AntiSkate-crooked Cantilever correlation?


This has been something that has been on my mind for some time now. I note how many forumites here typically now use little, to no anti-skate.

And, I've often wondered is anti-skate, or a lack of, is a possible cause to cantilevers eventually becoming cockeyed over time?

Common sense tells me, if a Stylus is "fighting" to stay in the groove, while the Arm wishes to pull one way, or another, that this might not be good for Cantilever "health"?

I would like hearing others thoughts of this topic? Thanks, Mark
markd51
Hi Mark,

Interesting question. To attempt a meaningful answer we must think about the two forces in question, skating and anti-skating. Let's consider skating first.

Skating force is a function of headshell offset angle on a pivoting tonearm. Assuming the cartridge is properly aligned (i.e., cantilever tangent to the groove), friction from the (moving) groove pulls directly down the line of the cantilever. Aside from in-groove modulations, which presumably balance out L vs. R in the long run, groove friction alone puts no lateral pressure on the cantilever.

Skating force occurs because the cantilever is not aimed at the tonearm's pivot point. Since the cantilever is aimed inward relative to the arm, from the tonearm's POV any pull down the length of the cantilever will make the arm want to swing inward.

Example: Hold your right forearm out straight in front of you, index finger pointed straight ahead. Tug on your fingertip; which way does your arm want to swing? Answer: neither way, because this "tonearm" has no offset angle. Now angle your wrist so your hand and index finger are pointed off to the right. Tug on your fingertip; which way does your arm want to swing? Answer: to the right, because this "tonearm" now has an offset angle.

Followup question: comparing each of the above experiments, how much difference was there in the lateral force being applied to the FINGER. Answer: except to the extent your arm resisted being swung to the right in example #2, there was no difference. In both cases all the force was exerted directly down the line of the finger.

Therefore, except to the extent the tonearm bearings are "sticky", skating force does not exert ANY lateral pressure on the cantilever. Groove friction pulls straight down the line of the cantilever and the tonearm just follows along. The above is true on all pivoting tonearms with offset headshells.

Now let us consider anti-skating. All anti-skating devices currently in existence apply an outward bias or force to the ARMTUBE. Since the outer end of the cantilever is fixed in position in the groove (by the stylus), any outward force on the armtube MUST be mediated by the cantilever and its suspension inside the cartridge.

To use the previous example: point your right arm and index finger as before, offset to the right, but put your elbow on the desk and also touch the surface with your fingertip. Using your other hand, pull your forearm to the left WITHOUT allowing your elbow or finger to move. What happens? Your finger is being stressed laterally and its "suspension" absorbs that force by allowing the inward angle of the finger to increase.

That is how all anti-skating mechanisms work, therefore, all anti-skating mechanisms tend, over time, to cause the elastic suspension in the cartridge to take a set with the cantilever pointing inward. How much of a set and how long before it appears will obviously vary with the amount of AS force applied, the number of playing hours and the nature of the cartridge suspension. But the basic principle does not change.

This is why, IMO, we see more high hours cartridges with inward pointing cantilevers than outward pointing ones. There is no force in a properly set up turntable that will cause an outward set, but causing an inward set is possible.

This provides an obvious caution against using too much AS. OTOH we must use enough for clean tracking of our toughest LP's (music, not test records). Beyond that, every rig is different, every cartridge is different, every listener's ears and listening priorities are different. I use zero AS now because it sounds better to me and because my cartridge, after 750+ hours of loosening up, no longer needed it to track even the toughest passages. That was not true when the cartridge was newer, when more AS and more VTF were required. Due to the ever changing character of elastomers, these parameters will always be moving targets on any cartridge with a suspension. In the end, the only firm rule is to always pay attention to what your rig is telling you.
The skating force, or the antiskating force, is small compared with the vertical force. The same elastomeric stylus suspension resists both directions of force. VTF will affect the stylus before skating has an effect (if ever).
Very true.

Skating force is unlikely to affect the suspension at all, for the reasons I described. OTOH, ANTI-skating force is not necessarily small. Some tonearms allow you to apply quite a lot (though rarely more than ~10% of VTF).

Anti-skating and VTF can both effect the suspension, but I agree VTF necessarily has the greater effect. Cartridge suspensions collapse downward faster and and farther than they collapse sideward.

Of course some cartridges quote different compliance figures for vertical vs. lateral forces, so they may have different elastomers for the different planes. Another fly in the ointment!
Very interesting ideas about anti-skate Dougdeacon. I put anti-skate dial close to the same number as the tracking force. I then use my ear to dial it in, using the principle, "if the sound is better on the inside tracks, you have too much anti-skate". When I get real close to the correct amount of anti-skate, I throw out all rules. I then ask myself if I am more excited about listening or less, if I move the anti-skate incrementally. Sometimes, I sleep on it. The anti-skate is now set. Now, this does not apply to uni-pivots or cartridges that suggest less anti-skate. Markd51, have you had an experience where the cantilever has been canted over time?
Mmakshak,

You actually read all that?! Just to be clear, all that high-falutin' crap was just a longwinded "not likely" to Markd51's question regarding cantilever/suspension canting. Everyday playing is much simpler than that, thank goodness!

Like you I adjust AS (and VTF, VTA, and azimuth) by ear. No scale or dial can tell us what setting will produce the best performance from any particular arm/cartridge combo. Numbers get us in the ballpark or help us return to a setting we know was good, but that's about all.

The maker of a tonearm has no idea what cartridge might be used on it, so the numbers on the AS dial are pretty arbitrary. My tonearm doesn't even have such numbers and I'd ignore them if it did. IME starting where you do typically applies excessive AS, but you gotta start somewhere. I prefer to start at zero and add as much AS as the cartridge needs, but to each his own. It's where you end up that really matters.

I confess I don't understand your statement that "if the sound is better on the inside tracks, you have too much anti-skate". Where did you get that idea?