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In Reply to: RE: Your personal experience notwithstanding,... posted by Lew on August 25, 2016 at 07:31:34
> What I am trying to get my mind around is whether increasing VTF would in fact always result in increased friction.That is very easy to test if you can get a vinyl record with a grooveless shiny flat surface. Simply adjust antiskating so the tonearm remains stationary and then increase tracking force without changing antiskating force. I think you'll find that friction always increases when tracking force increases.
Some test records have a blank band without grooves that you could use to conduct this test.
Another interesting test will show that friction does not change with platter speed. Again, adjust antiskating so the tonearm remains stationary on a grooveless vinyl surface and switch speed from 33 to 45 RPM. The tonearm will remain stationary because friction does not change when the speed of the vinyl surface underneath the stylus changes.
Good luck.
John Elison
Edits: 08/25/16Follow Ups:
I don't understand how the tip of the stylus (a part of the stylus that never touches the vinyl while the stylus is in the groove) riding on a flat surface has much (if anything) to do with the stylus contacting each side of the groove at the 2 contact areas, WRT skating force?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Fortunately, your understanding or lack thereof doesn't alter the laws of physics.
Best regards,
John Elison
Please explain.
When the stylus is in the groove there are two contact points. One on each side of the groove.
If friction is part of the cause of skating force wouldn't the friction be very different vs. the tip of the stylus contacting the flat vinyl?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
It's not "very" different. It might be different but it is more likely to be "very" similar. However, all stylus shapes will react differently, but it's often thought that the tip of the stylus against a flat surface will produce more friction than the stylus in a groove. That means there might be more pull from a flat surface than from a groove. It really depends on the particular stylus shape.
Even though there are two contact points when the stylus is in the groove, the force against each of the contact points is smaller than the force of the tip against a flat surface. For example, if you were tracking at 2-grams, the force of the tip against a flat surface would be 2-grams. The force against each wall of the groove would be only 1.4-grams.
Best regards,
John Elison
I will take that as a victory.
I got you to explain yourself instead of just "making a proclamation".
You make some very good contributions to the forum here but that doesn't give you the right to make "proclamations" without explanation.
Thank you very much for explaining yourself.
I still believe that setting AS using the flat surface method is a crap shoot. There are too many variables. (as you just admitted to, "all stylus shapes will react differently")
I'm not saying that I have a better method though.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
First of all, my analogy of a stylus tip on a flat vinyl surface compared to the stylus in a groove was not meant to suggest they would produce the same skating force. However, logic would suggest that both cases would react the same to vertical tracking force. Therefore, if you discovered that skating force always increased when increasing tracking force on a flat vinyl surface, it would be logical to believe that skating force would react in a similar way to tracking force with the stylus in a groove.
Secondly, with a special type of cartridge designed to measure skating force, it can be shown that even though skating force from a flat vinyl surface is not exactly the same as skating force with the stylus in the groove, the two are more similar than they are different. Therefore, I believe that Frank Schroder and Peter Ledermann have developed a reasonable method for setting antiskating using a flat vinyl surface. Personally, I have never found the perfect method for setting antiskating and I now believe that Frank and Peter's method is as good as any and better than most. Even you state:
> I'm not saying that I have a better method though.
The method I use for setting antiskating is to follow the instructions from my tonearm owner's manual. I set antiskating on both of my tonearms by turning the antiskating dial to the same number as the tracking force setting. When I test this setting by Frank and Peter's method, it normally comes out very similar -- almost identical every time. Therefore, if you don't have a calibrated antiskating dial such as with VPI tonearms, I believe the method presented by Frank Schroder and Peter Ledermann is perhaps the best method to use.
Best regards,
John Elison
Is a close approximation of the forces involved. You are probably within the margin of error when adjusting on the flat surface. The only possible differences are caused by the tip not being polished the same as the side of the stylus, and also the force needed to accelerate the moving mass of the cartridge, which is probably a tiny fraction of the kinetic friction.dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
Edits: 08/25/16
.
Have Fun and Enjoy the Music
"Still Working the Problem"
compared to the contact area the the groove is not that much rougher than the flat surface. so the coefficient of friction aka mu is probably the same within a tiny fraction. the whole idea with this constant is that it ignores the shape of the contact areas. you do not need to know that the contact surface is 10 sqrt micron or 10 sqrt feet. you know the vertical force, multiply it by mu and you got the kinetic friction force. There is a minuscule difference in forces when one has to accelerate the moving mass of the stylus assembly around the modulation but that is negligible compared to the kinetic friction. Newtonian physics is very well modeled :)
decided to add this tidbit.....
The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground. This makes sense, because if the area of contact doubles, you may think that you should get twice as much friction. But when you double the length of an object, you halve the force on each square centimeter, because less weight is above it to push down. Note that this relationship breaks down when the surface area gets too small, since then the coefficient of friction increases because the object may begin to dig into the surface. If that happens when you are in the groove of a record you have bigger problems than the skating force.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
Edits: 08/25/16 08/25/16
Penguin,
Thanks for posting this video. I'm frustrated by my inability to do the math even at this basic level, but I was able to follow it in this case and learned a lot.
Doug
"Note that this relationship breaks down when the surface area gets too small, since then the coefficient of friction increases because the object may begin to dig into the surface. If that happens when you are in the groove of a record you have bigger problems than the skating force."
The tip of the stylus is not meant to come into contact with the vinyl so "digging in" might just happen with the tip riding a flat surface. But, as has already been said, the shape of different styli will be different so it (the flat surface method of adjusting AS) is still a crap shoot.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
if no scratch on the smooth part, then everything else is the same as in the groove. So the kinetic friction force is closely equal. everything else is negligible.You are grasping your straws :)
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
Edits: 08/25/16
I was pointing out what Peter has already said.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
John, most of the time I would not second-guess your knowledge, but this time I must.
I've read more than one description of anti-skate that states the stylus in a groove is necessary since that creates the "pull". If that is the case then your suggestion to utilize a grooveless section would not be completely accurate.
On the other hand, if anyone still wants to experiment with a grooveless record, at least a couple of the Shure Test Records included a grooveless area and they are easily found in used record stores.
"The piano ain't got no wrong notes." Thelonious Monk
I think you've misinterpreted what you've read. The groove does not create the pull; it's the moving vinyl surface. Penguin explains it correctly in his post below. It doesn't matter if the moving surface is flat or grooved, there will still be friction when the stylus presses against a moving surface. Both Frank Schroder and Peter Ledermann recommend using a flat grooveless vinyl surface for setting antiskating and I agree with them.
"If one sets the stylus on a smooth surface of a record (at the end, in-between the run out grooves) �" the tip of the stylus has a drag on the surface that while not equal to, is "standardized" enough to allow it to be used to adjust the Anti-Skating. This is due to a calculation of "force per unit area" with consideration of the rheology of the material �" vinyl. Suffice it to say that since it has been reverse engineered and calibrated properly, this method works well. It then becomes an easy matter to set the A-S and observe the movement of the arm. For a given VTF (any amount of VTF) �" set the A-S so that the arm VERY SLOWLY drifts inwards when placed on the SURFACE (NOT IN A GROOVE) at the end of a record. "Contained in the above paragraph is the understanding that the "tip of the stylus" has a different "drag" on a flat surface than the two contact areas of the stylus when that stylus is in the groove.
Peter further states "Frank Schroder and I are of the same opinion about antiskating �" and that makes MOST records that provide an "anti-skating track" totally in error �" many are recorded at about 80-90% modulation -OR MORE, or have increasing levels of modulation as the track progresses and expect you to set the A-S force so that there is no distortion at all at any level of modulation (or equal amounts on both channels if the cartridge tracks poorly). "
Which makes it clear that he understands that the level of modulation in the groove changes the skating force.
"the tip of the stylus has a drag on the surface that while not equal to, is "standardized" enough to allow it to be used to adjust the Anti-Skating."
Which is not the same as saying that the tip of the stylus on a flat surface creates the same amount of skating force as a stylus in a modulated groove.
Peter is not making that case.
He, in fact, is explaining that even though the drag is different ("that while not equal to, is "standardized" enough") it still a good way to set the anti skate.
I believe that is debatable.
I think you should question your own understanding (not mine) of the laws of physics.
In any event it doesn't take an understanding of physics, it just takes some common sense.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 08/25/16 08/25/16 08/25/16
Regarding:
"Which makes it clear that he understands that the level of modulation in the groove changes the skating force. "
Not so. Average skating force stays the same.(Some claim that VTF is increasing, but it does not seem that anyone managed to measure it. Thus my opinion is that if there is a difference it is negligible.)
By your statement it appears that you misunderstand the purpose and how the test works.
Intent is to produce the same level of distortion in each channel which means that the force exerted at each grove wall is the same, which menas that the antiskating force is at an optimum value. Increased level is needed as different cartridges will mis-track at different levels.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"One must be sane to think clearly, but one can think deeply and be quite insane."
"Not so. Average skating force stays the same. Increased level is needed as different cartridges will mis-track at different levels."If I understand you correctly you are saying that, for the same amount of skating force, different cartridges need different antiskating force and a high level of modulation in the groove just shows this difference (between the cartridges) while not changing the skating force?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 08/26/16
Cartridge tracking capabilities differ, that is why increasing levels are needed.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"One must be sane to think clearly, but one can think deeply and be quite insane."
After I posted, I though that's what you meant.
Here's the problem I have with that thinking.
The purpose of AS is to counter the skating force and get the stylus to place the same tracking force on both sides of the groove.
If you have a cartridge that will track well even though there is not as much tracking force on the right side of the groove as there is on the left side of the groove then so be it.
But that's not the same as fully compensating for the skating force and having the tracking force equal on each side of the groove.
With the skating force properly compensated for the stylus will wear evenly.
Just getting the cartridge to track, even when the forces are not the same, will not ensure even stylus wear.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
That is why different modulation levels are needed, to practically force cartridge to miss-track evenly which indicates correct AS force.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"One must be sane to think clearly, but one can think deeply and be quite insane."
I've never said that the tip of the stylus on a flat surface creates the same amount of skating force as a stylus in a modulated groove. It depends on the shape of the stylus. Some shapes might come very close to having the same force.
However, I agree completely with Peter Ledermann and Frank Schroder when it comes to skating force and antiskating force.
Best regards,
John Elison
If "the tip of the stylus on a flat surface [isn't guaranteed to] create the same amount of skating force as a stylus in a modulated groove" and "It depends on the shape of the stylus" then the method is a crap shoot.
I am not saying that I have a better one. I'm just saying that it's a crap shoot.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
will not be the same, but for the experiment you can find the equilibrium and prove that speed is not a factor in the skating force. Only the surface and areas, the force and the surface quality determine the force between the stylus and the record (Fs=u*Fn) The friction factor u will change between the flat surface and record grove. Simple physics :). The skating force then is calculated using simple vector geometry.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
Edits: 08/25/16
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