Sliding force???

[ack]

It's a beautiful Sunday for a deep-dive into the subject. So here's a paper on the math of skating https://drive.google.com/file/d/11saMtnPRpj8xZ-M_CGDhgbPbVfufSDV1/view linked to by AnalogMagik's coverage on the subject https://www.analogmagik.com/antiskate , and it appears their test LPs plus software (which measures distortion) is probably the best way to set this force; however, the whole thing costs $750 in the US. The paper also covers the solutions provided by some arms, and old skating force measurement devices, and the first patent on it dating back to 1931 from Bell Labs.

Excerpts:

<<As the turntable spins, the cartridge stylus of pivoted tonearms may experience uneven pressures on the groove walls, a side-thrust which makes the stylus lean harder against one side of the groove than the other. This side-thrust - normally compensated by an anti-skating adjustment - is caused by the offset angle for headshell, groove modulation, and other factors. If there is no compensation for the skating force, the distribution on the vertical tracking force on the groove walls is increased in the Left Channel (Inner Groove Walls, resulting in distortion in the Right Channel, and vice versa.>>

<<
The effects of Antis-kating is dependent on many factors:

Mass of the armwand
Vertical Tracking Force
Cartridge suspension
Stylus Shape
VTA/Azimuth/Alignment Geometry
Bearing chatter
Vinyl Materials
etc......
>>

<<On 12" tonearms tracking at 2g or above, you may notice a number where the L and R channel distortion is already very close, or you may observe that numbers do not correspond to anti-skating changes. In such cases, the anti-skating force is not required.

Some tonearm designs have inherent imbalances and will register numbers which will be skewed towards one channel, in such cases, nothing can be done. Some tonearms have too much anti-skating force even at the lowest setting, so the results are highly dependent upon equipment quality.>>

<<One must realize that the force exerted on the stylus is not linear, therefore the amount of anti-skating force required will be different depending on the relative location of the cartridge towards the record spindle. The curve is somewhat of a parabolic shape, with the skating force higher at the outer groove than at the inner groove, and lowest in the middle. Some tonearms designs have a mechanism which will increase anti-skating force gradually to counteract the non-linear nature of the centripetal force.

Optimizing anti-skating adjustment at the outer grooves where the skating force is the strongest will cause over-compensation across the inner groves. This is why the anti-skating track is placed near the inner grooves. >>

<<Anti-skating affects crosstalk measurements. We have observed that when anti-skating is set incorrectly, the imbalance will sometimes (but not always) cause crosstalk readings to be skewed so that in an optimal number can never be achieved. Therefore it is important to go back and forth between Anti-skating and Azimuth, as well as VTF and VTA to achieve an optimal set of numbers.

Again, we emphasize that no setup parameter can be optimized in isolation. >>




If a skating force is generated a different vector diagram is R* formed, with Fv + Fs as resulting vector. This resulting vector can R L be resolved into vectors R* and L*, with R* being shorter than L*.

<<The reaction force (to the friction force) of the tone arm passes through the arm pivot. These two forces combine as vectors and, because of the angle ? between groove tangent and effective length L, leave an unbalanced force, the skating force Fs. This force is at right angles to the groove tangent and tends to pull the arm towards the record's centre (see fig. 1). In fig. 1 the stylus tip is on a null point, therefore the skating force is directed exactly towards the record centre. The skating force is determined by the magnitude of ?, which varies across the record surface (? = angle between groove tangent and effective arm length = offset angle ? + tracking error ?, with ? varying across the record surface, (see fig. 10)),the cartridge’s mechanical resistance (cantilever damping). In fig.1 the angle ? is equal to the offset angle ?.>>

<<Skating force compensation enhances trackability by about 20-25 %.>>

[ack: This is very much in line with the out-of-phase test using my Ultimate Test LP that I posted earlier, where cancellation in mono improved from -8dB without anti-skating to -10dB with]

<<Higher modulation velocities result in increased skating force [1, 2]. Wright [6] could show experimentally
that the friction force increased for higher modulation velocities (for sinewaves).>>

<<The skating force Fs is a function of groove radius R, overhang D and effective arm length L>>

<<
Final remarks:

Since skating force is not constant across the record surface but describes a somewhat parabolic curve exact compensation is not possible: whatever the precision of setting the antiskating , the curve of the skating force will be intersected in two points at best.

From discussions on web forums it becomes evident that some people think that skating force is zero when the tracking error is equal to zero, as it is the case in the null points. This is true only for linear tracking arms, for pivoted arms this simply not correct. As long as the line connecting the stylus tip to the arm pivot is not tangential to the groove at the contact point, which is always the case for pivoted arms, a skating force is generated. For that very reason tangential pivoted arms like the Garrard Zero and the Thales still have anti-skating mechanisms.>>

 

[microstrip]

It's a beautiful Sunday for a deep-dive into the subject. So here's a paper on the math of skating https://drive.google.com/file/d/11saMtnPRpj8xZ-M_CGDhgbPbVfufSDV1/view linked to by AnalogMagik's coverage on the subject https://www.analogmagik.com/antiskate , and it appears their test LPs plus software (which measures distortion) is probably the best way to set this force; however, the whole thing costs $750 in the US. The paper also covers the solutions provided by some arms, and old skating force measurement devices, and the first patent on it dating back to 1931 from Bell Labs. (...)

You can easily measure distortion using a decent sound card - I do it regularly - the main question is knowing at what absolute level and conditions antiskating should be tested and optimized. Unfortunately my previous question got no answer ... I have test several test LPs with levels between 2 and 18 dB in 2-3 dB steps but I am not sure what I should use.

Unless we can quantify the problem every result is tonearm and cartridge dependent and results are not transferable. I am now joining efforts with two other local audiophiles who own good turntables to order the AnalogMagik system.

 

[ack]

You can easily measure distortion using a decent sound card - I do it regularly - the main question is knowing at what absolute level and conditions antiskating should be tested and optimized. Unfortunately my previous question got no answer ...

Unless we can quantify the problem every result is tonearm and cartridge dependent and results are not transferable. I am now joining efforts with two other local audiophiles who own good turntables to order the AnalogMagik system.

Agreed that results are not transferable. The AnalogMagik LPs, set of tests and software appear to be the ultimate set-up system. I also found their videos quite informative, though they largely repeat the written text.

In the PDF, it's also interesting to read about Namiki's patent (Namiki being one of the two stylus manufacturers, the other being Ogura) on a anti-skating measuring device.

Finally, again, VPI's assertions that all arms they tested sound better w/o anti-skating are just sheer nonsense; and if the math is not enough proof for them, the proof is in my room. I am currently playing RR's Nojima Plays Ravel and the results are ravishing.

 

[ack]

I am loving this AnalogMagik; they also use the correct language and measurements for VTA/SRA, i.e. IMD:

The AnalogMagik software has a VTA function which allows you to determine the actual intermodulation distortion number and it will be displayed on the laptop screen. Simply fine tune adjust the VTA angle until you reach a level which produces the lowest intermodulation distortion percentage (IMD%).

3) In cases where the resonance frequency of the arm/cartridge combo doesn't fall within the range of 8-12Hz, IMD% usually gives out bad numbers.

 

[jadis]

Finally, again, VPI's assertions that all arms they tested sound better w/o anti-skating are just sheer nonsense; and if the math is not enough proof for them, the proof is in my room. I am currently playing RR's Nojima Plays Ravel and the results are ravishing.

I've been chatting with a local hobbying with a 10” JMW Memorial 3D arm with VTA-on-the-fly. According him, without AS, the inner grooves play with distortion. He tried all the AS settings as per Mat Weisfeld suggestions but still didn’t like what he heard with the inner tracks. He said that even with anti-skate on, the sound of his Prime/3D arm wasn’t as relaxed and smooth at all when compared with his current Project Xtension 10 table and arm which he also applied some AS force. So, it can be said really that VPI's no AS claim is not accurate.

 

[ack]

I've been chatting with a local hobbying with a 10” JMW Memorial 3D arm with VTA-on-the-fly. According him, without AS, the inner grooves play with distortion. He tried all the AS settings as per Mat Weisfeld suggestions but still didn’t like what he heard with the inner tracks. He said that even with anti-skate on, the sound of his Prime/3D arm wasn’t as relaxed and smooth at all when compared with his current Project Xtension 10 table and arm which he also applied some AS force. So, it can be said really that VPI's no AS claim is not accurate.

That's because he has not installed my magnetic stabilizing solution I played the Mahler 2nd finale on LP today, and it was with no distortion, for the first time - a digital Philips recording of the BSO with Ozawa. Simply spectacular.

 

[jadis]

That's because he has not installed my magnetic stabilizing solution

Well, he moved on already to another rig. He said Mat W replace his arm with a new one but by that time he already bought a new ProJect rig.

So I guess it's rig to rig dependent, this AS thing. I never thought it would be quite complex and I now suspect 'numerical values' on AS dials differ from arm to arm even. I'm trying to find some pictures of the innards of these AS 'springs' and if not that will be my first question to the Linn tech man if he visits our country.

 

[jadis]

Yes, very good - this is a traditional approach, it is simple and it does work.

Watch the cantilever from the front of the cartridge when the stylus is lowered into the groove about an inch into a spinning record. If the cantilever deflects to the right, increase the anti-skate and likewise if it deflects to the left, then reduce anti-skate. It's pretty easy to see. You can check at various locations on the record as anti-skate is not consistent across the entire LP.

Well, I just found out that right now, with 0 AS bias, the first few minutes of the first cut has a teeny weeny bit of deflection to the right, then miraculously disappears on about the second track while tracking straight down and from there onward, continues to track straight till the end of the record. And, I have decided to increase the tracking force from 1.80g (which is the minimum) to 1.90g (max recommended is 2.0g) and the lean-ness that I initially reported is now a bit improved - more body to everything. Boy, I never had this experience with the Rega arm.

 

[ack]

Nice! Meantime, I'll need to wait a few weeks to get my damaged A90 back, before I continue with my experimentations - bad day yesterday afternoon.

 

[jadis]

Nice! Meantime, I'll need to wait a few weeks to get my damaged A90 back, before I continue with my experimentations - bad day yesterday afternoon.

Oh, sorry to hear that. Accident?

 

[ack]

Oh, sorry to hear that. Accident?

Yeah, cart was on the VTF scale and I accidentally yanked the scale, taking out the cantilever.

 

[jadis]

And more craziness. Right after I increased the tracking force to1.90, I felt a little congestion in the sound stage, not believing what I heard, I put it back to 1.80g and just like that, the sound became more open again. Now I'm feeling either my eyes or my ears are playing tricks on me.

 

[jadis]

Yeah, cart was on the VTF scale and I accidentally yanked the scale, taking out the cantilever.

Ouch.

 

[ack]

I am feeling stupid, but at the same time it was probably due for re-tipping after 10 or so years. I’ll get a brand new motor.

 

[tima]

Well, I just found out that right now, with 0 AS bias, the first few minutes of the first cut has a teeny weeny bit of deflection to the right, then miraculously disappears on about the second track while tracking straight down and from there onward, continues to track straight till the end of the record. And, I have decided to increase the tracking force from 1.80g (which is the minimum) to 1.90g (max recommended is 2.0g) and the lean-ness that I initially reported is now a bit improved - more body to everything. Boy, I never had this experience with the Rega arm.

What I find encouraging in yr report is the correlation between what you hear and the physical changes you made. While I'm generally pro instrumentation I'm still of a mind that our ears are our most sensitive instrument - and we should believe them.

 

[microstrip]

What I find encouraging in yr report is the correlation between what you hear and the physical changes you made. While I'm generally pro instrumentation I'm still of a mind that our ears are our most sensitive instrument - and we should believe them.

IMHO the ear is not more sensitive than instruments in this case - simply we do not know exactly how to correlate what we measure with the best subjective sound quality. Small changes in bias result in significant changes in the spectra of distortion.

But yes we should believe our ears - vinyl playback is mostly tuned to our preference. It is why we have such conflicting advices on tuning. BTW, the main reason I would like to adjust bias with instruments is that when adjusting with music my choices depend on the recording - some tracks seem to need more bias than others - and need a long time. I can't consider doing it for all the tonearms and cartridge combinations I use.

 

[tima]

IMHO the ear is not more sensitive than instruments in this case - simply we do not know exactly how to correlate what we measure with the best subjective sound quality. Small changes in bias result in significant changes in the spectra of distortion.

But yes we should believe our ears - vinyl playback is mostly tuned to our preference. It is why we have such conflicting advices on tuning. BTW, the main reason I would like to adjust bias with instruments is that when adjusting with music my choices depend on the recording - some tracks seem to need more bias than others - and need a long time. I can't consider doing it for all the tonearms and cartridge combinations I use.

Well, okay... Who are you going to believe - your lying eyes or your lying ears?

I'm aware of two explicit anti-skating 'measurement devices':

One is AnalogMagik. With your table's output hooked into a sound card and computer, play a test track. Get two numbers. Try to bring the numbers close to one another by adjusting anti-skate. Iirc we both have AM.

The other is the Wally Skater from Wally Malewicz (rip) - the best cartridge/tonearm/setup engineer / guru that I ever met. That product is long gone. It was analog based and made no electrical measurement. It's measurement is in percentages of VTF. I'll attach Wally's instructions so you can get some idea.

Suppose you set your antiskate based on one of these tools (or another acceptable tool if you know of one) and your ears tell you a different setting is audibly / sonically preferable. It's just as easy to argue that the measurement based setting does not reflect the sensitivity of your ears as it is to argue the measurement is more sensitive than your ears and it is correct. I grant you noted "IMHO" in your claim that the ear is less sensitive. I agree the correlation (or lack therof) is relevant. And I agree there may be correlation between anti-skate and azimuth and that one may throw-off readings for the other.

As noted I take a reactive approach to anti-skate. Audible distortion in one channel - it can range from a high-frequency buzzing sound to stuttering like break up - is for me the prompt to address it. Typically, if you cannot "fix it" with anti-skate adjustment, and your azimuth is satisfactory (or 'measures well') then it's likely a problem with the cartridge or the cartridge/tonearm match. It could be other things such as VTF, but from experience, not all cartridges provide adequate anti-skate function (or mid-groove stability) even when otherwise set up properly. But it's fairly uncommon to encouter that - ime. Compliance (or poor/broken suspension) and/or poor stylus attachment to the cantilever may be culprits.

I do appreciate your participation in this.

 

[microstrip]

Well, okay... Who are you going to believe - your lying eyes or your lying ears?

I'm aware of two explicit anti-skating 'measurement devices':

One is AnalogMagik. With your table's output hooked into a sound card and computer, play a test track. Get two numbers. Try to bring the numbers close to one another by adjusting anti-skate. Iirc we both have AM.

The other is the Wally Skater from Wally Malewicz (rip) - the best cartridge/tonearm/setup engineer / guru that I ever met. That product is long gone. It was analog based and made no electrical measurement. It's measurement is in percentages of VTF. I'll attach Wally's instructions so you can get some idea.

Suppose you set your antiskate based on one of these tools (or another acceptable tool if you know of one) and your ears tell you a different setting is audibly / sonically preferable. It's just as easy to argue that the measurement based setting does not reflect the sensitivity of your ears as it is to argue the measurement is more sensitive than your ears and it is correct. I grant you noted "IMHO" in your claim that the ear is less sensitive. I agree the correlation (or lack therof) is relevant. And I agree there may be correlation between anti-skate and azimuth and that one may throw-off readings for the other.

As noted I take a reactive approach to anti-skate. Audible distortion in one channel - it can range from a high-frequency buzzing sound to stuttering like break up - is for me the prompt to address it. Typically, if you cannot "fix it" with anti-skate adjustment, and your azimuth is satisfactory (or 'measures well') then it's likely a problem with the cartridge or the cartridge/tonearm match. It could be other things such as VTF, but from experience, not all cartridges provide adequate anti-skate function (or mid-groove stability) even when otherwise set up properly. But it's fairly uncommon to encouter that - ime. Compliance (or poor/broken suspension) and/or poor stylus attachment to the cantilever may be culprits.

I do appreciate your participation in this.

Thanks for a very interesting alternative - it will need some time to fully appreciate the paper and find the diagrams. I remember the suspended Wallyskater but I have to check the basics behind it. Just a fast question - did Wally Malewicz method use a common music LP or a test LP?

 

[tima]

Thanks for a very interesting alternative - it will need some time to fully appreciate the paper and find the diagrams. I remember the suspended Wallyskater but I have to check the basics behind it. Just a fast question - did Wally Malewicz method use a common music LP or a test LP?

The full Wally Analog Shop toolkit included a Cardas Frequency Sweep and Burn-in record. I know that was used as part of azimuth measurement and his WallySpeed calibration. For the WallySkater *I think* no record was required, but it was probably a good idea to have a record (old unwanted) on the platter when using it. Some of his stuff goes back to circa 2003 or earlier. I still use the WallyVTA gauge today.

 

[jadis]

Well, a guy like me, I am not that technical inclined in these things, as my ET2 was installed and set up by a very capable tech man/dealer, and it lasted me for 20 something years that I never even bothered to read much about AS or azimuth. But indeed there was need for azimuth adjustment in the ET2 each time you change a cartridge, and I did that often while being a distributor of Koetsu - I had to play test for a few minutes each new arrival model to make sure they are not DOA. And guess what, through all those times, I just used my eyes to look down at the oval slot to see of the small azimuth controlling bolt is 'equal' to both its sides. And guess what, I never heard any distortions of mistracking or imbalance, even till I had to put on my own Rosewood Signature to use for the next 7 years. And the absence of azimuth adjustment in my old Rega and now Linn Akito just makes me resign to the fact that the arm maker assumes your cart maker knows how to level the top of the body and for the cantilever to fall down straight. And good it they do. And with this Koetsu Urushi I just bought last March, I noticed on day 1 that the base of the body, when viewed from the front is sloping a little down from right to left. Talking to my regional distributor about this, he said Koetsu aligns the cantilever regardless of the imperfections of the wood body, therefore, I can rest still and believe that the cantilever is properly set perfectly in terms of geometry, just by looking at how straight it is when it tracks vertically down with a spinning record. The slanting body is just a physical distraction. Things can get complicated as it goes on. That is part of the hobby.