Is my anti-skating too strong.

Tswisla

look at the second post that MC wrote and you will have your answer.

Im with Ozzie on this one.  I track my Ortofon a hair heavier just for security, but it sounds better without a/s to me.

Can someone please confirm or correct my thinking.  If I occasionally hear distortion in the left channel on peaks, my anti-skate is set too high (too much force to the outside of the record).  I need to decrease the anti-skate to allow more force in the inside of the groove.  Is this correct?  I currently have it set to the same level as my tracking force.  Thank you.

@no_regrets, if the anti skating is off the distortion will occur in one channel or the other. If it is set too low the right channel will distort, too high and the left channel will distort. Having said this orchestral crescendos always occur at the end where the modulation is tightly packed and tracking error and it's significance increases fast. If the cartridge is not positioned correctly you can get distortion here. The cartridge may just be miss tracking because it is a poor performer or worn. It could be the record is damaged from play with a worn stylus. 

Inner grooves are the hardest part of the record for a cartridge to track because the groove modulations (wiggles) are compressed into a smaller diameter and become more extreme in shape.  Wrong antiskating can contribute to problems with tracking, so in that sense you could say they "cause" the problem.  When grooves are highly modulated more skating force is developed, and therefore, more antiskating would be desirable.  But, as Peter Ledermann points out, increasing antiskating to optimize high modulation playing would mean that, for the vast majority of the time (when modulation levels are lower), antiskating is set too high.  That is why he discourages using test records to set antiskating for equal distortion in both channels at high modulation levels.

@jjss49   Thank you for posting the link to Peter's videos on AS. He seems like a really great guy and I think he did a great job with the videos.  I certainly am not an expert on this topic but what he was saying seems to make sense to me.

A question for all.... I had read on another thread that a person was experiencing distortion in highly modulated grooves towards the very end of the record.  I am wondering if that is a result of not enough Antiskating, or is it possibly just groove damage, or a misalignment of sorts?  He said it doesn't happen all the time but only on highly dynamic and modulated passages near the end of the record.  The rest of the record was fine.

Any thoughts on that?

@lewm , all bark, no bite it seems.

Yeah, please do enlighten the rest of us.  I am sure that anyone with a moniker that incorporates the word "skating", sans vowels and a "g", is expert.

@sktn77a , please, inform us! What is BS and what is not? 

Sheesh, amazing how much uninformed BS in this thread!  I won't even dignify some of the posts with a response.  But I will advise readers to look elsewhere for information on antiskating, its causes, and remediation.

@lewm , I am not arguing about the coefficient of friction. That would be silly. However, play a blank record then have a look at it under the light. Then talk to me. If you do not have a blank record The Lumineers Cleopatra has a blank third side. 

mijostynAbsolutely. The more tools we have in our toolbox the better.
 I don’t have a Wallyskater. I have looked at them but have not purchased one yet. At the moment I’m have difficulty visualizing how you setup your digital stylus gauge. I’ll relook at your other post.
joe

@joenies,@joenies, you missed one! Direct measurement either with a WallySkater or something like my Gizmo and your digital stylus gauge.

@larryi , The LT is much less expensive, $8K to $10K depending on where you get it from and which version you get. I would get it directly from one of Frank's dealers in Europe. Yes, the Reed is very expensive and complicated. The Schroder does exactly the same thing but in a much more elegant fashion. 
There are other factors than just the quality of the bass. No record is perfectly flat or concentric. With high horizontal effective mass the cantilever reacts before the arm, remember the cantilever and stylus have to pull the arm along, then the arm gets going and continues on taking the cantilever and stylus along with it and you get this low frequency oscillation which causes a lot of distortion. I have watched several air bearing arms and Clearaudio arms and you can usually see it happening. The same problem occurs with arms that have a high polar moment of inertia. This is the rational for limiting mass at the end of the arm and is why SME changed their approach to tonearm design with the model V and all the best arms followed suite avoiding removable head shells and unnecessary mass out there. I hate to say this but removable head shells are for lazy people. Some designs like the Kuzma and the method Schroder uses are tolerable. The Kuzma looks bulky but the alloy is very light. He is trying to maintain stiffness and may be going a little overboard. The Schroder design looks sort of flimsy but it is not. The cartridge locks in solidly.  I have a new Schroder CB which is waiting for it's turntable. I think if you are a cartridge jockey multiple arms or tables is a better solution than removable head shells of the old SME type that the Japanese are so fond of. Most of us install a cartridge and leave it be for years. I have multiple cartridges but there is always one I like best and that is the one that stays in the arm. The others just sit in a draw. I sold a bunch of them. I decided I'd rather collect records.    

Thanks to everyone that helped educate this forum on the math and physics related to anti-skate. Hopefully we can all agree anti-skate exists. Question is how is the best way to set it. Not sure there is a best way.
 I use the following methods.
1. Use a blank test album. This will get you into the ballpark. Problem with this method is you can only use the blank portion of the disc 1 maybe 2 times, do to micro grooves forming.
2. Use a test album with a modulated signal, adjust as needed.
3. Play an album and look at how your cartridge is tracking.
4. Listen to music and try to trust your ears.
If you have test equipment, oscilloscope, distortion meter and other equipment there are a few test albums out there you can use.
Again thanks to all for the education.
joe

The method of using an entire unmodulated side of a record is akin to aligning a vehicle using a perfectly flat road, (good luck with that).  There are dynamics involved in all 3 dimensions.
The starting point would best be the test record and then by musical records.  It will change from record to record but it would be unreasonable to "test" and catalog each one for adjustment.

Hello UDOG.  As you may have guessed by now, there is some controversy about anti-skate force! I did not read all the responses, but they quickly deteriorated into petty squabbling and personal put downs. I am sorry for that nonsense. The term "anti-skate" gives you a clue. The arm is being pushed toward the center of the record by the spiral nature of the groove. Let's pretend the record is smooth as ice; if we push a skater, he/she continues to move even after we stop pushing. The skater coasts forward with only the friction of the skate upon the ice to slow that motion. The spiral groove pushes the mass of the arm and cartridge constantly and the arm "coasts" as well. So there is a force pushing against the inner wall of the groove - the "skating" force. The pitch of the groove varies, sad fact, so adjusting instant by instant to balance the skating force with the force of the outer groove wall against the stylus is not possible, but we can shoot for an average. Record playing is an expensive process and we want to minimize the wear and tear on the record groove and the stylus. Here's how to make the adjustment. (The blank groove record is a great idea!) Put the arm over the record about halfway across, the cueing arm holding it just above the record's surface. Notice the position of the cantilever with relation to the front of the cartridge. It should look centered. Now lower the stylus into the groove. The arm was not moving and the groove will accelerate it toward the spindle. Notice the cantilever's movement and recovery. Count to five, giving time for the acceleration to occur, and note the position of the cantilever. Is it still centered? So you can see this process in action, put the "anti-skate" setting at either extreme and watch what happens. You want to set the 'anti-skate' control so that the cantilever stays centered while the record plays. A set of close-up reading glasses from the drug store may help. Get the cheap ones with the wire frames. Keep Smiling!

mijostyn,

I agree that if horizontal mass is high enough, it raises concern with very low frequency resonance.  I was just pointing out what is the theory behind the anisotropic arms.  As long as the bass frequencies are above the low frequency resonant point, those arms should work as intended, at least in theory.  The theory also only works if the bass is mastered in mono so there is no vertical modulation for those frequencies.  Some mastering engineers say they do blend bass to mono, but, others say they do not.  

What is your personal experience with either the Schroder LT or the Reed arm?  Do you know how much the LT costs?  I once inquired about the Reed, but, I lost interest when I found out it cost about $18,000 (two and a half years ago).  I am assuming the LT is not cheap; my friend's Schroder arm was quite expensive (but exquisitely constructed).

Here's my take on a/s.   I have a VPI 10 with 2nd pivot/Winfield cartridge.   I was very careful to dial in the a/s using various methods, but got a compromise that I thought was good.  A few days ago, I got a couple of Schumann resonators which really opened up my system.   Now, I hear a resonance with the a/s set that disappeared when I removed the a/s altogether.  The clarity certainly improved.  It may be VPI's means to apply force...weight with articulated arm attached to the arm tube with a string. 

@larryi , high horizontal effective mass does not mean the cartridge does not move. It means it resonates at a lower frequency. The penalty for that is the same as it is for any pivoted arm and remember on the other side of this equation you have the much lighter vertical effective mass which is going to do exactly the opposite in the vertical direction destroying the bass and even causing feedback under certain circumstances. You can not separate the two. You are caught between a rock and a hard place.
@lewm , and that is the problem with the argument with a high effective mass being "OK"  On top of that the slow oscillation of the cantilever at the resonance point is going to place the cantilever in a less linear point in it's travel increasing distortion and tracking problems. The market usually figures things out. No air bearing arm has ever gained traction in the market and I do not think it is because of the complexity of having a compressor. The Clearaudio straight line trackers are lighter but still cursed by the same problem on top of hygiene issues and people in general do not care for them. No compressor.
I also object to your coloring this as my "ideology." It is not my ideology any more than the sun rising in the east. You can hypothesize that this issue does not cause a sonic problem but the issue exists. 
Finally, IMHO a good pivoted tonearm is going to function and sound better. If tangential tracking is your thing check out the Reed 5T and the Schroder LT. The Schroder in particular is genius. It accomplishes the goal of tangential tracking while maintaining similar vertical and horizontal effective mass and avoids the use of motors and compressors. 

@lewm
I’m not an advocate either way, I always base my views on specific cartridge/arm combinations that I have experienced, not speculation..

However, regarding high horizontal effective mass, the most interesting experience I have had is that my Shure V15vxmr & Shure V15vmr sound superb in both the Dynavector and the ET2, despite their high horizontal effective mass and high compliance. This is counterintuitive.

As stated above I left the Shure V15vmr on the ET2 for 10 years, stabiliser brush removed, and the cantilever was still dead straight after all that time. I actually sold the Shure for more than I paid for it, and the purchaser viewed the 10 year old stylus through a mircoscope and was very happy with it - dead straight and little wear..

Split Resonance - there are several arms that do this is various ways
Eminent Technology, Dynavector, Moersch we have discussed.

Other examples are Helius & Vertere where the effective length is different in the horizontal and vertical plains.

Bruce Thigpen, who majored in physics, audio engineering & air bearing design argues that splitting the fundamental resonance results in more accurate phase response across the spectrum. Geoffrey Owen of Helius subsrcibes to this view as well. Dynavectors argument is based on bass accuracy, providing a more stable platform for the bass notes as cut into the groove.

Regarding snapped cantilevers and linear tracking arms - Kuzma & Walker have far far higher effective mass than the ET2. Those arms I think are too heavy. Mechanical trackers are not great on cartridges either. 

lewm,

You are describing the Moerch anisotropic arm I described above.  I think the model is the DP8 or DP9.  

I have no idea if 25 gms is too high, I just know it is WAY higher than is common with conventional arms.  In the past, some users of air bearing arms reported snapping the cantilevers on their cartridges (Walker owners, I believe), but, who knows whether there is some other cause for such problems (its not like user error is a rare phenomenon).

So, the discussion has come around to the idea that high effective mass in the horizontal plane, relative to vertical effective mass, is at least theoretically a good idea.  How does one know that 25g is too high?  What is the typical horizontal compliance of most cartridges?  While reading the preceding posts, I remembered that some pivoted tonearms place outboard weights right at the pivot point, extending out on either side at a 90 degree angle to the arm wand.  These weights are added in order to increase horizontal effective mass, and I have read at least one thread, a few years ago, wherein the benefits were said to be evident.  M Fremer has popularized the idea that horizontal mass should not be so high, for what that is worth. It seems logical to me that when the stylus is trying to trace the heavy horizontal modulations of a bass response, you want the stylus/cantilever to move whilst the arm stays as still as possible. 

Horizontal effective mass is 25-35 gm and vertical is 7 gm. A normal pivoted arm might be 12 gm vertical and 13 gm horizontal. 20 gms is much to wide a divergence.

You miss the point I made earlier - the effect of splitting the horizontal and vertical effective mass is an advantage - vastly reduces the fundamental peak resonance in amplitude. In a conventional arm the vertical/horizontal resonance are the same and the peak amplitude from the fundamental resonance is cumulative.  By splitting the horizontal and vertical effective masses you have 2 fundamental resonance peak amplitudes that are not cumulative becuase they occur at different frequencies. Whilst the fundamental resonance may be out of the audioband for most systems, If you look at the Shure white papers, the fundamental resonance can be devastating to accurate tracking and distortion and has significant artifacts within the audio band. 

Tracking error is not near as much of a problem as it is made out to be not that minimizing it is not a good thing.

Really - check out how many folk have offset/bent cantilevers within a short period of time - its well north of 50%.

It is NOT ideal to have the cartridge moving.  You want the cartridge position to not change so that the full motion of the needle swinging side to side is transferred to the generating element of the cartridge.  If the cartridge moves, the amplitude of the signal reaching the generating element is reduced.  That is why high effective mass (high inertial mass) reduces the tendency of the cartridge to move in response to large bass modulations.  

Moerch  makes an "anisotropic" tonearm with large outboard counterweights located at the vertical pivot.  Because of this location, the weights contribute little to vertical mass, but, they increase horizontal mass for the purpose of improving bass response.  I've heard this arm and it does have a bigger bottom end than typical arms.  I also thought the bottom end of air bearing arms seem particularly full, but, I have no way of attributing this to the high mass.

I personally agree with you that excessive horizontal mass is quite undesirable.  This probably puts a strain on the cantilever/suspension of the cartridge and might even cause uneven stylus and groove wear.  I have never heard the Shroeder LT or the Reed T-5 arm, but, I really do like the engineering concept behind those arms.  They seem to be the best way to maintain proper azimuth without causing other problems.

A high effective horizontal mass means that the arm will not swing side to side from the needle tracking the wide modulation of the groove (the full groove swing will be translated to movement of the cantilever instead of some of the movement lost to the movement of the arm).

Perhaps you could explain why it is imperative to have the cartrdge swinging around whilst trying to measure the groove. Have you ever tried to accurately measure the height of your ceiling whilst jumping up and down on a trampoline - you can't. 

An effective mass of 25 gms is very high.  Whether or not this translates to a real problem is another matter.  As lewn notes, some arms deliberately have a higher horizontal mass to improve bass response, but, it is usually not that high.  Bass notes are often cut monophonically because cutting bass stereophonically would mean excessive changes in the depth of the groove.  A high effective horizontal mass means that the arm will not swing side to side from the needle tracking the wide modulation of the groove (the full groove swing will be translated to movement of the cantilever instead of some of the movement lost to the movement of the arm).

Just to point out that there is a good argument to be made in favor of a high horizontal effective mass for producing accurate base response. I am not coming down either way on this subject, but certainly there is a school of thought that is contrary to mijostyn’s  ideology.

@dover , and there you have it dover. Horizontal effective mass is 25-35 gm and vertical is 7 gm. A normal pivoted arm might be 12 gm vertical and 13 gm horizontal. 20 gms is much to wide a divergence. Your use of terminology is a bit odd. I am looking at a picture of the ET2 as I type. The counterweight is very much a portion of the arm's effective mass. ANYTHING that moves with the arm is part of it's effective mass. In no way shape or form is the counterweight "decoupled" in this manner. 
Over the years many companies have tried to pull this one off thinking that somehow they could get around the laws of physics the last being Frank Kuzma. It should be no great surprise that people resoundingly like his brilliant 4 Point arms better. The fact is it can not be done, at least not that way. They are all destined to failure just like the ET 2. Straight trackers with a motorized carriage carrying a more typical pivoted arm might be able to do it if it were not for the difficulty in overcoming the noise and vibration of such a drive. Reed and Schroder have it right. 
Ditch the ET 2 or use it as an antenna or coat rack or something and get yourself a Schroder LT. You will be much happier and people will think you are a clever guy. It is good that you realize a cartridge has to be chosen to work correctly in a tonearm, that they have to be matched. There is no match for tonearms like the ET 2, none. There are only compromises., compromises you do not have to make with other arms.
Tracking error is not near as much of a problem as it is made out to be not that minimizing it is not a good thing. But, the price you pay with air bearing arms is just too high. 

@mijostyn

you can not uncouple effective mass. If it is attached to the tonearm the tonearm must move it.

I said the ET2 has a counterweight that is decoupled in the horizontal plain, I did not say "the effective mass" is decoupled.

Now looking at your air bearing arm, the vertical effective mass is quite similar to a pivoted arm.

If the arm weights 150 gm then the effective mass in the horizontal direction is 150 gm. If a pivoted arm weights 150 grams the effective mass would only be perhaps 20 gm.

Your comments on the effective mass of the ET2 are way off base. What you fail to understand is that the total mass of the ET2 armtube, bearing spindle, counterweight beam & weight are substantially less than most conventional pivoted arms - 25-35g in total.

The specifications for effective mass for the Eminent Technology ET2
are as follows -
Horizontal effective mass - 25-35g
Vertical effective mass - 7g

Furthermore on my own ET2 I have a non standard armtube that reduces the horizontal effective mass by another 5g.

I also have modified the decoupling of the counterweight, The standard ET2 uses a leaf spring. I use a teflon V block/knife edge arrangement which allows the cantilevered counterweight to swing freely in the horizontal plain. The V block can be tightened with an allen screw - this allows me to tune the "level of decoupling" to the individual cartridge.

You can add viscous damping but then you increase the work required for the record to move the arm and you increase record wear. This is the problem the Reed 5T and the Schroder LT are

I agree with this - I dont like viscous damping.
However, I have implemented electromagnetic damping on the arm in the horizontal plain which electrically only engages when the bearing spindle is moving sufficiently, specifically eccentric records, to proprotionately dampen the back and forth motion. Interestingly the volume increases with the electromagnetic damping implemented, so the electromagnetic damping is helping the cartridge, not hindering. The Dynavector tonearms also use electromagnetic damping in the horizontal plain.

FYI I also have pivoted arms in use - FR64S/Naim Aro/Dynavector 501 {rebuilt to Baerwald}.

Are there better arms - sure - but as I stated above there is "no best arm" - I personally find cartridge and arm matching and quality of set up as important as the quality of the arm and cartridge to the end result, perhaps even more so. A poorly set up turntable/arm/cartridge, no matter how expensive, is fundamentally destructive to the music.

Excellent Lewm. Nothing to add to that explanation.

@dover , I looked into it and you are right about the Eminent Tech vs Walker. I had always assumed Walker was first. Assumptions are the mother of all f--- ups. Thank you for correcting me.

However, you can not uncouple effective mass. If it is attached to the tonearm the tonearm must move it. You can change it's resonance characteristics but you can not write it off as mass. A tonearm must move in two directions and only in two directions, vertically and horizontally. Pivoted arms have about the same distribution of mass in both directions. There is usually a little more horizontal mass in the form of the bearing housing which is good it breaks up the resonance peak a little so with a specific cartridge the horizontal resonance point might be 8 Hz and the vertical 10 Hz. Now looking at your air bearing arm, the vertical effective mass is quite similar to a pivoted arm. Most of the mass is at the axis of the vertical pivot which means it contributes very little to the effective mass. The more the a mass is out by the cartridge the more it contributes to the effective mass. The cartridge is literally one to one. If it weights 10 grams then 10 grams is added to the effective mass. If one were to mount the cartridge at the vertical pivot (a bit weird but for the sake of argument) it would only add perhaps one gram to the effective mass. In the horizontal direction we now run in to the big problem. The entire tonearm has to move the same distance. A mass at the back of the arm contributes 1 to1 to the effective mass. If the arm weights 150 gm then the effective mass in the horizontal direction is 150 gm. If a pivoted arm weights 150 grams the effective mass would only be perhaps 20 gm. So now with the same cartridge whose vertical resonance was around 9 Hz it's horizontal resonance is 2 Hz or worse. You can see the oscillation on an oscilloscope. With a higher compliance cartridge you can frequently see it with the naked eye. You are depending on the stylus/cantilever/cartridge to move the arm. Anything that aggravates that resonance point will start the cantilever oscillating side to side. You can add viscous damping but then you increase the work required for the record to move the arm and you increase record wear. This is the problem the Reed 5T and the Schroder LT are circumnavigating. Very successfully I might add. This makes them hallmark products I believe as they dispose of tracking error but still interface with the cartridge correctly. 

but let’s check in with the OP, did anyone here help you ????????

MC listen before he buys ? surely, you must be joking...Mr. F ( who would have no trouble with the math, nor the egotist )

lewm-

MC, It's a matter of vector algebra, adding the various force vectors results in a net side force that can only pull the stylus toward the spindle

 
Finally. Took long enough. Thank you. 

MC, It's a matter of vector algebra, adding the various force vectors results in a net side force that can only pull the stylus toward the spindle (in the case of an overhung tonearm), because the stiffness of the arm wand prevents movement in the actual direction of the major net force, which is toward an ever-moving point that is always pointed to the rear but to the inside of the pivot (with a pivoted, overhung tonearm).  With an underhung tonearm, the direction of the side force actually changes from pulling the tonearm inward to pushing it outward, after the stylus passes through its single null point, where there momentarily is zero skating force.
"Each and every point on a circle is the same distance from the center. Therefore the vector pointing towards the center is zero."  It's not that the two statements are wrong.  It is that the two statements have nothing to do with each other.  Moreover, an LP groove is actually spiraling toward the spindle or the label, so each and every point is NOT the same distance from the center.  And there is a net vector force toward the spindle; we call it the skating force. (I know we agree on that, but you seem to lose sight of it once in a while.)

The ball on a string goes off into space on a straight line tangent to its circular orbit, when you let go, because you were applying a force that kept it circling, until you let go of the string.  That is called a centripetal force.  Because as Newton tells us, "every object persists in its state of rest or uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it".  
You wrote, "The motion of each point on the circle breaks down into a vector that is pointed straight ahead, ie tangentially, and straight towards the center. Each and every point on a circle is the same distance from the center. Therefore the vector pointing towards the center is zero."  What?

The reason why overhung tonearms can never have zero skating force can be shown by the Pythagorean Theorem.  As you say, tangency to the groove is what we are talking about, but we need tangency to the groove where the friction force generated at the stylus tip has a vector that passes back through the pivot point. Then and only then do we have zero skating force. Consider an underhung tonearm with no headshell offset angle that can achieve zero skating force at its single null point.  In that one moment, the distance from the pivot through the tonearm/cartridge is one side of a right angle triangle (side a).  The distance from the stylus tip to the spindle is another side of a right angle triangle (side b).  And the pivot to spindle distance would be the hypotenuse of the right angle triangle, side c.  Pythagorus told us that for any right angle triangle, c-squared = a-squared + b-squared.  But if you have an overhung stylus, side a (tonearm effective length) is always larger than side c (P2S).  So you can never achieve even a null point, let alone zero skating force, with an overhung tonearm, UNLESS you invoke a headshell offset angle.  The founding fathers of cartridge alignment handed down to us a headshell offset angle, so as to achieve two null points across the surface of an LP.  But they didn't give us any condition that satisfies what we need for zero skating force, because headshell offset per se causes a skating force.

Cognitive Dissonance... to say it again. 

No logical, rational argument will overcome it, as it locks one into ones belief system. 

MC, what we have here is just that now. 
So how to overcome Cognitive Dissonance? 

By telling the opposing party(ies) a good joke or tell them you love them! 🥰... i.e. to stop make those opposing feel defensive!

This, despite their stubborn opposition to logic, rationality, physics, geometry, newtons law, et al. Die using diverting arguments to obfuscate the issue at hand. 

Then maybe, just maybe, the opposing positions will be actually prepared to hear you, and stop 'sand-bagging'. 

Psychology is needed to let rationality come through! 
It's the human condition - not taught during 101 Physics, Geometry and Maths. 😏

BTW, it also seems so many folk were *seriously* at odds with Newton at his time! (Must have known too few good jokes?) 😝 

Michélle 🇿🇦 

@millercarbon could you post a link to any article that supports or further explains your skating force theory.

It's not a theory. It is physics. It is so obvious that Michael Fremer throws it out there as an off hand comment. I can explain it faster than I can find his 2 second sound bite in his 90 min video. So you go find it yourself if it is so important to you.

Here's the physics:

Draw a circle. Draw it nice and big, this will help for later. Put a dot in the center. That's your spindle. Now draw another point anywhere outside the circle. That's your tone arm pivot point. Now take a compass, or a stick, ruler- anything nice and straight- and set it up to go from the pivot point to anywhere, but let's stick with roughly an inch, beyond the spindle. This is your overhang.  

Now keeping the compass on the pivot point, swing it around across the platter until you get to the outside edge of the circle. Are you with me? Okay.  

Now go to the point where the compass is on the outer edge of the circle and very carefully draw a line parallel, that is tangential, to that point on the circle. Got it?  

Okay. That was all geometry. Now here comes the physics. The circle/platter is rotating. Rotational motion breaks down into vectors. The motion of each point on the circle breaks down into a vector that is pointed straight ahead, ie tangentially, and straight towards the center. Each and every point on a circle is the same distance from the center. Therefore the vector pointing towards the center is zero. The motion is entirely tangential.  

There are other forces involved but this right here explains why it is that if you spin a ball on a string and let go the string, the ball does not spiral off it goes in a straight line. So your straight line tangential to the circle is the only vector, and this means at this precise point where the stylus is the groove is moving in a perfectly straight line. A line that is infinitely short, to be sure, but straight nonetheless. (And this is why Newton invented the calculus, but never mind.)

So now look at your drawing. Notice anything? You did draw it I hope. No cheating! You asked me to explain, I'm explaining. Draw the damn thing!!!

What do you see? What I see is a straight line coming from the pivot point to the stylus, and another straight line tangential to the circle, and they cross at the point of tangency. They cross. They are not parallel. Are they? No. They are not. If they were parallel there would be no skating force. They are not. Which way is the tangent line headed? Slightly away from the spindle? No. Slightly towards the spindle? Yes. Draw an arrow on it. There is your skating force.  

What happens with overhang is the spinning platter exerts a large force pulling straight away from the pivot point, and also another smaller force pulling the stylus ever so slightly to the left towards the spindle. This is your skating force.

You can change the shape of the arm. You can change the offset. You can align the cartridge any old way you want. As long as there is overhang the inward vector will be there and that is your skating force.

Air bearing linear tracking arms can be made to have reasonably low moving mass, but, they lack the mechanical advantage of a fulcrum and pivot of a conventional arm, meaning that for any given effective mass, they do impose a lot more force on the cantilever to drag the arm to a new position than a conventional arm imposes in order to swing the arm around the pivot point.  This is an issue even if friction is zero.

This is not the case with linear arms that employ a conventional pivot and a sensor that detects when the arm is out of linear position and then turns on a motor to move the entire arm assembly.  But, as with every design, the motorized arm version has its own shortfalls, such as, vibration from the mechanism getting into the arm, lack of overall rigidity and mechanical grounding of tonearm vibrations).

The very short arm on some linear trackers (e.g., the ClearAudio arm), may give rise to another problem--a change in record thickness would mean a bigger change in VTA with a short arm than a longer arm.

The Schroeder LT is not a tonearm on a string design (I've helped set up and listened to a Schroeder arm-on-a-string and it is a good arm).  It has conventional pivots, but also an innovative mechanism that moves the arm, including the pivot point, in a semi-circle to greatly reduce deviation from perfect tangency while not causing skating forces.  Because it is using the drag of the arm tracking the groove to move the pivot, I don't know if it increases friction seen by the arm.  The Reed T-5 uses a sensor to operate a motor to move the base of the arm to achieve the same kind of result as the Schroeder.  

The bottom line is every type of arm has its pluses and minuses, and I haven't heard any type that I thought was obviously superior to another.  

It is so nice to be popular. I draw the English majors like a magnet. Must be my crappy punctuation. If it were not for spell check I would be the laughing stock of this site.

Birds of a feather:-)

Thank you Dover.  Finally someone who understands the principles and issues attaching to different arm designs.

Horizontal effective mass of a parallel tracker can inherently be much less than a pivoted arm.  Many parallel designs have arm tubes that mimic a pivoted arm because designers lack imagination and do not start with a clean sheet.  The stylus need only be two or three inches from the sliding bearer.  See Simon Yorke Aeroarm.
Dover, please note Aeroarm has adjustable VTA on the fly.

Yes, motorised carriages are nonsense.  They cannot constitute a low-friction bearing and will always cause drag or pull on the stylus in the groove.

Well engineered air bearings are very low friction, potentially far lower than gimbal bearings on pivoted arms.  Positive design features are very accurate machining - Aeroarm has a 5mu air-gap.  And vibration-free high and constant air pressure to fill the air-gap and keep the bar and tube in a steady-state relationship and not impose jitter or eddys.  Operating theatre compressors aren't cheap but do an excellent job.  They should be sited in a different room, a long way from the TT.  Don't use fishtank compressors, even big ones.

It is fundamental to prevent the stylus moving relative to the TT chassis, save as driven by the groove walls.  All other movement is other than what is in the groove and will be transmitted as distortion.

So pivoted arms hung on strings are utter nonsense.

Unipivots are also inherently unstable in that respect, so difficult to engineer.  Damping will tend to cause drag, although nearly all are damped, usually with liquid or gel.  The only solution is to site the pivot high relative to the record surface, but there will still be a tendency for the contraption to swing and allow the stylus to move from lateral perpendicularity in the groove.  Even a little of this is VERY bad.

@mijostyn

But since you Mention the Eminent Technology arm, it is a rip off of the Walker Proscenium arm. 

Unfortunately your comments on the Eminent Technology tonearm are wrong and ill-informed.

Bruce Thigpen, the designer and owner of Eminent Technology products, was the designer of the old Coloney/Mapleknoll  air bearing turntables and tonearms. Bruce moved on to form a new company and developed the Eminent Technology ET2 and other products.

Lloyd Walker took over the Coloney/Mapleknoll turnable business and designs and then developed the Walker Proscenium TT's from Bruces early designs. The Eminent Technology ET2 preceded Walkers own updates on the Mapleknoll TT's and air bearing arms.

Both are arms in search of a cartridge that does not exist. The cartridge would have to have three times the horizontal compliance in relation to vertical compliance. Thus both arms exhibit much more distortion than proper pivoted arms. 

The ET2 is far more sophisticated than the Walker arms. The patented decoupled counterweight, adjustable VTA on the fly using an arc block so that vertical pivot to stylus stays constant regardless of VTA position remains. As far as I know it is the only arm linear or otherwise that accomplishes this.

With the counterweight decoupled the horizontal effective mass of my ET2 is well under 20g, Thats less than many current heavyweight arms.

The decoupled counterweight in the horizonal plain ensures that the arm has different effective mass horizontally and vertically - similar to the Dynavector arms - which results in a substantially reduced peak resonance in the bass.

Your comments above on compliance and distortion are ill informed - you clearly have no understanding of the ET2 design. The effective masses both vertically and horizontally can be tuned individually to the cartridge via adjustable weights/position of weights on the I beam & variable decoupling rates.

The Walker has none of these features.

With regard to air bearing arms with motorised carriages - you can see them crabbing across the record - they dont work. I've worked with both.

If you want to get into Thales etc - well they have their own downsides - due to their design they lose rigidity thorugh their complexity - not the best way to measure the groove with a rattly arm. 

It is just like unipivot versus gimball bearings - there is no best - simply pros and cons of each design.

You mention Schroeder - his Reference arms hanging on a piece of string do not provide a stable platform for the cartridge. They are a joke. 

You should spend more time reading up on arm designs, it will help you optimise your own turntable regardless of which arm you prefer.

@dover, good thing because the forces acting on the tonearm cartridge system ( they are imminently attached to one another) are very simple. 
But since you Mention the Eminent Technology arm, it is a rip off of the Walker Proscenium arm. Both are arms in search of a cartridge that does not exist. The cartridge would have to have three times the horizontal compliance in relation to vertical compliance. Thus both arms exhibit much more distortion than proper pivoted arms. Air bearings are simple devices. You can easily buy a bearing and make your own air bearing arm more easily than you could make a gimbal pivot arm. Companies like SME or SAT could easily make air bearing arms but choose not to for good reason. The distortion added by tracking error is far less than what is added by an inordinately high horizontal effective mass. Linear trackers with motorized carriages are superior but difficult to design and build, far beyond a company like Eminent Technology or Walker. Better yet are arms like the Reed 5T and Schroder LT. Both arms have secondary horizontal bearings, one motorized the other magnetically guided that otherwise function as normal pivoted arms. They just stay tangent to the groove but, more importantly do not generate any skating force which is even more important from a tracking perspective. IMHO the Schroder LT is a brilliant design powered by the pull of the record on the stylus which transfers it to the cantilever, which transfers it to the cartridge, which transfers it to the tonearm and finally to the bearing platform pulling it forward while a magnet keeps the arm properly aligned. Brilliant. I wish I were that smart.

It is a bit confusing that some posters are saying that overhang or offset angles "cause" the skating force.  The WallyTools videos posted here that shows that, under specific conditions, skating forces can even be in the opposite direction, add to the confusion because they do not attempt to explain why this is so.  Overhang and offset angles don't directly "cause" skating forces, but, they do create the conditions that give rise to skating forces because they create the geometry that causes the force of friction (drag) to pull the arm in one direction or another.  

The drag developed at the point of contact of the stylus with the wall of the groove is pulling along a line that is a tangent to the points of contact of the stylus.  Whether this tangent is in the same direction as the cantilever or to the left or right of this line is dependent on the alignment of the cartridge at that particular moment.  For a reference point, imagine that a spherical stylus, when viewed from directly above, is a clock face with the axis of the cantilever bisects the 6 o'clock and 12 o'clock position.  When that stylus is at a point on the record where the contact is at the 9 and 3 o'clock position, the drag is directly along the line of the cantilever.  Will this result in skating force?  The answer is:  it depends.  If the alignment is such that the cartridge is perfectly straight (no offset angle to the headshell and cartridge), at that perfect tangency point on the record, there is no skating force because that drag is pulling straight back to the pivot point of the tonearm and that pivot is resisting that drag.  But, if the alignment is a conventional alignment, such as Lofgren B, at the point of perfect tangency, there is a substantial skating force, because the drag along the same line as the cantilever is pulling at a point to the right of the pivot point (because of the offset angle) and the pivot cannot completely resist that pull.  On the setup with a cartridge facing straight forward with no overhang, at points outside of the perfect tangency point on the record, the points of contact will not be at the 9 and 3 o'clock position, but something toward the 10 and 4 o'clock position; this means that the drag direct (tangent to these points) is aimed to the right of the pivot and so there is skating force.  At the point inside the point of tangency, the points of contact are toward the 8 and 2 o'clock position, so the direction of drag is to the left of the pivot an the skating force is now in the opposite direction.  The reason there is ALWAYS a skating force in the conventional direction with conventional alignments (e.g., Lofgren) is because these alignments minimize the deviation from perfect 9 and 3 o'clock contact (always less than 2 degree deviation) which is MUCH less than the fixed offset angle; this means that the drag is ALWAYs to the right of the arm pivot point even if does deviate over the diameter of the record.

@mijostyn

Actually I do run a linear tracker - Eminent Technology ET2

Not an English major, but understand force vectors - studied Engineering at University. However, most of the english on this thread is such poor quality, it is the very reason many are arguing the same point from opposite sides of the tangent, or debating at cross purposes.

You blank record analogy is false.

If you understood what a tangent is, you would know that the null point is momentary in time is the stylus passes through ( assuming the record is spinning ) with a pivoted arm.

When the stylus is tangent to the groove (null point) the pulling force caused by the friction with be inline with the tonearm’s linear offset, thereby causing a rotational torque around the tonearm’s pivot.

The forces are far more complex than you posit. The primary force (drag ) is on the stylus/cantilver, not the arm. As the stylus passes through the point tangent it is momentarily pulling the cantilever in a straight line. Yes, you have a hinge between the cantilever/elastomer and the arm, but this gets very complex if you want to model that. Furthermore you need to factor in whether the arm bearings are offset, and what sort of cartridge cantilver mechanism is in play.

This is why it is much more prudent the eyeball the cantilever under dynamic conditions to ensure it is remains straight and is not getting pulled one way or the other. Using formulae and theory to set antiskate is not the best in my view.

If you talk to cartridge retippers such as the original Garrot Brothers and AJ van den hul, they will tell you most cartridges they reveive have uneven wear arising from incorrect antiskate settings.  

For the record not only do I run a linear tracker, but also a cantileverless cartridge - Ikeda Kiwame. Antiskate arguments are moot.

As an aside, when I had a hiatus from audio tinkering some years ago, I ran a high compliance Shure V15vxmr in the ET2 for 10 years. The cantilever was still dead straight after 10 years of running, despite the high horozontal mass of the ET2. 

@millercarbon could you post a link to any article that supports or further explains your skating force theory. 

@dover , I think you might do better with a straight line tracker.

@millercarbon, no reason to be condescending. Dover was probably an English major and missed the lecture on force vectors.

People who are having a hard time with this, get a blank record and do an experiment. Defeat your anti skating mechanism and put the stylus down on the rotating blank record. It will go zinging straight for the spindle. It will not stop at the null points. If the spindle doesn't stop it it will continue right off the other side of the record due to the overhang. If your overhang is not set up correctly you could smash your cantilever and do a number on the stylus's zenith not too mention it's tracking angle, azimuth, SRA and your wallet.

Incredible the amount of confusion generated by such a simple thing. Given a teeter-totter you guys would figure out a way of explaining it that would go on for years and never get there.

Pivoted arms use a geometry that is cobbled together from a need to compromise several conflicting goals. Try not to confuse and conflate the different goals!

When the stylus is tangent to the groove (null point) the pulling force caused by the friction with be inline with the tonearm’s linear offset, thereby causing a rotational torque around the tonearm’s pivot.

This loopy logic results from confusing the STYLUS being tangent with the line from the stylus to the arm pivot being tangent.

We got a couple things going on. Seriously, keep them straight! 

We got a line that runs from the stylus to the pivot. When this line is tangential to the groove then groove drag is perfectly in line and there is no skating force. Period. Does not matter which way you rotate the cartridge, head shell, or any of that. Stylus to pivot perpendicular to groove, zero skating force.

This however is not gonna play music very well! So what we do, make the arm longer. The stylus now overhangs and is beyond tangent. The angle it is off is a vector and that vector force is pushing the arm towards the center. Head shell angle, offset, cartridge alignment DOES NOT MATTER! All that matters as far as skating force is concerned is the overhang. 

Say again, as far as skating force is concerned! Which, according to the title at the top of the page is the subject we are concerned with here. Skating.  

Skating forces have been explained absolutely perfectly by me about a dozen times now. Where people deliberately go confusing is adding in other stuff that we do that does matter but has nothing to do with skating!

The reason for some head shells being cocked off at an angle, or offset, or whatever, cartridge alignment, is all completely different. Now you want to talk about that, fine. But please understand we are no longer talking about skating. We are now talking about tracking angle.

Because the same overhang that introduces skating also puts the arm out of tangency, and this introduces tracking distortion. So we rotate the cartridge trying to get it back at an angle that is tangent.

This is where the cantilever is tangent to the groove. Please note, this is NOT the stylus-pivot being tangent. This is the stylus itself being tangent. We cannot see the stylus, so we use the cantilever as a proxy, and hope the manufacturer has done his job and the stylus is aligned.

Very, very, very important we keep all these thing straight. Each and every one. ALL the confusions above are people conflating, talking about similar but different and sometimes completely unrelated things as if they are all the same. They are not all the same. Get it straight or get it wrong.

I wouldn't mind so much, except playing records is really fun, easy, and sounds great. Until someone comes along with a simple question, and you guys make it seem impossible, and an endless struggle to boot! It is just not that hard. But no one can tell, not from reading stuff like this!

@dover 

Not wishing to stretch this overwrought saga out, but this is not correct.Skating forces are due to the offset headshell/cartridge AND the pull on the stylus.At tangent the inward skating force is zero, and therefore at the 2 null points it is zero

How can this be true?  When the stylus is tangent to the groove (null point) the pulling force caused by the friction with be inline with the tonearm’s linear offset, thereby causing a rotational torque around the tonearm’s pivot.  Only a zero offset underslung tonearm will exhibit zero skating at the null point as Lewn has pointed out numerous times