Uni-Protractor Set tonearm alignment

Dear John,

You said "this force (antiskate) has to increase as the arm approaches the center." How about from the outermost of the lp toward the center? How should the antiskate work for a pivot designed tonearm ?

Apologies to the original poster Downunder, but I think this is the best kept secret in analogue.

Regards,

Dear Jazzgene, dear Thuchan, dear Mesael, please allow me to briefly bring some "certainty" into this "vague" topic "anti-skating".
Gene and Thuchan - your observations regarding the VPI and SAEC tonearms are correct and backed by physic.
A brief summary of skating - it's whereabouts and effects in analog audio.
The notorious "skating force" is a result of the friction in the inner groove wall in conjunction - and this is the very important point now ! - with the offset angle of the pivot tonearm, the stylus' contact area's shape and the VTF.
It is an un-linear force by nature ( in a given set-up with a given cartridge and a singular given pivot tonearm ), as it is in conjunction with the position on the tangential error curve, the distance (= radius of groove wall) towards the inner label and the VTF.
The higher the VTF - the lower the skating force.
The longer the effective length of a given pivot tonearm - resulting in smaller offset angle - the lower the skating force.
The is no skating force in a tangential tonearm at all.
The friction on the inner groove wall is the result of the breakdown torque in a tonearm with an offset angle - a tangential tonearm (at least so far ..) has no offset angle.
If you encounter skating force in a tangential tonearm, then there is a serious misalignment of the tonearm and/or your turntable isn't leveled ( or there is a stream of air aiming at your tonearm .... ).
The breakdown torque in a pivot tonearm is an inevitable force. It can be addressed, but this is rarely done.
To compensate skating force in groove tracking - unlinear by nature - with a linear compensation is futile from the start. Futile in the sense that you fight one evil with another. In most 9" tonearms working with high compliance/low VTF cartridges you will need anti-skating, as this dreadful effect-force is very high here.
A tonearm with 12" (= small offset angle = lower breakdown torque) and with a low compliance cartridge with VTF of 2.5 gr and higher will most likely make anti-skating obsolete. In any case the resulting force is much smaller than with a 9" tonearm and a MM working with 0.8 to 1.5 gr VTF.
Then there are a few tonearm designs whose designers addressed the breakdown torque where it occurred and created tonearms with very low skating force applied to the stylus.
Cheers,
D.

Dear Mesael, No ide what 'the best kept secret in analoque'
is but to my knowledge only the Sony PUA 237 has an ingenious antiskating construction which 'provide' different force depending on radius. All others have the same force everywhere as far as I know. If my quess is correct than the Sony solution should answer your question
'how should the antiskate work for a pivot arm'.

Regards,

Dear Thuchan, Jazzgen,
I mounted my 12” JMW memorial on an armpod and set it up on another table on weekend for the Jrs. experiment.

It took all of two minutes – no numbers or calculations - I put the cartridge in the VPI tonearm head - nice and straight the way I wanted it to be held - firmed up the bolts.

Then I rotated the JMW arm hinge and the armpod until it lined up perfectly with the VPI jig.

I have found that JMW arm works best for me with no turn of the wire.

Sorry to digress away from the thread theme.

Cheers Chris

Dear Nandric,

Not so fast. I'll show you examples of tonearms.

Anti-skate from outer grooves toward inner grooves:

Constant : Clearaudio Unify, and simple counterweight
with string

Increases: Clearaudio Satisfy, and those using spring, and
most of magnet design

Decreases : Morsiani.
Here's the link :http://www.morsiani.it/

So, which one is correct or none of the above ?

I'll wait for John. He's a designer,and seems knowledgeable.

Cheers,