A new way of adjusting anti skate!

Regards:

Published to AES, 1967: "The Skating-Force Phenomenon. What it is, how it's measured, and its influence on performance of modern, lightweight phono cartridges." JAMES H. KOGEN ...

6 pages

PDF, copy/paste Google search:  "1967 paper by Shure’s Chief Engineer James Kogen." 

Found at audio-creative.nl. 

* Skating decreases towards the spindle as centripetal force (est. influence  elsewhere @ 5%) increases.

* Downforce, stylus profile, depth of groove and groove velocity are factors. (Spindle to pivot distance is a consideration.) 

* Increasing or decreasing skating force will influence wear to either inner or outer grooves, as well as wear to either the left or right bearing surface of the stylus. 

(Wallytools- Shure devised a neat tonearm mounted device to measure skating. It's described in the Kogan paper.)

Conrad Hoffman has thoughts on the subject, http://www.conradhoffman.com/AntiSkate.htm

Descartes on First Principles: "It will accordingly be necessary thereafter to endeavor so to deduce from those principles the knowledge of the things that depend on them," Although Descartes never spun an LP it is likely the philosopher would agree that although it might fit many, one shoe doesn't fit every foot.

When skating is balanced, left and right channels are hypothetically equally amplified. The "phantom center channel" phenomena emerges. Very minor adjustments to anti-skating will move soundstage center left or right.

Through the early 1970's, VTA at 15* was typical. Sometime around 1974 (IIRC) 22* VTA as standard was agreed on. Later investigation found there was still a discrepancy of several degrees VTA/SRA from one manufacturer to another.  As with correctly aligning an advanced profile stylus, azimuth or SRA may vary. Stylus to cantilever fitting is not always precise. Setup by the book is sometimes an approximation, none the less a good place to begin. Presuming ones gear is in good condition, listening and knowing what to listen for should confirm the best practical application. 

Peace,

Timeltel, it’s great to hear from you. Hope you’ll stay around.

what with all it’s problems, drawbacks, and impractical aspects, it’s a wonder how good vinyl can be.

Dear Wally, From your excellent videos (excellent in terms of clarity and presentation), I get that when the line from the pivot to the stylus is perpendicular to a line drawn on the radius of the LP, there will be no tracking force. That is exactly what happens at the single null point one can achieve with an underhung tonearm. I also get your evidence that headshell offset angle has nothing to do with the skating force, but that is shown for a spherical stylus on a groove-less LP. (By the way, where did you get what appears to be a Columbia 6-eye LP with no grooves?)

Have you repeated the experiments with either a non-spherical stylus or an LP with grooves, say a 1kHz steady signal? I realize that with grooves one would not so easily be able to visualize the skating force. As to the video in Russian, the set-up is cool but the dialog is unintelligible to me.

Where did I miss your definition of "Effective Moment Arm"? I haven’t a clue.

From the point of view of pure physics, I still don’t see why an overhung tonearm with an offset headshell, aligned according to any of the popular algorithms, would not exhibit a skating force at either of its two null points that is for that moment due only to headshell offset angle. Maybe you need grooves and/or a non-spherical stylus tip to show that. I do agree with you that a lot of so-called authorities have run to far with that ball, saying that headshell offset is THE cause of skating, which I agree it is not.

Regards Lew(m):

Thanks for the gracious "hello".

You wrote: "a lot of so-called authorities have run too far with that ball, saying that headshell offset is THE cause of skating". I too have heard that. One might ask those audio gurus what would be the effect if the headshell were turned away from the spindle, would then skating force direct the arm away from the label? An amusing proposition. 

It seems to me that no matter which point of the compass the headshell is aimed or however the tonearm is configured, the axis from stylus to pivot (and as you mentioned, over/underhang) is the primary  consideration.

Peace,

Answers to Lewm and timeltel questions are HERE. Be SURE to download attachment at bottom of page.

There is no centripetal force vector that consistently aims toward the spindle. It has been a long time since I read Kogen, but if he claimed the existence of centripetal force in skating then he either was referring to a condition similar to the one in my first slide of the download (depiction of the treadmill), which is a minor component of skating force, or he used the term in a figurative sense, not literal.

The profile of the very tip of the stylus will have no impact on the force vector directionality but may have an impact on coefficient of friction.

By the way, Wally passed away in 2018. This is J.R. Boisclair. I did not use my name as my moniker not because I am "hiding" but because I felt I should make it clear that I have a direct interest in this industry and it would be best if you knew who was doing the posting. Most people know WallyTools and fewer know my name. Cheers!