. If you want to fine-tune the anti-skate, I suggest you ask yourself if records sound better maybe on the last 3 songs than on the first 2. By better, I don't mean that the bass sounds better, or any of that audiophile b.s.. What I mean is, do you enjoy those tracks more, or do you have more of a sense of ease on those tracks. If that is the case, then you have too much anti-skate(by too much, I mean a tiny, tiny bit). Just barely lower the anti-skate, then listen. Does it make the whole record sound better to you? If so, you have improved the anti-skate setting. What you are doing is actually balancing the channels, I believe. I would experiment like this, until you can hear the differences that changing anti-skate make-then you will know how to fine-tune anti-skate.

Mmakshak,

The skating force has nothing to do with the diameter of the record. It has to do with the fact that the drag of the stylus in the groove is pulling backwards along a line tangent to the groove (along the same line as the cantilever), but that is not the same line as from the stylus to the pivot because of the offset angle of the cartridge. If you did a vector analysis, you would see that there is a vector component that is inward. If there is somehow greater drag toward the inner groove, then yes, there should also be a bigger vector component of antiskating. I just don't see a reason to expect appreciably greater drag at the inner grooves.

Greater distortion in the inner groove is most likely the product of the physical compression of the waveform, described by the groove, into a smaller space. This is why some early proposals for records had the stylus playing from the inside out. Because music typically has its peak volume (climax) at the end of the piece, it made sense to put those wide swinging grooves at the outside diameter where they would not be so compressed into a smaller space.

Darn Larryi,your a pretty smart guy!! -:)

Assuming correct alignment, inner groove distortion is generally the result of:

1. Resonance and improper tonearm damping.

2. Reduced groove velocity at the inner grooves. On a record the average outer groove starts at 11.5 inches diameter and the inner groove at 5.8 diameter. So, the inner groove is 50.4 percent the linear velocity of the outer groove. Put another way, if someone handed you a record that ran at 16.8rpm you wouldn't you expect the outer groove to sound great. That's the effective velocity of the inner groove if it were to run at the outer part of a record spinning at 16.8 rpm.