KentTeffeteller
Gimpus Stereophilus!
I use a Stanton 681a tracking at around 1.75 grams without issue. With the EEE-S I can understand why anti-skating is necessary on some arms. The AR XA never had it either for one.
Arms without anti-skating (ATP-12T)
- Thread starter gouzos
- Start date
marcmorin
RIP 1953-2020
Because that crude looking arm has a near perfect neutral lateral balance. No torque = no skate.
Pio1980
AK Member
The way to observe skating is putting the stylus down on a blank no-groove disc at various radii. A 'straight' arm like a scratch arm will move either inward, outward or stay put depending on where it is set but with highly variable tracking angle error. An offset arm with properly set overhang distance will always move inward due to skating force but with greatly reduced angular tracking error. This blank disc cannot be used to accurately set A-S BTW as it does not duplicate actual groove tracking cdx.
Because an pivoted arm will track and trace properly does not mean that this is theoretically optimal for equal tracking force on both groove walls as it is not, sufficient tracking force to allow accurate tracing under all practical cdx will compensate for the inevitable unequal wall-to-wall tracking force.
Straight-radial linear arms of course exhibit no skating effect or significant angular tracking error at any point on the disc.
Because an pivoted arm will track and trace properly does not mean that this is theoretically optimal for equal tracking force on both groove walls as it is not, sufficient tracking force to allow accurate tracing under all practical cdx will compensate for the inevitable unequal wall-to-wall tracking force.
Straight-radial linear arms of course exhibit no skating effect or significant angular tracking error at any point on the disc.
Hi, the skating is nothing to do with the static balance of the arm really, it is a product of the rotation of the record on the stylus. This paper has a clear (IMO) explanation of how the skating force is generated by a spinning record. It does, however, depend on the tonearm geometry.
For the record (pun intended
) the paper also gives clues on why adjusting the antiskating with an blank disc is a flawed method. The skating force depends linearly on a friction coefficient which is completely different in a groove or on a flat surface. Use a proper test record, or trust the scale on your tonearm.
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gusten
Addicted Member
Hi, the skating is nothing to do with the static balance of the arm really, it is a product of the rotation of the record on the stylus. This paper has a clear (IMO) explanation of how the skating force is generated by a spinning record.
For the record (pun intended
I agree that static balance has nothing to with skating force. But I don´t think the blank disc method is flawed at all. When I have tested different spin down time with blank disc, silent groove and mudulated groove, there is not really any difference. That means that the friction force is rather similar no matter what we play, and doesn´t depend much on tip area.
gusten
Pio1980
AK Member
Doesn't it seem counter-intuitive that the contact patch area wouldn't be a frictional factor affecting degree of stylus drag and therefore degree of skating force?
gusten
Addicted Member
No opposite really, friction force is only dependant on normal force and friction coefficient. On the other hand, what do we really know about the area, nothing really.
gusten
Hi gusten, have a look at the figures in the paper above. Admittedly it doesn't show a disc without a groove, but the difference between a silent and modulated groove is pretty self-explanatory. Remember that we are talking about just grammes-force here, probably not enough to noticeably brake the platter, but quite enough to change the skating force to compensate.
gusten
Addicted Member
I am very sure there is no difference in friction force, I have measured this extensively.
gusten
Edit: What I mean is of course that the force vector parallell to the groove is the same.
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When you look at it the difference is taken into account in the two scales of the typical good AS dial, one for conical and one for elliptic. Of course it is just a rough estimate, it doesn't replace proper setting using a test record, but it has its use. Besides I had already noticed that stylii tend to need a higher AS setting as they grow old. That would be a plausible explanation.
I'm sure, but did you check the precision of your measure? Are you sure you can measure the very few gf of difference (most probably even less than that nowadays) between a silent groove and loud modulation? I ask because physically it seems really unlikely that there is no difference at all.
Pio1980
AK Member
I thought this device had decisively proved otherwise.
http://www.sutherlandengineering.com/timeline
gusten
Addicted Member
For different styli we have different lifting effects, which are different for sphericals than for elliptical than for microlines. What I am talking about is a needle that can trace the modulations as good as it gets, then there is no difference when using that needle in different situations. The friction force will be the same.
gusten
gusten
Addicted Member
If there is a difference it certainly wouldn´t matter when we talk about skating forces.
gusten
marcmorin
RIP 1953-2020
You must have missed this paragraph in the paper you refer to......
......"The skating force was found to be a torque producing clockwise rotation force in a horizontal plane about the vertical pivot of the arm"......
No mass imbalance in the horizontal = no torque in the horizontal.
You cannot have torque without mass.
Adding mass to off set that is exactly what a "hanging weight" antiskate device does. That system "cures" lateral imbalance.
adding a spring to produce an equal amount of torque in the opposite direction is what a spring type antiskate does.
If the arm has a natural lateral balance it will not skate. You can create an arm as such, or you can create a sytem to create natural lateral balance.
Friction is not an additive force, it is a subtractive force. The only things created by going from static friction to kinetic friction is heat, noise, and a void in energy (moment of motion) That energy void has to be filled.
cgutz
AK Member
This is the method I used to determine the amount of antiskate needed. I find on my Kenwoods (KD550 and KD5070) I only need about 40% of VTF (based on the AS scale markings) and a mono record balances perfectly, and any groove distortion is minimized with proper setup. Visually, deflection of the cantilever while playing is also minimized.
arcorob
Addicted Member
Exactly...
This is why I am so adament about why anti-skate should be used..there is truly an audible difference not to mention what lack of or too much does to a microline stylus.
It has been pointed out that broadcast arms and such and the AT arm mentioned dont use anti-skate...But generally they are massive (23gram for the AT) and are designed to track at 3 to 4 grams...
Glad it worked on your Kennies...Nice tables !!!
This is why I am so adament about why anti-skate should be used..there is truly an audible difference not to mention what lack of or too much does to a microline stylus.
It has been pointed out that broadcast arms and such and the AT arm mentioned dont use anti-skate...But generally they are massive (23gram for the AT) and are designed to track at 3 to 4 grams...
Glad it worked on your Kennies...Nice tables !!!
arcorob
Addicted Member
Hypothesis
its been mentioned that setting skating force is only an approximation because the closer one gets to the center spindle the greater the force required would need to be, TRUE?
In that case, the ultimate anti-skate would use a weight and string, with the string over a small bar protruding from the arm pivot. At its closest point (outer track), the bar would be shorter because its closer to the the string and weight.
As the arm moves inward, the bar pivot extends creating a larger force (sort of like when you move a counterweight back on an arm). The further the arm moves, the more weight is incremented because as with all levers, the longer the lever, the greater the force using the same mass.
Yes? I would love to draw a picture of this..its simple.
its been mentioned that setting skating force is only an approximation because the closer one gets to the center spindle the greater the force required would need to be, TRUE?
In that case, the ultimate anti-skate would use a weight and string, with the string over a small bar protruding from the arm pivot. At its closest point (outer track), the bar would be shorter because its closer to the the string and weight.
As the arm moves inward, the bar pivot extends creating a larger force (sort of like when you move a counterweight back on an arm). The further the arm moves, the more weight is incremented because as with all levers, the longer the lever, the greater the force using the same mass.
Yes? I would love to draw a picture of this..its simple.
gusten
Addicted Member
Of course it would. Read the paper.
Just to be clear, what I have measured is only with a Shibata stylus. There is no difference in platter spin down time between all different records I have used, blank, grooveless, testtones and different music. No more difference that there normally is depending on friction coefficient, which can vary from record to record.
gusten