Anti Skating?

mtemur

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Mar 26, 2019
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Can you please share with us how you came to this conclusion? How do you measure this deterioration?





Jelco's first mode is slightly below 300 Hz. I am yet to see any tonearm with a resonant mode below 50 Hz. What are your conclusions based on? You say the tonearms are supposedly "not rigid enough". How did you measure it?



What can possibly be a source of movement in the 0-20 Hz range of a 2 inch hardwood desk screwed to a 45 cm basement concrete wall? Where this interference from the outside world come from and how will it affect the measurements?



Oh pity me, my life is now ruined. But before I take my monastic wows and forego the secular life altogether... Can we please see any objective data on which you base your opinion?
Cartridge dampers deteriorate. If you don’t think they do, I can’t help you. Sometimes you can see deterioration visually sometimes not. It can be tested using a 7-20 or 30Hz frequency sweep on a test record or it’s best to send it to a professional for inspection. I do it using computer software to record the track and analyze the FFT graph or I use AM software. It can simply be done by looking at cartridge movement. It requires experience, I can do that but that’s not scientific. If you’re checking your cartridge at home it’s ok but if you’re going to declare the world that everybody is wrong you can not take any chances.

Claiming that “accepted wisdom turned out to be completely wrong” about Tonearm-cartridge resonance calculations is a bold sentence and release it over a web blog is even bolder which requires a more professional approach.
- At least you should have sent cartridges to a professional to be inspected.
- A better approach is choosing 3 new cartridges from well respected brands with different compliances and buying 3 from each (9 in total).
- Sometimes new cartridges have suspension issues. It’s a better and more scientific way to have 3 new examples of the same cartridge. That’s why buying 3 from each cartridge makes sense.
Instead of doing those things experimenting with old and used cartridges which have suspensions at unknown condition is not the proper way of proving the world is wrong.

Reaching to a conclusion like : Modern cartridges (meaning all those built in the last 60 years or so) have too much suspension damping and non-linearity for the resonances to dominate” with only 3 basic cartridges (Shure M97, Ortofon SL15 and Denon DL103) at unknown condition is pretty prematurely conclusive.

Reaching this conclusion: “The frequency of the observed motion is determined largely by the frequency of the excitation” or this one: “ The cartridge/tonearm system acts as a lowpass filter for vibrations picked up by the stylus” using one basic arm (Jelco) and 3 old cartridges is again unnecessarily conclusive due to reasons I explained above.

That’s enough for now.
 
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bazelio

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Another inconclusive data point.... But I've stopped worrying about "the formula" for cartridges in my own listening environments on my record players. I've tried to empirically determine via listening and measuring the utility of adhering to the formula and all I've been able to actually determine has been that the formula isn't useful for much other than hand wringing. My favorite cartridge/arm combos shouldn't be recommended per the theory and I don't see any measurable anomalies under various conditions in the listening space. Horses for courses.
 
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mtemur

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Ok thank you. As I suspected, you cannot answer a single one of my questions. A lot of sound and fury, no data.
You’re welcome. As I predicted your approach is pretty amateur as well as your response.
 

AlexKorf

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*I'll defer to alex for a deeper dive into this (welcome Alex!)

Thank you for the welcome Dave!

Repeating your experiment is extremely easy indeed. Repeating mine is a bit more involved but is still trivial. Nobody's willing to do it—can't imagine why?

And, of course, you're right. Elastomer aging does not figure into this at all. As most elastomers used in the cartridges age, their low frequency behaviour stays virtually the same right to the moment of failure. The hardness/frequency curve does change rather a lot, but this is not relevant to f<100 Hz.
 
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Yeti

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the math says that doubling the mass should 1/2 the Fres and in my experiences I have yet to see this happen. the Korf audio guy found the same thing but in his case he changed the compliance. http://korfaudio.com/blog70

dave
I didn’t actually run it on a test record but the tendency of a London Decca Maroon to jump out of the groove of a stereo cut was greatly reduced by adding a bit under 8g to the headshell of an 11g eff mass arm, It was nearly as effective as a Townshend damping paddle and trough, the padle part of which was nearer three grams.
Not sure what this has to do with antiskate.
 

Bacek

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I personally wouldn't believe anything HW says; he has made numerous patently false statements in the past including statements about tonearm geometry, so I don't think he really understands much about the subject. He maintains that their 14" tonearm with no headshell offset has two null points on the record and exhibits no skating force at all; both statements are incorrect. With no headshell offset angle, there is only one null point and the tonearm will experience both CW skating torque (past the null) and CCW skating torque (before the null).
On one hand you are right. But on the other skatikg force is in function of offset angle + tracking angle error. On tonearm with offset angle it's around 20 degrees +/- error tracking angle (lets assume maximum 3).
On tonearms with no offset angle this is much lower cause it will be as you wrote only tracking angle error. Of coure on underhang arms it will be greater then 3 degrees but still less then about 23 so skating force should be much lower there.
 

mtemur

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On one hand you are right. But on the other skatikg force is in function of offset angle + tracking angle error. On tonearm with offset angle it's around 20 degrees +/- error tracking angle (lets assume maximum 3).
On tonearms with no offset angle this is much lower cause it will be as you wrote only tracking angle error. Of coure on underhang arms it will be greater then 3 degrees but still less then about 23 so skating force should be much lower there.
Skating force has nothing to do with offset angle or tracking error. Skating force is purely related with overhang. Overhang determines how much skating force will apply.
 

Yeti

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Overhang and offset might just be linked somehow if you’re hitting the null points you’re trying for.
 

Bacek

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Skating force is purely related with overhang. Overhang determines how much skating force will apply.
I completly don't agree with that.
Underhang arms basicaly don't have any offset angle. So on one hand skating force is much lower for them and changes in direction so compensation would be too complicated.
But I will ask, how? What is the mechanics of overhand influenced skating force?
If you cannot explain it you can point me to any sicience paper on this topic.
 

J.R. Boisclair

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Jun 30, 2020
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There are several papers written on skating force over the last century. Kogen comes to mind but I can’t recall the others. Some of the authors were simply wrong about the cause of skating force. I did a video series demonstrating how offset angle doesn’t cause skating.
Offset angle is a third order derivative of the geometric function which causes skating. Overhang or underhang is a second order function but you can at least demonstrate skating by manipulating over/underhang, unlike offset angle which won’t change skating at all. See my early video series on this for a demonstration.
There are two elements that cause skating force: friction and a geometric function called effective moment arm. I far prefer using effective moment arm to describe how skating works because it can be used to actually calculate the horizontal torque force caused by skating and define how skating force changes with record radius and over/underhang.
See more on this in the download at the end of one of my two articles in skating force: https://www.wallyanalog.com/blog
I cannot recall which one of them has the download but hopefully you’ll find both helpful.
 
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mtemur

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Underhang arms basicaly don't have any offset angle. So on one hand skating force is much lower for them and changes in direction so compensation would be too complicated.
That is right. Underhang arms change direction of skating force and requires less anti-skating correction. There not many underhang arms around, almost all pivoted arms designed with overhang. When you switch from overhang to underhang value and direction of skating force totally changes. This is a clear proof but I will send you a couple of articles about it anyway.

I completly don't agree with that.
It’s up to you but that’s the truth. Skating force is related with overhang (underhang).
 

Bacek

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When you switch from overhang to underhang value and direction of skating force totally changes. This is a clear proof but I will send you a couple of articles about it anyway.
Are there any tonearms with overhang and whithout offset angle? I don't think so, Otherways they would have no null points at all and massive tracking error (for 9 inch arm close to 20 degres, so close to offset angle of 9 inch arms).
That is why (offset angle) for overhang arms, skating force has single direction.
So even if value of offset angle is not directly connected to value of skating force, it's directly connected to it's direction and without it, there is no skatting force in null points.

For us of course it's important, for example to have two null point and small tracking error but
from a point of view of a needle tip and tonearm, something like overhang or underhang does not exist. There is just moving record groove, friction and tracking angle/tracking error..


Thanks for materials to watch/read.

For a long time I'm tempted to create JIG that demonstrates how/why skating works and probably it's time to start it.
 
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mtemur

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Are there any tonearms with overhang and whithout offset angle? I don't think so, Otherways they would have no null points at all and massive tracking error (for 9 inch arm close to 20 degres, so close to offset angle of 9 inch arms).
The main purpose of overhang is to achieve at least a null point where stylus or cantilever is tangential to the groove. The main purpose of offset angle is adding second null point. The idea behind these is to reduce tracking error by carefully placing two null points.

That is why (offset angle) for overhang arms, skating force has single direction.
No, skating force direction is always the same, towards the spindle because of overhang not offset.

So even if value of offset angle is not directly connected to value of skating force, it's directly connected to it's direction and without it, there is no skatting force in null points.
No, there is skating force at null points but no tracking error if cartridge is optimally aligned on a pivoted overhang arm.

For us of course it's important, for example to have two null point and small tracking error but
from a point of view of a needle tip and tonearm, something like overhang or underhang does not exist. There is just moving record groove, friction and tracking angle/tracking error..
Orientation of stylus or cantilever is not relevant when it comes to skating. Concentrate on vectors stylus to pivot, stylus to spindle and groove tangent line.

I recommend you to check @J.R. Boisclair post again.

Here is an article I shared before on this topic:
 

Bacek

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No, there is skating force at null points but no tracking error if cartridge is optimally aligned on a pivoted overhang arm.
Overhang arm with no offset angle and at least one null point doesn't exist. This kind of arm would have no null points at all. Aligning cartridge (other then keeping cantilever aligned with tip to arm pivot axis) creates offset angle.
Straight arm is not no offset angle arm if cartridge is twisted because offset angle is property of cantilever.

And if we will take underhang arm with no offset angle in null point then force vector from arm pivot to needle tip is same as tonearm axis (for straight arm) and same as cantilever axis so no skating force can exist in this exact point.
 
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Bacek

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J.R. Boisclair

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I watched your movie. Looks like it proves your point but I still have some doubts. In your experiment you have used flat record, so here is no grove that holds tip in place. So effective vector of the force on needle tip in this experiment can be completely different then one on real record.
The tonearm pivot cannot “see” where the frictional force is distributed on the stylus. Any friction generated on the stylus - regardless of any asymmetry in the frictional force distribution - is transferred to the pivot of the arm along only one horizontal vector.
However, if one made a tonearm with two separate armwands joined at a common pivot but separated by an acute angle and the stylus on one of those armwands experienced greater frictional drag than the other, then the armwand with greater frictional force would dominate the position of both armwands.
This situation does not apply at all to analog playback, of course.
On a level plane, skating force is properly calculated and fully explained using the effective moment arm and coefficient of friction.
The video series was not meant to show what causes skating. It was only to demonstrate that offset angle is NOT a factor in it.
 

mtemur

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You can set anti-skating using a cheap VTF scale. Turn the scale on only after you placed it just like the one in picture. ~%11 VTF for 9” and ~%9 for 12”

IMG_0241.jpeg
 

J.R. Boisclair

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Jun 30, 2020
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You can set anti-skating using a cheap VTF scale. Turn the scale on only after you placed it just like the one in picture. ~%11 VTF for 9” and ~%9 for 12”

View attachment 128107
You'll have to verify that the strain gauge is not giving off false readings due to new vector forces, so you still need something "true" to reference its reading against when the scale is used in an orientation such as you have it there.

Assuming you've managed to get through that matter, you will also have to ensure the scale platform is orthogonal to the force direction in order to get a reliable reading.

How will you measure static friction without having the scale throwing off an unreadable result?
 

Zeotrope

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It's honestly best to set AS by ear. No tool is going to give you the fidelity required. Consider that AS itself is a moving target. To that you add a tool, which - no matter how precisely made and well designed - has it's own error.
It is not difficult to set by ear at all - just about an hour of trial and error.
I am not pushing any product and have no bias towards anything other than trying to help people achieve the best sound from their systems.
 
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