Yep. It's a parabola of sorts. And if AS is virtually constant, it can be represented as a straight horizontal line on a graph of distance across the LP surface vs force (AS vs Skating on the same graph). So you can visualize that a straight line can only intersect a parabola at two points on the curve. Like a stopped clock, AS can only be precisely correct for two instances in the course of playing a record. Why I stopped fretting.
Reed 2G magnetic antiskate
for the life of me, my REED 2G antiskate seems to defy me. Using the blank disc, no adjustment seems to keep the arm from skating inward....I have tried some other, audible tests of antiskate, and cant detect any change....any advice or thoughts?
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this pattern of highest, decrease and then increase in skating force as the arm tracks across the record is why, I imagine, the magnetic, varying systems have been developed, as opposed to a constant force....but still, just an approximation at best, as every LP/cartridge/stylus will be slightly different....and, practically speaking, there is certainly a difference between physics theory and what is audibly noticeable
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a brainiac, was involved so Reed’s ’attract for a while’ (magnet forward of the pivot pulls arm out) then reduce (to zero? arm pivoted/centered between the +/- magnets), ’repel for a while’ (magnet behind the pivot pushes arm out) is it’s own parabola? That’s supposing I am guessing right, which I wouldn’t put money on. I can’t wait to find out what OP learns from Reed. ........................................ WAM quantifies AVERAGE (data from the hundreds of arms/cartridges they have worked on) anti-skate needed as a small Percentage of Tracking Force long arms , they say outer avg needed is 9% of VTF; inner avg needed is 7% of VTF, thus try for an average of 8% shorter arms, the average needed is 11% It’s tempting to say 12" 8%; 11" 9%; 10" 10%; 9" 11%, just because it fits the averages and imagined logic, reminder, averages, like shoe size, or desk height, is wrong for everyone above or below that make the computed average, i.e. averages are wrong for most of us. He sums it up, Anti-Skate, what we can do is "At Best An Approximation" ..................................... I think, using my ears and the 3 guitarists, I am now going to use only the last track which is the inner location, and that is by average close to the outer, a speck more rather than less if in doubt. .............................. Just to repeat: Steve and Ray Leung at VAS told me a few times, and Peter at Soundsmith has stated that the MAJORITY of the cartridges they rebuild have excessive wear on one side, most often the outer edge, thus the MAJORITY have too much anti-skate.
I agree the SME 3009/3012 seem to get it right, but all other arms I have messed with, both the tracking dials and anti-skate dials have been proven inaccurate by more accurate or revealing tools/methods.
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TW Acustic let’s you see the moving part, it is simply a threaded piece made of ____, the magnets are concealed in the arm. The counterweight and it’s threaded rod are non-magnetic material https://www.tw-acustic.de/tonarme/raven-9-5
their headshell is fixed, but the fitting somehow allows azimuth adjustment they say
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There is no way the magnetic AS devices we see on some tonearms could be so sophisticated as to vary the AS in magnitude to suit the varying magnitude of the skating force. That is wishful thinking. Since, all other things being equal, magnetic force follows an "inverse square law" (as do forces due to gravity, electric charge, etc), it is possible that magnetic AS force varies in that manner as well, across the LP surface. Which means it varies inversely as the square of the distance between the magnet and the thing it is attracted to, be that another magnet or a ferrous target. |
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