Should I disable anti skating when doing alignment... ?
sure, you have to
Zero anti-skate for alignment purposes.
Whenever you hear distortion, test track or otherwise, always remember the Left channel is on the Left (inside) side groove wall, and the Right channel is on the Right (outside) groove wall.
Anti-skate pulls the arm to the outside. So too much anti-skate will pull the arm out too much, leaving too little tracking force on the inside, and so the left channel will distort. In the reverse, too little anti-skate gives too much force on the inside, and so the outside Right channel will distort.
Skating forces are generated by the angle of the cartridge being dragged through the groove. Therefore, the higher the volume, the bigger the groove amplitude, the greater the drag and therefore the greater the anti-skate needed to counter it. Notice then this changes constantly depending on the music. So if you use a test LP and set anti-skate high enough to track really high amplitude test tracks, do not be surprised if it is too much anti-skate for a lot of your music. You may or may not notice a problem. Usually people only notice problems at the extremes. Just something to keep in mind.
All of this stuff is childishly simple once you learn how to think it through. Where it gets hard is when a million audiophiles start telling you all kinds of stories and getting you trying things without ever explaining so you understand why. Once you understand why the questions evaporate, you know the answers without even asking.
Millercarbon hit the nail on the head. Whenever you do anything to the arm except adjust anti skate you neutralize the anti skate.
@ozzy62 , I beg to disagree. Zero anti skating never sounds better but too much is just as bad. In the absence of an accurate measurement device such as the WallySkater or my Gizmo (see my system page, last picture) the anti skate should be set so that the arm drifts slowly towards the center of a groove less record. You can also use the runout area if you are quick.
MC's thoughts are a minor consideration in thinking about the magnitude of the skating force. The most important cause of the skating force (after friction) is the tracking angle error, which is varying in terms of degrees of angle, all across the surface of an LP. And it is never zero, for any of our conventional pivoted tonearms that have an offset headshell, even at the two null points you can achieve if you align the tonearm according to any of the known algorithms.
The movement of the stylus in the groove generates a friction force. If the vector direction of that force were to be straight back along the cantilever, and if the cantilever were to align with the arm wand going all the way back to the pivot, there would be no skating force, regardless of the tortuosity of the grooves or the ups and downs of the music signal. But that never happens with our pivoted tonearms; there is always an angle of error. That generates the side force. If you want more on this subject, I will try to help, but otherwise, I don't want to put anyone to sleep. Think of the little red wagon you had when you were a kid. It had four wheels and a pull handle that was attached to the axle of the front pair of wheels. Remember what it was like to try to keep the wagon alongside of you while you dragged it down the street? There was an aberrant side force that you had to correct for. That's the same idea as skating force.
OMG sorry but it has nothing to do with the angle of the cantilever. The skating force that pulls the arm towards the center is a result of not being tangential. It has nothing to do with the offset angle of the head shell, or the cartridge, or the cantilever, or the stylus, or any of that.
This is why linear trackers are also tangential tracking. A pivoted arm would have zero skating force IF AND ONLY IF it is tracking tangentially. But since the arm is pivoted this can happen only at one point.
Turntables and tone arms are actually childishly simple devices, literally as simple as a teeter-totter. You just have to stop and look at them closely to see what is going on. Please, please, PLEASE do that, and not get too caught up in other peoples stories about what is going on.
When you set up and align the cartridge, there should be no anti-skate. There is no need for it since the outward force should be just enough to offset the inward pull.
According to cartridge design and engineering experts (I'm not one), most arms are set up with much to much anti-skate. It's obvious when a cartridge stylus is examined through a microscope. One side, the one that rides against the out edge of the groove, is more worn than the inside edge, the surface of the stylus closest to the record label. of the stylus.
The longer the arm, the lower the anti-skate force. I have been using only 12" arms for a long time and exert almost not anti-skate force. My cartridges seem to wear evenly.
MC, do you read what you write? "OMG sorry but it has nothing to do with the angle of the cantilever. The skating force that pulls the arm towards the center is a result of not being tangential. It has nothing to do with the offset angle of the head shell, or the cartridge, or the cantilever, or the stylus, or any of that."
It is the cantilever that must be tangent to the groove, but even then, in a conventional pivoted tonearm which has headshell offset, you won't have zero skating force even at the two null points. First you disagree with me, and then you repeat pretty much what I said, using different words. The magnitude of the skating force has a great deal (not "nothing") to do with headshell offset angle and the cantilever. But headshell offset angle is the dominant cause of the skating force only at the two null points, where the cantilever IS momentarily tangent to the groove, but there is still a side force owing to the fact that the pivot point is offset. At all other points on the surface of the LP, the cantilever/stylus is not tangent to the groove, and this plays an additive role in determining the magnitude of the force, in the vector algebra sense.
Everything to you is simple, except sometimes you are wrong in your simple explanations, so maybe not so simple on those occasions. On this occasion, you and I are not really at odds, but you cannot see it. Or, to paraphrase something that Einstein actually did say, a hypothesis to explain a phenomenon should be simple as possible, but not simpler.
Before we all start getting into a major urinary tract exercise, why not read the results of studies and observations from actual cartridge manufacturers. As a start, I suggest reading Peter Ledermann's comments:
Beats me how you guys can argue over such a simple and obvious bit of physics.
Ledermann's explanation is correct.
He mentions using the unmodulated run-out area of the record to observe scating activity.
This is better done with an entire unmodulated side of a record. These are often present on MFSL 45rpm reissues. Drop the stylus at various positions on the revolving record surface and observe how strongly and quickly the skating force pulls the arm towards the centre. Then add anti-skating and re-test. Adjust the anti-skating force until the best result is obtained in maintaining the arm most nearly stationary at different points and you will have the best amount of anti-skating to equalise the forces on each side of the groove.
Ledermann mentioned in passing that parallel tracking arms are complex and expensive and kind of excluded them on that basis. I agree that many don't work very reliabily and are difficult to set up and maintain settings. My Simon Yorke Aeroarm (an extremely rare piece I am fortunate to have, thank you Simon) works very well and cost one-quarter or less of the price of the top pivoted arms that are now $50,000 and more. I know which I'd rather have.
I use the unmodulated side to set the lateral levelling of my plinth on the fly using a fine screw adjustment, so that the arm remains stationary on a revolving record. Lateral levelling is critical for parallel trackers and this method is waaayyy more accurate than using a spirit level.
You should NOT have the antiskate on or connected while making alignment adjustments. That is last step. In adjusting your anti skate, find a record with lots of dead wax near the label. Place stylus in the dead wax and watch how quickly or slowly the stylus moves toward the label/spindle. It should move gracefully, not too quickly and not too slowly. Usually the recommended position on the rod will coincide with your cartridge tracking force. The very outer rung is the most antiskating, while the rung nearest to the pivot is the least. So, you only have three options as there are only three rungs to hang the fishing line from.
Also, listen for distortion in right and left speaker...if your hearing it in the right, you have too much antiskating...if in left, you have too little...
@bpoletti - Thank you very much for the link. I found Ledermann’s explanation very informative. It’s funny how simple good science usually is. I used it last night to easily reset the anti-skate on my P6.
@clearthinker - I’m pretty sure scating is what one of the other posters was doing in the thread, as usual ;-). But seriously, totally agree that an unmodulated side would greatly simplify and increase the accuracy of Ledermann’s process. I went to the MFSL website but was unable to quickly discern which records would resemble your remark. Could you name a few that have an unmodulated side? BTW, I was unfamiliar with that website. I can see that they will be separating me from a considerable amount of my $s going forward, so not sure whether to thank you or curse you for that nugget ;-).
Of course Michael Fremer totally disagrees with Peter Ledermann and Frank Schroder. However, Michael Fremer is wrong when he asserts the friction on a groove less record is lower than in a normal groove. It is higher.
@clearthinker, The aeroarm is just as bad as any any other air bearing arm. It's horizontal effective mass is way too high. This causes the cantilever to oscillate side to side. Damping helps somewhat but still. You can prove this to yourself. Find a record in your collection that was drilled off center. Play it and watch the cantilever it will move side to side. It may be hard to see if you are using a very stiff cartridge like a Koetsu but then you will have a vertical mismatch. With a properly tuned pivotal arm you will never see the cantilever move unless the bearings are shot. If you are determined to have a tangential arm check out the Schroder LT or the Reed 5T, they side step this problem.
The best way to set anti skate is to measure it. It should be 10% of the VTF +- 1%. The only two ways I know to do this are with the WallySkater
(very expensive) or my Gizmo (dirt cheap, see picture my system page)
I will not chase you for patent infringement if you decide to make one yourself. The only important part you have to buy is the instrumentation bearing. Ceramic is the best. Otherwise, you could make it with some scrap wood, a scroll saw and a drill. If you want to wait I will probably sell it to a company like MoFi once the patent is pending.
There appears to be some confusion about the cause of skating force. If the cause is primarily the cantilever being not tangent to radius of the record (i.e., cantilever to perpendicular to a line drawn from the spindle to the point of contact, then skating force would be near zero at the two null points and would reverse direction as the null point is crossed; that does not happen. Skating force comes from the stylus dragging in the groove. That force is largely along the line of the cantilever (very slightly to the left or right of directly on line when not at the null point). Of course it also varies from directly along the cantilever when playing different parts of a waveform, but still, it is primarily along the line of the cantilever. The drag is pulling the cantilever. If the cantilever is pointed directly at the tonearm pivot, there would be no left or right bias to such pull. But, that is not the case because the headshell (and therefore the cartridge) is at a very substantial offset angle and points far to the right of the pivot. This is the cause of the skating force.
You can demonstrate this for yourself by pretending your arm is a tonearm. Put your elbow on a table (this is the tonearm pivot. Hold your arm and wrist straight out and now pull on your middle finger (this is the equivalent of drag pulling on the stylus and cantilever). Your arm should go nowhere. Now bend your wrist at an angle (like the kink in your tonearm) and pull straight back on your middle finger. Your arm will move inward, just like a tone arm does when tracking a record.
Ledermann's technique is not meant to exactly simulate skating force drag. It is something he developed as a proxy for roughly estimating the amount of antiskating force that should be applied. ALL approaches are just rough compensation, which is better than nothing, but far from perfect. It is also very easy to apply. He makes the case that using test records to find the point where the cartridge mis-tracks in one channel to determine whether to apply more or less antiskating force optimizes the setting only under extreme conditions, but, those conditions happen very briefly so the rest of the time one is applying too much antiskating. I think his approach makes sense. A similar approach is suggested by a cartridge manufacturer (I think it is Lyra) in their set up instructions. They recommend looking at a cartridge from the front and then cuing the arm down to a groove near the center of the record; at the moment of contact, the cantilever will briefly skew inward or outward; if it skews inward more antiskating should be applied.
It should also be noted that the amount of anti-skate needed can vary from record to record and even across the surface of a given record. So a general estimate is all that may be possible. And once that happy medium is found, it's very doubtful that even a careful listener will hear the difference from record to record.
@bpoletti , doubtful? Michael Fremer can:-) I have a Schroder tonearm so you know where my affections lay.
I am not sure where the 10% of VTF came from but It seems to be the consensus in the industry.
I use to use a test record with four increasing groove velocities. The consensus is that this overestimates antiskating but then wouldn't you want the antiskating set to track the most difficult passages? The issue is after all tracking or miss tracking. The lower velocities will track fine even if the anti skate is overestimated. It is nice to have a specific target number (even if it is just an averaged value) Makes me feel better.
@larryi , I really like your analogy with the arm. I think it is easier for people to understand than the water-skier analogy.
Can a tonearm be made that does not skate? Theoretically yes, in reality probably not. But, you certainly can make one that skates very little. The Reed 5T and Schroder LT are good examples. They have to be perfectly set up and the tonearm has to be dead level. Keeping everything perfect is an impossibility so, there is always going to be a small amount of skating...that only Michael Fremer can hear.
I also find the Reed T5 and Schroder LT approach interesting. Both arms are based on the Thales circle geometry and achieve close to perfect tangency and do so without an offset angle that creates skating force. At least theoretically, the Reed T5 is a touch more elegant because the movement of the arm pivot is achieve by using a laser sensor to detect loss of tangency and a motor to then rotate the arm base to move the pivot point, while the Schroder LT requires the arm to pull the base into a new position. Of course, the simplicity of the Schroder approach is a big plus for that design. If I were to change my arm (Vector 3), I would certainly consider both of these arms. About three years ago, I talked to a Reed representative at a show and found out about the bad news on the T-5--it costs something like $18k.
Saw the post from lewm from a while back. Yes lewm I do read what I write. The problem is not the writing. The problem is comprehending. Of which there is a lot of on this thread.
Skating forces are generated just like I said, by the stylus overhanging past the tangent. When the stylus is tangent then the force of dragging through the groove is in line with the arm pivot and there is no skating force pulling towards the center.
But all cartridges have over hang. That is why we call it overhang adjustment. Because of this overhang the stylus is always on the groove past the point of tangency. Because of this there is always a vector force towards the center. This is the skating force.
Now lewm, this is where you want to pay extra special attention. The cartridge can be mounted on the arm pointing any direction. It can be angled in, or out, or at right angles- or backwards for all that matters. As long as the stylus is always in the same overhang position then there will always be the same skating force.
Nothing to do with the cantilever. That is a whole different subject. This is where people screw other people up. Got to keep each thing straight.
Now that everyone understands skating force comes from overhang, it should be obvious Fremer is right. (Or at any rate what Mike says Fremer says is right.) Because the skating force comes from overhang, then the greater the drag on the stylus the greater the skating force.
This is why a blank record is no way to set anti-skate. A blank record has a lot less drag than a groove. A highly modulated groove has a lot more drag than a silent groove. Understand all this and it should be obvious there is no way to use VTF to calculate anti-skate, other than as a crude ballpark estimate.
Please guys, don't make this harder than it has to be!
One added point, I think has not addressed.
The OP is mentioning an Ortofon Quintet Black cartridge, yes?
This might play into the MC / Lewn discussion too.
For some interesting reason - when checking for the most suitable anti-skating force with this cartridge, running it on a test record with a non-groove (smooth) section, in about the middle of the normally grooved section, you will find that even by just skating on a smooth vinyl surface the t-arm, cartridge, cantilever, stylus assembly gets pulled toward the platter centre.
The way MC related, and why, as due to the geometry of gimbled t-arms.
So, a stylus running in a groove have nothing to do as such, in the skating force/pull matter, yes?
But the main point now: this particular cartridge using a Shibata stylus, for some reason, needs by comparison to other cartridges, a lot more anti-skating force to compensate the skating force/pull present.
On the SME V t-arm, the anti-skating dialable calibrated force is practically always pretty much equal to the vertical tracking force, as I many, msny times could confirm.
The Ortofon Quintet Black and incidentally also the Cadenza Black require quite some unusually more anti-skating force to ballance their skating pull action, when tracking at the optimal 2.3 gram VTF.
It seems to have to do with the stylus shape, being more pointed than many other styli - my best guess... and I might be wrong, it having to do more with the relatively high 2.3g VTF?
The anti-skating force dial almost needs to be set as high as 3 (g)! to balance the skating pull.
So, where does this fit into the MC/Lewn discussion?
Will the skating pull be less if the stylus runs in a record groove?
Somehow I do not think so, and why have different styli or a highish VTF different relative skating pull?
Just some unanswered question - and related to the OP Quintet Black.cartridge also.
His actual question clearly having been unequivocally answered: using zero anti-skating force, when performing cartridge alignment, an absolute given.
@millercarbon wrote Skating forces are generated just like I said, by the stylus overhanging past the tangent. When the stylus is tangent then the force of dragging through the groove is in line with the arm pivot and there is no skating force pulling towards the centre
MC, with a Origin Live tonearm and a properly mounted cartridge, the stylus is never in line with the arm’s pivot due to the head-shell offset. Simply impossible unless you mount the cartridge to mimic a zero offset tonearm.
Geeze Louise! The lengths some will go just to try and get a dig in!
Check this out- a line runs between two points. Just to help you out, we will call the points A, and B. Are you with me so far? Okay so we are gonna call the stylus Point A, and the Pivot we are gonna call Point B. Are you with me? Have I lost you? I bet I have, this is so hard. But it is only getting harder. Because sorry, but this is a story problem. You have the story. Now the question: Are A and B in a line? Of course they are. How can they not be? Anyone? Beuller?
What you mean to say is the stylus is not in line with the arm tube. But this is completely different and utterly irrelevant. The arm tube can be straight, or curved, and the headshell also can be in line, or offset.
These things make a difference, sure. BUT NOT TO SKATING!!! Please, please, PLEASE stop trying to confuse everyone by changing the subject!
@feldman4 I have too many MFSLs to check. But look for 45rpm classical symphonies presented on four discs and issued around 2005. Typically, each movement is presented on one side, so the other four sides are empty. Given the pricing effect, I don't know what is the advantage of doing that since the record needs to be pressed in just the same way, creating just the same conditions as in a disc modulated on both sides. Perhaps they felt there is advantage in never having to put the modulated side against the TT mat. They don't seem to do it now.
Or if you don't mind getting drawn in, you could phone them; they are very helpful.
@mijostyn Did you ever hear an Aeroarm? There are only about 4 loose in the whole world! If not, please pipe down and stay piped down.
Obviously a disc pressed off-centre is faulty (many of them I agree) and will not play to best advantage, but the lateral oscillation will be exactly the same when played with pivoted and parallel arms and will have precisely the same effect on the cantilever, located as it is very close to tangential to the groove. Surely that is simple enough.
And why do you say the anti-skating must be 10% of TF. As @justmetoo points out, the requirement will vary according to stylus profile.
@justmetoo The reason Shibata and Line Contact stylii need more anti-skating is that their extreme eliptical narrow profile lateral sides create more friction with the groove walls compared with, say, a spherical stylus, the other extreme. The contact area is far less so a like downforce creates more friction. Such stylii typically feature on moving coil cartridges and need to run at greater tracking forces, typically 2.5g or more compared with a MM that can go down below 1.0g.
But 2.3g of anti-skating is waaayyy too much. You are damaging your records and stylus as well as getting bad sound. @jmijostyn is overdogmatic like many here, but about on the money. Turn it back and listen for less distortion and better channel balance.
@mc When did you measure the friction in the groove and on an unmodulated side?
There is a very interesting method for setting anti-skating force on the website of Vacuum State Electronics. It was written by the late Allen Wright, a highly talented electronics designer and expert on all things analogue:
(for the advice on anti-skating, see page 2 of the document that opens)
Allen recommends using the music grooves of a normal record, not a blank disc. And he recommends identifying the correct anti-skating force by ear. His method is, I think, well worth following.
The central idea put forward by Allen is that adjusting for optimal anti-skating force involves proceeding by small increments - which at first may produce no audible effect (his advice is to concentrate your attention on the right channel, listening particularly for maximum microdynamics).
As one approaches the range of correct settings, there will suddenly be a very noticeable improvement in the right channel (in other words, anti-skating setting follows a very shallow curve and then suddenly switches to a very steep curve - see Allen’s representation of this in ‘Pix 3' on the webpage).
So, I wonder whether anyone has any comments on this, based on their experience.
There is a further interesting point that Allen makes: once you reach - by small increments - the point where the right channel is performing as well as the left channel, you can then go on and apply further small increments, and the effect will be to produce further improvement in both channels. If you then proceed beyond this point - with one increment too much - there will be a sudden audible worsening - a collapse of the microdynamics - in both channels. In other words, once you exceed the optimal anti-skating force, there is a sudden, precipitate fall-off in performance.
Does anybody’s experience of setting anti-skating force confirm Allen’s account?
Yes - I triangulate the three methods.
Step 1 - I use Soundsmith's technique of setting by dropping the stylus between the inner grooves in the run off and doing an initial set.
Step 2 - I then use the Allen Wright method, running up from low to high antiskate. There is a sweet spot where the sound is most natural.
Step 3 - I check the cantilever to make sure it is straight. You can also use an eccentric record to check if the cantilever shifts more to one side than the other.
Allen Wrights methodology is much easier to perform if the VTA is dialled in accurately, because that with the correct antiskate gives you maximum ease and naturalness of sound, the most harmonically complete.
Using rules like x% of tracking force is wrong because you dont know the compliance in the horizontal plain, it can be quite different to the vertical compliance specified.
Clearthinker, will an airplane fly without wings? No, I do not have to hear one. All I have to do is look at it. Every tonearm must deal with the laws of physics even if you do not understand them. Bow Wow. (dog barking). I think you might want to consider changing your user name. I'll change mine to "dogmatic"
@justmetoo, friction is much lower in the record groove than it is on a blank record. This is counter intuitive but lets see if I can explain it so it makes sense. The major determinant of friction in a record groove is VTF. Next is the surface area contact. The greater the surface contact the lower the friction. What will have greater friction, the point of a knife or a marble.
In the groove the stylus has two contact points and distributes the VTF between the two. On the surface of a blank disc there is only one contact point and the full VTF bears on it, the point of a knife. At the same VTF line contact styli will have less friction than elliptical styli. This is why line contact styli can get away with higher VTFs without increasing record wear. Yes, modulation plays a role but minor in comparison to contact pressure. In the groove the contact pressure is 1/2 that on a blank disc.
Dear Mijo, The friction force is independent of surface area. The formula is f = uN, where f is the friction force, u (Greek letter "mu") is the coefficient of friction between the two bodies in contact and varies according to the materials of which they are made, and N is the "normal force", which is the force by which the two bodies are pushed against each other, in this case gravity. However, I do agree with you that a groove-less LP does not mimic the actual skating force generated when one plays a record.
MC, In your efforts to be flippant, to pretend everything in the world is simple and that you uniquely understand the simplicity, and to belittle others, you are truly annoying even me, who doesn't give a rat's patootie. I could refute your refutations of stuff I wrote, but I won't bother. Suffice to say, it is not that you are wrong but that you are always half right, yet you claim to be completely right.
mijostyn"friction is much lower in the record groove than it is on a blank record. This is counter intuitive but lets see if I can explain it so it makes sense. The major determinant of friction in a record groove is VTF. Next is the surface area contact."
This is not at all accurate, correct, or true you have a profound, distinct, extreme lack of knowledge and understanding of very basic, elementary, introductory physics.
I don't want to get into whether friction is higher or lower on a blank record vs. in the groove--there are too many variable to consider. For one thing, I have not seen mention of the fact that, when playing a modulated groove, the stylus is being dragged at a MUCH greater velocity (the path of a modulated groove is much longer per inch of record circumference) and there is inertia of the stylus moving side to side to consider as well.
None of this matters as to whether Ledermann's approach of using the blank side of a record is valid. He acknowledges that this does NOT duplicate actual playing conditions, but, his experience has shown that it results in a decent proxy for a correct setting. He has a lot of experience with examining stylus wear so he knows a thing or two about what achieves even wear.
@lewm, N is not necessarily gravity. It is the force applied perpendicular to "ground" which is not necessarily horizontal to the earth's surface. You are right, there is no unit of surface in the equation and I am not sure what the work around is but it is probably going to be a change in "u."
The same force on a knife tip is going to generate more friction than the same force on a marble. "u" for the knife tip is going to be much higher than "u" for the marble. Whatever.
@larryi@, all this agrees with Frank Schroder's approach (which Peter Ledermann adopted) Letting the arm drift slowly inward on a blank area is going to require less anti skating force than holding it still because friction in the groove is lower than friction on the blank surface.
Although a larger area of contact between two surfaces would create a larger source of frictional forces, it also reduces the pressure between the two surfaces for a given force holding them together. Since pressure equals force divided by the area of contact, it works out that the increase in friction generating area is exactly offset by the reduction in pressure; the resulting frictional forces, then, are dependent only on the frictional coefficient of the materials and the force holding them together
@minostyn Dogmatic is when you opine on sound without hearing. Even Miller knows that.
I suppose you choose your equipment without listening to it. The dealer's dream, but you should buy mail-order.
You're sure cleverer than I; you can tell how it sounds by just looking. I always like to audition. Anyone else here buy without listening??
Go to ZuAudio and follow their procedures and you will be amazed I know I was and I'm going on 76 and have finally learned how to set up an arm to Perfection. In all my time this company is the only one that nails it as most will try to get you to buy expensive Crap don't fall for that. All you need is a blank Record that costs 30 bucks.The so called Gurus are mostly from what I've found are flat out Wrong. ZuAudio makes a souped up Denon 103 which has been my favorite since the 80's. It also was the late Great Art Dudley's favorite also.
The best way to set up is use the advice from ZuAudio as I have been into Audio Since the 60's. They have info on their site and I have to tell you it really works great. I was fed misinformation for a long time but this company nails it the improvement is astounding. For Anti Skate you first must get a blank record around 30 bucks. after you do all the recommended procedures set the arm in the middle of where your grooves would be and when it neither goes in or out you will have perfect alignment and also of great importance is getting your Vertical Tracking Alignment as to make it Orthogonally correct.
@lewm, I discussed the problem with my brother the mad scientist (MIT PhD) When you play a blank record the stylus leaves a visible scratch mark in it's path. The pressure on the very tip of the stylus is so high that it is actually digging into the vinyl so the friction equation no longer applies. It would be more appropriate to call it "drag" on the stylus which would have to be measured in order to compare it to the frictional pull on the stylus under normal conditions. The "drag" on the stylus is obviously higher since it requires more antiskating force to hold the tonearm steady.
My pal had a Grace badged Rega Planar 2, a Grace F9, and a Grace 747 arm. In the info he had, Grace said to look at the cantilever as the record plays, then to adjust the anti-skate to make the cantilever stay as straight as possible. This makes perfect sense, and allows for different settings for records, with varying amounts of info to be fine tuned. I tries it on his Grace and my two arms, and it does work out very well.
MC, Yes, if you can draw a straight line from stylus tip, through the cantilever, that intersects the pivot point, then you have zero skating force. And to Larry, yes the reason conventional pivoted tonearms that are mounted so the stylus overhangs the pivot and which incorporate an offset headshell NEVER exhibit zero skating force is because, even at either of the two null points (where the cantilever IS tangent to the groove walls), the offset headshell alone creates a skating force. But no, MC, not every pivoted tonearm exhibits a skating force at all times. Underhung tonearms, of which there are only a few, that have zero headshell offset, will give only one null point on the surface of an LP, but at that one null point, the skating force is momentarily absent, because the tonearm meets the criterion stated in my first sentence. (Pivoted tonearms that incorporate complicated mechanisms for maintaining tangency to the groove at all times are not part of this discussion.)
Mijo, "mu", the coefficient of friction is non-negotiable and is not dependent in any way upon surface area. Testpilot got it right. It is a constant for any two materials. There are tables showing coefficient of friction for a wide variety of material pairs. Someone else mentioned velocity. No, friction force is not dependent upon velocity, either. Also, can you say where you got the idea that a stylus tip gouges a grooveless LP? Before you go quoting the "tremendous" pressure of a stylus tip on vinyl, which is arrived at by extrapolating the teeny-tiny surface area of a stylus tip to a square inch and multiplying the VTF accordingly, I doubt the validity of making that extrapolation. But I am open to contrary evidence that I might be wrong.
In my opinion, the reason that running the stylus on a grooveless LP does not mimic the skating force generated while playing music is that in the process of negotiating the tortuous groove, the stylus tip is constantly subjected to acceleration and deceleration (acceleration = change in stylus velocity, as someone else mentioned; deceleration = negative acceleration). Each tiny acceleration requires a Force (F = ma), because the stylus tip has mass, pulling the stylus in the same direction as that of friction. That force is adding to the friction force in a way that does not happen when there are no grooves and no music.
lewm- MC, Yes, if you can draw a straight line from stylus tip, through the cantilever, that intersects the pivot point, then you have zero skating force.
No. Wrong. That is not it. It's overhang. Last chance. Not gonna keep repeating. Explained perfectly clear already. Skating forces come from overhang. Period.
There's videos where Michael Fremer says this exact same thing: skating force is caused by overhang. No overhang, no skating. Nothing to do with the stylus, cantilever, or anything else. Michael Freaking Fremer! But then he tends to address an audience of people who want to listen and learn.
Well I have tried my best lewm. You have the info. Everyone has the info. What you do with it is up to you. Choose wisely.
Stylus overhang, along with headshell offset angle, was posited (by Baewald and Lofgren back in the early 40s, probably) in order to make it possible for there to be two null points on the playing surface of an LP. "No overhang, no skating" is flat wrong. An underhung tonearm with zero headshell offset does generate skating force everywhere on the surface of an LP, except at the single null point. Why do you insist upon your too simple explanations of nearly everything?
You were correct to fault me for my sentence: "Yes, if you can draw a straight line from stylus tip, through the cantilever, that intersects the pivot point, then you have zero skating force." Because I neglected to say that at the condition described the cantilever must be tangent to the groove. THEN you have zero skating force. That's a description of an underhung tonearm with zero headshell offset angle at its single null point on an LP. MF is not at all my guru when it comes to the physics of playing an LP. He is often parroting something he was told and is sometimes wrong. In this case, he was being too simple, like you.