Remove your bias for better sound

I've always had a hard time understanding how zero anti-skating force can result in optimal sonics. It will cause the cantilever to deflect toward the outer edge of the record, as viewed from the front of the cartridge while the record is rotating. Especially (I believe) if the cartridge has relatively high compliance. How can that improve sonics? Unless:

(a)It compensates for some internal misalignment in the cartridge. Or,

(b)The cartridge is designed with the expectation that it will be used that way. Or,

(c)The arm is applying some amount of anti-skating force even when it is adjusted to zero.

Can anyone provide a technical clarification on this?

Regards,
-- Al

Thanks very much, Doug. I was hoping you would bring your expertise to bear on this.

However, although my experience is limited to relatively high compliance moving magnet and moving iron cartridges, my observations have been inconsistent with your first two paragraphs. Every time I have installed a cartridge, in most cases using the Magnepan Unitrac tonearm I have had since the 1980's, I can easily vary cantilever deflection, as viewed from the front of the cartridge while the stylus is in the groove of a rotating record, both to the left (with excessive anti-skating force applied), and to the right (with little or no anti-skating force applied). This is all with respect to the angle of the cantilever when the stylus is lifted off of the record, which is nominally straight ahead.

With too little anti-skating force applied, the effect is as if skating force is acting on the tonearm, rather than on the stylus.

And what I have observed has nothing to do with the suspension taking a "set." The deflection I have seen as anti-skating force is adjusted occurs immediately and repeatably, in either direction, and occurs only when the stylus is in the groove of a rotating record.

Deflection of the cantilever could only occur if the tonearm resisted the inward pull of the groove. An arm with zero A/S applied furnishes almost no resistance to the inward path the stylus wants to follow.

I see what you are saying. Perhaps the key to reconciling all of this is how close to zero "almost no resistance" is, for the particular arm? With cartridge compliance also presumably being a factor. Although an explanation based on bearing resistance would still leave me somewhat puzzled with respect to deflection in an outward direction.

Best regards,
-- Al

11-08-12: Dover
Although the stylus is being pulled inline with the cantilever, there is a resultant force on the arm itself pulling the arm toward the centre due to the cartridge offset and overhang. Now the arm also has an inertia resisting this inward force proportional to its effective mass. Therefore there is more than likely a conflict of forces on the cantilever - inward force applied from the offset & overhang versus inertia of the arm. To my mind the amount of antiskate required is that required to keep the cantilever in line with the groove. I very much doubt that this would be 0, but it would also be influenced by the horizontal compliance of the cantilever pivot.

Thanks very much, Dover. That all makes sense to me, and is consistent with the observations I described. Which would say that as anti-skating is fine tuned by ear, a visual check should also be performed to confirm that no perceptible left or right cantilever deflection occurs, as viewed from the front of the cartridge, as the stylus enters the groove of a rotating record. Perceptible deflection occurring most readily, as a result of non-optimal adjustment of anti-skating force, in the case of high cartridge compliance, low tonearm effective mass, and also, if my understanding is correct, low cartridge weight. All of which is what I happen to have, relatively speaking.

FWIW, with my Soundsmith re-tipped Grace F9E Ruby and my undamped Magnepan Unitrac unipivot arm I've settled on an anti-skating force equal to about 56% of the arm manufacturer's recommendation. I suspect that their recommendation is based on setting anti-skating force equal to tracking force, which is a ridiculous notion IME.

Doug, thanks also. The concluding sentences of your two posts above seem to sum up the bottom line -- as is usual in audio, things are system dependent.

Best regards,
-- Al