Setting anti-skate

Doug,

Why are the widely spaced tracks better?

Rich

Dougdeacon...Setting antiskating using a highly modulated groove does make sense. Such a groove is when mistracking will occur. Less modulated grooves will be OK with antiskating a bit high.

Its not that widely spaced is better. The widely spaced tracks indicate that these are very highly modulated (in other words very difficult to track). So, presumably, if anti-skating is optimized, the cartridge will track better through these grooves. But I don't think I agree that trackability is the purpose of antiskating. Its an indirect by-product of the purpose: to provide equal force at both sides of the groove. So we need to come up with the best way to observe that equal force is indeed being applied, particularly for our favored low-compliance cartridges with which we cannot really see the deflection. What about installing a cheap high-compliance cartridge, and using it to calibrate the anti-skaing method? Track this cheapo at exactly our intended force, and note the deflection when the needle is dropped on the record, at various points on the record. Then adjust antiskate, and switch cartridges.

Using a record without grooves to check anti-skating is not "against the law of physics". Think about it a bit more. The friction of the record against the stylus tip is what causes an inward force upon the cartridge. Anti-skate attempts to balance this with an equal-and-opposite mechanical force. With no anti-skate, a grooveless record will pull the needle inwards, and this motion will be obvious. With too much, the mechanical force will pull it outwards. If these are equal, then the arm-and-cartridge will not move in either direction. This concept was well accepted in the 60s and 70s, exactly because it IS consistent with the physics of the forces applied. Now, is it perfectly accurate...no... because the friction of two groove walls is not identical to the friction of a flat surface. But if there is no force side-ways, because all side forces are equalized, then it is ONLY the down-force that is causing friction. Furthermore, think further. The variation of skating force must be extremely variable as the arm moves across the record, because velocity becomes slower as we approach the center and tracking angle varies. So, any mechanical anti-skate device cannot achieve accuracy across the entire record. Whatever we settle upon is a gross approximation, no matter how we measure it.

Rmaurin wrote:

Why are the widely spaced tracks better?

Because skating forces vary across the record. Measuring at just one place cannot account for this. Measuring on outer, middle and inner grooves lets you identify an AS setting that balances this variable.

Eldartford wrote:

Setting antiskating using a highly modulated groove does make sense. Such a groove is when mistracking will occur.

Skating forces vary with groove modulations. Adjusting AS for unrealistically modulated grooves will result in excess AS for real grooves.

... and:

Less modulated grooves will be OK with antiskating a bit high.

I'm sorry, but this is misguided. If AS is set too high then you're intentionally causing uneven groovewall pressures. This will result in premature wear of both your vinyl and stylus, on the R channel side of each.

Further, if your rig and system are sufficiently resolving it's easy to hear the effects of excessive AS. Warjarret has already done so. If your rig or system cannot resolve those sonic effects it doesn't mean they aren't occuring at the stylus/groove interface. It just means your rig or system can't reproduce them.

Warjarret,
By "widely spaced" I was not referring to individual grooves and the spacing between them. I was referring to tracks 1, 4 and 8(?) being spaced on outer, central and inner grooves. For why this is significant, read my response to Rmaurin above.

BTW, no one questions that skating forces occur on blank surfaces. It's just that, as you said, they are a poor approximation of the skating forces created by a stylus riding inside a modulated groove. Yes, AS is always a compromise. I've said that a million times. But what's the point of choosing a compromise based on a totally unrelated operating environment?