Thanks for making me think about that statement.
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So I just watched the two videos that bill_k referenced, and I don't perceive any conflict between what Peter says and what I wrote, except for the fact I was technically incorrect to have written that the AS force is constant. Upon further thought, I see now that, at least for the conventional string and weight type of AS devices, the force pulling the tonearm would increase as the tonearm approaches the label, because the angle between the string and the arm wand is approaching 90 degrees, at which point all of the mass of the weight (force, F) would be pulling on the arm wand in the desired direction.
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FWIW, I wasn’t notified of your response.
The gist of my response to PL is that yes, AS devices might increase the AS force as the stylus approaches innermost grooves, but no, in general AS devices don’t follow the skating force in magnitude. Or AS does not successfully cancel the skating force, to put it another way. I don’t think PL would make that claim.
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bill_k, Can you direct me to Peter Ledermann’s quote as follows: "With all due respect you [referring to me, Lew] stated that "AS is constant in magnitude" which is not true. As Peter Ledermann confirms: "A properly designed anti-skating is non-linear, as it should of course increase A-S automatically as the cartridge approaches the inner grooves."
This stimulated me in several directions. First, it may have been flippant of me to say that AS is constant in magnitude across the LP surface; I should have thought about it in greater detail, but if you consider an old-fashioned string and weight AS device, what would change the magnitude of AS force as the tonearm swings in toward the platter is the angle of the pull of the string/weight on the arm wand, assuming that friction of the string on the guide is unchanging. That changing angle would indeed probably change the magnitude of AS, but such a change would be linear with a slope related to the changing angle of the pull force. That still does not mimic the ups and downs of the skating force. The AS force exerted by a magnetic device would also vary but also would not closely mimic the changes in skating force that occur in the course of playing an LP using a pivoted overhung tonearm. Finally, I wish I knew what tonearm Peter was thinking of when he wrote that passage. Finally, finally, is it indeed true that the max skating force occurs at the innermost grooves? Gotta think more about that one, but off the top of my head, the skating force would be related to the headshell offset angle at the innermost null point (a minimum) and then rise as the stylus approaches the runout grooves. Before the tonearm reaches the innermost null point, the skating force is created by headshell offset angle PLUS TAE. At the outer null point, it is again caused only by headshell offset. And at the outer grooves, again we have both TAE and offset. There is just no way to design an AS device to follow those variations, and this does not even take into account groove tortuosity as another ever changing source of a skating force.
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I don't think it follows from "there is no right setting" that you may as well not use AS at all. And I apologize for coming on perhaps too strongly. I use AS on my overhung tonearms, of course, and I try for a minimum amount that eliminates distortion in the R channel that I can hear with zero AS. So maybe by shooting for that entirely subjective endpoint I end up using a tiny bit more AS with those exotic stylus shapes you mention. I would need the Wallyskater to determine that.
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Mijo, I don't know whether you agree with me or not, but what I wrote is that AS can be exactly equal in magnitude (and hopefully opposite in direction) to the skating force at only two points on the LP surface. It seems to me this is true for any stylus shape, and length tonearm, etc. Because AS is constant in magnitude and direction while the skating force describes a kind of eccentric parabola if you plot its magnitude with respect to the distance between the innermost and outermost grooves, and this is disregarding the vicissitudes of the skating force that are due to the program material. A straight line (the graph for AS) will intersect the skating force parabola at two points, unless AS is incorrectly set lower than the skating force minimum or higher than the skating force maximum. And anyway, do you REALLY think there is much difference between 9, 10, 11, or 12% of the skating force?
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At best, any AS setting can be correct (exactly equal in magnitude to the skating force) at only two points on the LP surface. There is a fairly broad range of settings that will satisfy that requirement, 11% of VTF being one of them. I’d be curious to borrow a Wally just to find out how close I get to 11% by simply setting AS to a minimal value above zero .
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Why must I have the Wallyskater, if I have both a Smartractor and a Feickert protractor? To set AS? Or what?
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I agree with all you say above, but I just wanted to point out that increasing (what I thought was EL but my in fact be P2S) from 222mm to 225mm has little effect on effective mass, which of course has nothing to do with alignment per se. If we are actually talking about P2S, then the net effect on effective mass of the commensurate increase in EL would be even less than 2%. But for EL, if effective mass was 20g at 222mm, it would be ~20.4g at 225mm. (This is very inexact, just comparing the square of the two numbers, which is directly proportional to effective mass.)
Looking back on my nearly 50 years in this hobby, I would unashamedly say that there are some things I did wrong for 40 of those years, some other things that I did wrong for 30 years, and some more unknown things that I am doing wrong even now. (Not speaking only of tonearm alignment.) For the uninitiated or newbies, they should know it's a marathon, not a sprint to get to audio Nirvana. But such is our capacity for self delusion that one can enjoy the hobby from the get-go, just keep an open mind and hope to get better at it.
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Dover, I’m not quite sure what the argument is really about but my calculations suggest that a change in EL from 222mm to 225mm would increase effective mass by only about 2%.
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I am struggling with ..."any given frequency has a shorter wavelength as the groove speed declines,...." That is from Mijo's post but he was only reiterating a quote from Raul. Frequency and wave length are inversely and constantly related, regardless of groove speed. For example, a 1000Hz tone always has a wave length in air of 0.32 meters. And the declining groove speed on an LP, as the stylus approaches the label, is presumably accounted for in the recording process. I am sure the text is trying to tell us something, but what? I think it's semantics. I think it means there is less groove length per second available to encode a given frequency to the point where the stylus has difficulty tracing the groove accurately. And this does not even take into account TAE.
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This is why I am an alignment nihilist and now very fond of an underhung tonearm that has no headshell offset angle (or significant skating force) to worry about. All that’s left to worry about is zenith error. Even a 1 or 2 degree error in zenith, if ignored, will cause problems with alignment, no matter how otherwise precise.
Mijo, you are probably correct about image focus, but when you do twist the cartridge in the headshell, then you are putting unequal forces on the cantilever (up and down motion of the cantilever is not in line with up and down motion of the headshell and bearings at the pivot). I don’t know what that does sonically, but it may do something we hear.
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Mac, I think you’re referring to adjusting the cartridge (not the tonearm) for zenith error, which is worth doing but has nothing to do with setting overhang. OTOH, Wally can probably advise on how to alter headshell offset and P2S, if you’re using a non-spec overhang.
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I don’t think I explained it so much as I was trying to point out that if you change recommendation for overhang, you have to change other parameters like headshell offset and P2S, if you want your two null points to lie anywhere in the playing surface of an LP. That’s not a trivial exercise. Hearing it is another matter entirely.
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Whether you can hear a difference or not, even an 0.5mm error or greater in overhang, provided you don’t also alter other standard parameters, certainly CAN make a drastic difference in locating the two null points, or even whether you actually get two null points anywhere on the playing surface of an LP. This has been demonstrated, probably by Dave Slagle, but I can’t find the reference.
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