Set-Up Tips

I've always wondered about the topic, and finally it's answered.

Skating is just a fact of life for pivoted, offset tonearms with overhang.
First of all I am not schilling for anyone.
This is where tangential tonearms can shine. With minimal skating forces the stylus is left to do its job without interference. But the problem with most tangential arms is a horrifically high horizontal effective mass, worse than skating! There are now two tonearms that provide tangential tracking without the need for an anti skating devise and have horizontal masses similar to any pivoted tonearm. These are the Reed 5T and the Schroder LT. Michael Fremer just published a favorable review of the Reed. I think that if he had an arm wand with a higher effective mass the bass performance would improve in line with his SAT arm. The Schroder LT is a brilliant exercise in lateral thinking. It does exactly the same thing as the Reed but without any Lasers and servos. I am hoping Mr Fremer will be able to review that arm. No anti skating required:)

Since we're discussing Wally, he got to the bottom of correct effective length year ago. He originally made Tractors based on the spec you've quoted from Rega. It turns out there isn't any engineering behind those numbers. The thought was Rega reused Tribal knowledge from when the R200 days and 15mm was the spec provided from the manufacturer in Japan. This was causing problems with alignments that were reported to him on forums. He corrected the issue. So he contacted Clearaudio to get an actual engineered answer. This is what he got and changed the corrected effective length (Baerwald) to 239 mm. Some of the disparity has do with Rega using a Stevenson based alignment. He corrected the distance on Tractors made after this discussion and offered trade-ins if you bought one with the incorrect length. My Wally Tractor has the corrected length of 239mm.

"P> Sp = 221.7mm. This fixed distance requires (for Baerwald alignment) Ovhg=17.3mm and Leff will be 239mm."

https://www.audioasylum.com/cgi/t.mpl?f=vinyl&m=180289

Apart from issues of uneven stylus and groove wear due to skating forces or excessive anti-skating you also have the cantilever responding unevenly to the groove modulations because more force is applied on one side of the cantilever than the other. Visualize a spring lying horizontally with more pressure applied on one side. It will require more force to spring back to that side. Or maybe I am looking for problems where there are none.

All tangential arms that drag a carriage along a straight path may be just as bad as anti skateless arms in terms of effects on tracking, stylus and groove wear. Their horizontal effective masses are just too high. The stylus and cantilever have to drag them along, back and forth if the record is eccentric. I never purchased one for this reason. The Reed 5T and Schroder LT defeat this problem. Now, nothing is perfect. For these arms to be perfectly skateless the record would have to be perfectly flat, the turntable leveled perfectly and the arm positioned dead on tangent. I do not know how the Reed is set up But the Schroder handles this problem by supplying a special flat grooveless record. With the stylus down on the record you can see how the arm is drifting. There is an Allen screw adjustment that alters the angle of the horizontal bearing platform and the position of the stylus relative to the tangent.
You adjust it until the arm does not move. It is still not perfect but it does guarantee that any skating forces developed are minuscule in comparison to any other type of arm. This is different than using a grooveless record for adjusting anti skating in an offset arm which I think we all agree is a bad idea.
The problem with skating is there is no way to compensate for to near perfectly, too many drifting variables. Good arm do compensate for it reasonably well allowing the stylus to track just about any record.
These two arms are the only two that I know of that avoid the problem altogether. There is no skating force in the normal sense. I would hope this type of design will drift down to lower price points. In the meanwhile the Wally Skater has a huge target audience:)

Thank you for this fascinating stuff.

Daft. The first 3 videos demonstrate little. Twisting the cartridge in the headshell affects either the official arm offset angle (which is the the angle between a line drawn from the stylus and the arm pivot and a line drawn from the stylus parallel to the headshell), nor the instantaneous effective offset (which is the angle between the a line drawn from the stylus to the arm pivot and the angle of the force vector caused by friction on the stylus). The rest of the videos demonstrate the effective offset angle varies with overhang, not that overhang causes skating.

This is the Analog Planet content I am used to! Well done Michael!
I do get into the weeds as far as I can with things like turntable setup and record cleaning, (I probably went too far into the forest on that, but glad I did in the end).
Anyway, this whole thing gave me more confidence in the mechanisms on my tables. I have stock vintage tables with S-arms with the exception of my Denon DP47f. On the Denon the anti-skate is set automatically electronically. Don't ask me how it does that, to me it is magic. I'm fairly intelligent on things audio and physics and such, but I'm not a genius.(I can't design a turntable or what have you). I just know how to set them up. (I learned from Michael and a couple other sources years ago).
While the Wally tool would not be worth it for me to get in my situation I am still glad you made this info available. It helped me confirm I am doing things correctly for my tables. I mean, I can tell by sound alone as could anyone, but it is just nice to know it to identify what is the small stuff and what is not and that I personally don't need to worry. (If I had a different table though, it may be a different story).

In front of such complexity (And In a context where some well know turntable manufacturers tell us to not bother with anti skating) why is it so bad to use a blank record? At least one gets a sense of the forces at play.
The friction might be weaker than on a modulated groove but it doesn’t seem to be a bad place to start.
Adjust the anti skating to steady the arm on a blank record and then give it ‘a little extra’ ?
How bad can it be?

Particularly the first slide in the PDF. I've never seen it laid out so clearly. Thank you!

given that turntables command four, five and even six figures, I’m guessing this issue is not one that affects the sound that much. First world neurotic audiophile problem?

Michael,

What are we to make to Harry Weisfeld's dislike of skating compensation? He claims he can hear it working as the cartridge makes its way across the surface of the record, with images shifting around and the soundstange skewing in the process. So he doesn't recommend applying any antiskating force to his tonearms.

Based on his stance, is it possible that the cure is worse than the disease?

Question: Michael Fremer sir, but also WAM Engineering, is that a bad taste joke? Or (with all due respect) you just have lost your minds?

The twist of the cart (so its cantilever) does not affect the direction and the vector of friction which is always the tangent to the circle passing through the point where the spherical shaped needle is located into the groove. The vector of the friction, the only thing it knows is that a (special for the purpose) spherical needle is in the groove, so it (the vector) is oriented as the tangent of the circle passing from that point. 
This direction of the friction force vector by itself determines the offset angle, regardless of where the cart and its cantilever are facing.
Therefore, no matter how much you turn the cart, either targeting the tonearm pivot, or even to its left, nothing can change the offset angle of the friction force, so always there is a torque with respect to the tonearm's pivot creating the skating force.
But the most hilarious of all is that, while they suggest us, insisting not to use a blank grooveless record for adjusting anti-skating, they are contacting all they experiments in ....a blank grooveless record!! Period.
P.S.1 There are some equally crucial errors in your assumptions, but for those, another time.
P.S.2 Michael Fremer also says, that through this new theory he discovered that analog guru and his mentor late Wally Malewicz had misled him on a/s issue all those years!!!!
A statement that I consider offensive in the memory of the dearly departed, who taught him (and us) and offered so much to the evolution and proper adjustments of analog sound!

Concerning the "No overhung tonarm" which
just "discovered" and presented in the above article, there is an elementary school's mediocre student's error (in order to support their theory).
Namely they shape an isosceles triangle, which has:
a. its apex in the tonearm pivot,
b. its two equal sides are, one is the line that joins the pivot to the spindle, and the other is the line that joins the pivot with the needle as a tangent on the circle passing from the point where the needle points.
c. its base is the radius from the spindle to the needle, so it's vertical to above tangent, namely vertical to the one of the 2 equal sides of the triangle!! So we have an isosceles triangle that it has the 2 equal to each other angles to be each one 90 degrees, which means that they discovered a triangle whose sum of angles is greater than 180 degrees !!!
OMG!! The bones of Wally Malewicz will definitely be crunching ....

I believe the diagram showing zero overhang in Mr. Boisclair’s PowerPoint presentation (slide 2) is incorrect and is actually depicting negative overhang (underhang?). Zero overhang is when the pivot-to-stylus distance is equal to the pivot-to-spindle distance, but the diagram shows the stylus set at a distance that is less than the pivot-to-spindle.

Here's my rough revision of that slide, correctly depicting zero overhang.

https://gallery.audioasylum.com/cgi/gi.mpl?u=32746&f=wallytools_zero_ove...

Tom

I think we can agree on several issues. First is skating exists. And, the most important driver is friction between the stylus and the groove. Unfortunately, this is not a constant. Thus anti skate is a ballpark adjustment. The right value is the one that compensates perfectly for the average skating force across the record. Accept for one exact level of friction the stylus is always going to be leaning a little one way or the other. The problem with leaning a lot one way or the other is miss tracking the unloaded side. This is what would cause the most record wear and audible distortion. The threat of miss tracking increases with groove velocity (modulation) as does friction. I currently use miss tacking to set anti skate. I would be interested to see how the Wally Skater agrees or disagrees with this method.
Now for the blank record. Using a blank record increases, let me say that again, increases friction and would cause you to overestimate the anti skating force required. When you place the very tip of the stylus on the blank record you are dramatically increasing the pressure (PSI) seen by the vinyl so much so that that the stylus digs into the vinyl. Try it and you will see a shallow spiral groove cut by the stylus. The analogy is this. What would be easier to slide over ice, the tip of a pick ax or the face of a hammer. With the stylus in the groove the amount of surface area in contact with the groove essentially doubles halving the pressure (PSI).

The hammer face is certainly going to slide over gravel easier than the pick ax point. The frictional forces will just be higher for both than over ice. I used ice in this analogy because we were talking about a blank record not a modulated groove. This holds true for groove velocity(modulation not speed). The major determinants of skating are stylus pressure (maybe better quantified as PSI vs VTF?), groove modulation and position on the record. Minor determinants are overhang, stylus profile, and tonearm geometry.
The point of all this is how to find that best average value. There are several reasonable methods including the Wally Skater. I seems to me the Wally Skaters chief advantage is that it produces a repeatable value without depending on someone's ability to hear distortion or determine what a slow drift is. It's problem is the price. If it is more accurate or produces better results it is certainly worth it for someone who sets up a lot of turntables like Mr Fremer who is constantly changing cartridges.

just like I get that if I put all my weight on one foot I'll sink deeper into the snow than if I put it on both.

What I am saying is that it is a bit too simple an analogy. Lots will depend on the stylus profile etc. It rings true with an elliptical that has large contact points with the sides of the groove, does it with a conical? It also rings true in a silent (ice) part of the groove, you just split the pressure on two points on a similar surface, ok, but that's not the part of the groove we're interested in :) There are so many factors (you point at some of them) but wouldnt also the type of drive, stiff belt, springy belt, direct drive influence things too? There are so many factors that I think we agree (See my first message) that we're aiming at a ballpark. And that although anti-skating is needed, it's not a super critical setting.

Very convincing videos. However, in video 4 either the explanation is either incorrect or I have misunderstood. If the spindle to pivot distance is identical to the cartridge (stylus) to pivot distance, the line from stylus to pivot cannot be perpendicular to the line from the stylus to spindle. In other words, the base cannot be equal in length the hypotenuse in a right angled triangle. Please enlighten me.

Hans

My peasant thinking about anti-skating for the last two hundred years of vinyl playing has been this. (1) Imagine a tangential tonearm (actually the same concept applies to a pivoting arm but bear with me as the concept is clearer with a tangential). That tonearm is ideally tangential. (2) Now imagine that on a 12 inch lp that tonearm is two inches too long. What is happening? Instead of the groves flowing tangentially they are flowing left to right (from the view behind the tonearm pivot). (3) now imagine you have a tonearm that is way too short. The groves are moving right to left (again from the view from behind the pivot). So they are pushing the stylus outwards.

I had long 'understood' that the paddle effect of the angle of offset pushed the stylus inward - the analogy being the rudder of a boat. I accepted that but did not understand how that worked given the circular shape of the stylus (looked at from above). Now I see that the offset is indeed irrelevant.

These are the best clips on Youtube for understanding offset and antiskating.

I do have a question. This relates to pivoted arms. There are said to be two null points, on say a Lofgren alignment. It seems to me that on the arms beginning the stylus would be underhung (shame!) and there would be some outward skating force. At the first null point all would be good. After the first null point there would be some overhang and some skating force toward the center. This would increase then decrease to the second null point where there would be no skating force in either direction. Then there would be more underhang and thus skating would be increasing outwards.

Question. Is this why on your vids that the 'neutral' middle zone shows a bit of sway?

In the preview article to this topic (WAM Engineering's New, Improved WallySkater V2.1, Michael Fremer | Aug 2, 2020), one comment stated "skating force basically occurs because of overhang of pivoted tonearms..." to which Michael replied, "That.....Is correct."

The article here then states «...no overhang does eliminate skating at the point of tangency as demonstrated in the video, but only at that point and in fact, beyond that point the arm produces its own “anti-skating”...» -- Michael is contradicting himself (first he agreed skating occurs because of overhang, then says skating occurs with no overhang except at one radius). I get no amusement from it.

Let me first clear up that what he calls "anti-skating" for the no overhang case is really skating, not anti-skating. Skating is a force at the stylus, anti-skating is applied elsewhere with the intent to counteract skating. As was plainly shown in the video, skating may be either inward or outward and both cases arise from the same cause, so calling one case "anti-skating" is just plain idiotic.

Now concerning overhang, the discussion in video #6 seems lacking, which is rather peculiar following what was shown in video #5. Skating was shown to occur no overhang -- at larger radii the skating was inward, and at smaller radii it was outward, with one radius between the two ranges where no skating occurs. Perhaps video #6 could have prevented Michael's confusion by explicitly stating what had been demonstated: the standard overhang ensures the skating force will always be radially inward. And you can expect an anti-skating system will be easier to design if it only has to apply its corrective force in one direction.

The groove-less experiments do not control all variables well (e.g. the levelness of surface0 and also does not agree with what's happening in a groove. For example, the friction comes from the tip of the stylus against a flat surface. In a groove, it is the sides of the tip that are in touch with the walls.

Wally was mostly correct, this is just plain law of classical physics: side force/momentum exists when playing a record if the cartridge's cantilever does not align with the pivot point of the tone arm. Even in arms with no offset angle or linear tracking arms, the cantilever may not be entirely parallel to the arm tube, hence inward or outward side force will be generated.

When side force is present as the stylus is playing in the groove, the groove wall will stop the stylus from moving sideways, but the arm's momentum will exert force on the damper/suspension of the cartridge, making one side of it preloaded. If the stylus and cantilever wants to move in the preloaded direction, beyond certain degree the damper/suspense "bottoms out", and mistracking occurs. This is very visible by playing test signals and observe the wave form on a scope. In a typical pivoted arm, if no anti-skate force is applied, the stylus/cantilever will be pushed outward by the inner groove wall from the arm's inward momentum, loading the outer (right channel side) part of its damper/suspension. As a result, the right channel tends to distort/mistrack much easier since stylus/cantilever tends get impeded by the bottomed-out damper/suspension when moving outwards.

The anti-skate force is necessary only to prevent the bottom-out situation in the cartridge's damper/suspension, and this means that the softer the damper/suspension, the less anti-skate force is needed, assuming all other factors being equal.

A. Cartridge's cantilever not exactly in line with the arm's pivot point: this includes pivoted arm with or without offset angle, as well as linear tracking arms.

B. Torsion force exerted on the stylus tip when both sides of the stylus do not have equal friction forces.

C. Others: off-center spindle holes of record, non-level record surface, etc.

Overall, A remains the strongest source due to the inertia/momentum from the arm.

Anti-Skating and Side Force, Part#1: Classification of Various Side Forces during Vinyl Record Playback

https://bingrungtsai.blogspot.com/2021/11/classification-of-various-side...

As we view from the front side of a cartridge playing a record, the side forces exerted on the cartridge's stylus/cantilever will be parallel to the record surface, and (mostly) perpendicular to the cantilever. For easier discussion below, the direction for side force toward the center of the record is termed "inward", whereas the direction toward the rim of the record is "outward".

During vinyl playback, given proper tracking force setting, the majority of tracking distortions or "break ups" are due to the existence of persistent side forces causing uneven loads to the damper in a cartridge. When the damper, like a spring compressed to the limit of its normal operating range, cannot accommodate the cantilever moving in certain direction, the stylus will fail to follow the trajectory of groove modulations. In other words, in such situations, the damper is not able to yield further to allow the cantilever to move freely, as such the stylus cannot trace the signal properly, and distortions occur. Only in uncommon situations the distortions result from groove modulations surpassing the tracking capability of the cartridge, mainly seen in cartridges with unusually stiff dampers.

The characteristics of side forces can be divided into two major categories. In the first category, the direction of the force alters at about 1/20 second or longer period, or even not changing direction at all for the entire side of the record. This directional-change rate is at or below the low-frequency resonance of the cartridge-arm combo, hence such force CANNOT be effectively absorbed by the damper in the cartridge, thus propagates between the tone arm and the cantilever of the cartridge and is stored in the cartridge's damper as potential energy. This category will be termed "DC-mode" side force, for its similarity to the Direct Current in electricity which the current flow does not change direction.

In the second category, the direction of the force alters rapidly, similar to the AC electricity. Such side force manifests as kinetic energy and is quickly stored and then released by the damper in the cartridge.

=========================================================================

Category of side forces, Group 1:

(1A) When playing a record, each side of the stylus contacts the groove wall and generates frictional forces. The forces drag the cantilever forward as in Figure.1. In most cases, the extended straight line from the cantilever does not precisely coincides the pivot point of the tone arm, a torque force is therefore generated which pushes the arm assembly in or outward.

(1A-1) For pivoted arms (either conventional or tangential) with an offset angle, as in Figure.2 below, the drag on the cantilever generates forward force (red arrowed line) , together with the blue line indicating the moment arm, generates inward torque acting on the tone arm.

(1A-2) In linear tangential arms or straight pivoted arms, both without offset angle, if the cantilever of the installed cartridge is not precisely pointing toward the pivot center, the drag on the cantilever during play can still generate inward or outward torque on the arm.

(1B) When the spindle hole of the record is off centered, the rotation of the record will bring the cartridge and arm assembly inward and outward alternatively at about 1.8 second interval, hence generating side forces.

(1C) The surface of a record is not entirely level, causing uphill and/or downhill effects as the cartridge plays and the arm moves toward the center spindle.

=======================================================================

Categoriy of side forces, Group 2:

(2A) As a stylus interacts with both groove walls, especially for stereo records where the two walls are engraved with different signals, the two contact sides of the stylus may take on forces of uneven magnitudes, generating rotational torque on the stylus shank, then propagating upward to the cantilever. Depending on the signal contents, such torque can quickly appear, disappear, and the rotation can reverse directions, all in very short period of time. The time window is typically much less than 1/20 second. The damper mechanisms in most cartridges can easily absorb such transient torque force, and prevent further propagation upward to the arm.

(2B) When playing musical signals, the stylus will move along with the groove walls back and forth, with frequency range from around 20Hz to more than 20kHz. The force and energy acting on the stylus propagates upward and will mostly be absorbed by the cartridge damper.

=======================================================================

In general, the two major groups of side forces coexist during play. (1A) is a much greater and more persistent source of side force than (1B) and (1C). And Group 2 side forces are not only weaker, but also transient in nature and are nearly entirely absorbed by the damper.

Consequently, Group 1 side forces should be the focus for further research and discussion. (1A), (1B) and (1C) types of forces may add or subtract to one another, although (1A) which includes (1A-1) and (1A-2), remains the most dominant and influential of all. Consequently, the design and adjustment of anti-skating mechanisms in pivoted arms and the minimization of side forces in linear tracking arms should consider these as critical factors.

Group 2 forces are absorbed by the damper, consequently changes in their intensities will not affect the tone arm. This in term implies the difference in signal strengths do not change the required amount of anti-skating force in pivoted arms.

Incidentally, since the amount of dynamic friction force is near constant at low speeds, the friction generated between the stylus and groove walls remains unchanged for outer grooves and inner grooves, even though the relative linear speed is reduced by half. As such the applied anti-skating force should ideally stay constant during play for pivoted arms. More in-depth discussions on this subject will continue in a future write-up.

So I guess a record without grooves is pointless to fine tune the anti-skatting?

Like this:
https://www.dienadel.de/anti-skating-test-schallplatte-die-rillenlose-te...

You can read the instructions in English, in one of the photos.

I am coming "late to the party", but least anyone take the assertion of 'So much for “offset angle creates skating” (forces)' to heart, I want to point out that a flat un-modulated LP cannot fully simulate the frictional components that come into play with a modulated (grooved) LP.

Given that the diamond stylus 'apex point' is the only "point-of-contact" sitting on the (flat/un-modulated) disc, and given that this is a 'very small' contact surface-area. we can expect to generate some (but not all) of the frictional skating forces that come into play when you are playing a modulated (grooved) record. In this case -- with this setup -- changing the angular offset (given the very small point of contact), does not incur any additional frictional force that you would get if you did the same with a modulated LP (w//grooves); Especially if you maintained the 90 degree side-to-side, plus horizontal fore-to-aft orientation
to the surface of the disc.

The video behaviors you show and observed are consistent with the current skating-force theories, even though you tested with 'extreme' "negative offsets." Given the stylus single point-of-contact, the orientation/rotation of the stylus within the head-shell makes no difference, other than to slightly change the stylus "apex-point" to pivot-point distance. So the arm is pulled inwards with the same 'identical' alacrity, regardless of cartridge offset.

Skating force is predominately driven by stylus friction on vinyl, and the force increases when tracing the groove walls (as there is 'more' vinyl in contact). The skate-force and the skate-force 'vector' comes from the fact a tonearm acts as a "fixed-end" fulcrum , as it has a fixed pivot point at one end of the
tonearm with (typically) "low-resistance to movement" bearings. When grooves are introduced, the stylus surface contact area increases, which increases the friction. Changing the angular-offset in the grooved case can expand the surface area, creating more friction. So the correct observation would be "the offset angle can help create additional skating forces." After a fashion, your statement [So much for “offset angle creates skating”] is partially "true", as skating is not 'directly' caused by off-set angles.