Linear Tracking versus Pivoted Tonearms: A discussion

[J.R. Boisclair]

That is interesting. Thank you. I will admit to some lack of understanding. Could you please explain what makes one tone arm under hung and the other over hung? Is it whether or not the pivot point is above or below the record surface? Or does it have to do with the center of gravity being above or below the record surface? Or is it something else?

Edit: I think I just learned it is horizontal alignment, and whether the stylus goes beyond the spindle or falls short of it. The effective length versus the pivot to spindle distance.

The answer to that question is here:
Sound Bite Series: Skating Force

Sound Bite Series: Skating Force

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[PeterA]

Absolutely not. 12” version of Triplanar arm has 13.2 mm overhang, 17,6 degrees offset and conforms to Baerwald geometry.

However one of the few examples like ViV Lab Rigid Float is an underhang arm ignoring skating force at all.

BTW you can turn an overhung arm into an underhung arm by significantly altering P2S distance or vice versa.

That is interesting. You and I briefly discussed my new DST replica cartridge. When I don’t use the extra 20 mm metal adapter to rotate the cartridge pins but instead use a tiny tiny disk, I am essentially moving the stylus back in the head shell or reducing the pivot to stylist distance. There is still overhang, but much less. I can still use my two point protractor for alignment, but I am finding that I do not need much anti-skate force for good sound. The tracking force is very high, but I am finding that I use about 1/6 of the tracking force for anti-skate, at least according to my SME 3012R anti-skate scale. Perhaps the shorter pivot to stylist distance is a reason for this.

 

[PeterA]

The answer to that question is here:
Sound Bite Series: Skating Force

Sound Bite Series: Skating Force

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Thank you J. R. I have watched a few of these. I saw that in one, perhaps the 9" v. 12" arms, #2, that you recommend an anti-skate value of 10% of VTF. May I ask how you arrived at that value? I always set mine by listening, and I find that a low setting, usually between 15-20% works well. I have seen others recommend as much as 2/3 value of VTF up to equal the VTF. I always found those settings too high.

EDIT: Just finished the series, in order. Very informative and clear. Good work, J.R.

 

[J.R. Boisclair]

Thank you J. R. I have watched a few of these. I saw that in one, perhaps the 9" v. 12" arms, #2, that you recommend an anti-skate value of 10% of VTF. May I ask how you arrived at that value? I always set mine by listening, and I find that a low setting, usually between 15-20% works well. I have seen others recommend as much as 2/3 value of VTF up to equal the VTF. I always found those settings too high.

How would you know you are at 15% to 20%??

If you are referring to the AS dials on tonearms that have 0 thru 3 or 4, those dials are at 1:10 ratio! If you are reading the dial, how do you know how much internal torque force your arm has and in which direction? How do you know your bearing’s static friction? These all should and can be measured in order to ensure optimum damper compression and to unknowingly avoid misaligning the cantilever at the null points

The research on the % of your VTF to apply as AS was done well many years ago. It does vary a bit by what alignment scheme you choose but not by terribly much. Recently Miguel Barrio used his PhD chops to measure it came up with 11% but I am guessing he was measuring at the outer area of the platter where skating is at its highest

 

[thekong]

That is interesting. You and I briefly discussed my new DST replica cartridge. When I don’t use the extra 20 mm metal adapter to rotate the cartridge pins but instead use a tiny tiny disk, I am essentially moving the stylus back in the head shell or reducing the pivot to stylist distance. There is still overhang, but much less. I can still use my two point protractor for alignment, but I am finding that I do not need much anti-skate force for good sound. The tracking force is very high, but I am finding that I use about 1/6 of the tracking force for anti-skate, at least according to my SME 3012R anti-skate scale. Perhaps the shorter pivot to stylist distance is a reason for this.

Hi Peter, I am not familiar with the 3012R, but since you have shortened the pivot to stylist distance, would the same two point protractor applied? Are the protractors for the 3009R and 3010R exactly the same as the one for 3012R ?

 

[PeterA]

How would you know you are at 15% to 20%??

If you are referring to the AS dials on tonearms that have 0 thru 3 or 4, those dials are at 1:10 ratio! If you are reading the dial, how do you know how much internal torque force your arm has and in which direction? How do you know your bearing’s static friction? These all should and can be measured in order to ensure optimum damper compression and to unknowingly avoid misaligning the cantilever at the null points

The research on the % of your VTF to apply as AS was done well many years ago. It does vary a bit by what alignment scheme you choose but not by terribly much. Recently Miguel Barrio used his PhD chops to measure it came up with 11% but I am guessing he was measuring at the outer area of the platter where skating is at its highest

I did not know about the 1:10 ratio on those dials. Thank you. That would suggest that you set the number on the dial equal to the VTF. Perhaps the scale on the 3012R is the same.

I suppose only your device can confirm the actual percentages. And I do not know how much internal torque force my arm has or in what direction, or how much static friction by bearings have. There is a lateral balance mechanism on my SME 3012R arm though. When it is vertically balanced and floating just above the surface of the LP, one can push the arm slightly to see if it drifts in toward the spindle or out and check across different points of the LP. If it drifts, one can adjust the arm to reduce or eliminate the drift. I assume this gets close to zero internal torque force or improves lateral balance so that it floats without drift. How smoothy it glides in either direction might be an indication of bearing static friction.

I use a calibrated scale to measure VTF, and then the anti-skate scale on my SME 3012R arm. The tonearm manual describes the values on the scale. I should reread the manual to see if it is also a 1:10 ratio. I do not have your device to confirm. I watched a couple of your WallySkate videos to see how you use it. It is a useful looking device and I am sure it works well and as designed.

 

[PeterA]

Hi Peter, I am not familiar with the 3012R, but since you have shortened the pivot to stylist distance, would the same two point protractor applied? Are the protractors for the 3009R and 3010R exactly the same as the one for 3012R ?

My protractor works for slightly different length cartridges as seen in the range on the jig in the photo. All within this range work with this protractor and the SME 3012R arm. I do use the same two point protractor for all of the cartridges in my 12" arm. I measure the collar to stylus tip and do the alignment with the jig in the photo. It is not an SME protractor but is recommended for this arm. I do not know if the protractor can be used for the shorter SME arms, but I do not think so. The beauty of the jig is that it has very straight sides so it is very easy to get the alignment accurate and I can do it without risking damage to the cartridge. It also words well for cartridges that have very difficult to see cantilevers and styli, like my Neuman DST Replica.

 

[thekong]

My protractor works for slightly different length cartridges as seen in the range on the jig in the photo. All within this range work with this protractor and the SME 3012R arm. I do use the same two point protractor for all of the cartridges in my 12" arm. I measure the collar to stylus tip and do the alignment with the jig in the photo. It is not an SME protractor but is recommended for this arm. I do not know if the protractor can be used for the shorter SME arms, but I do not think so. The beauty of the jig is that it has very straight sides so it is very easy to get the alignment accurate and I can do it without risking damage to the cartridge. It also words well for cartridges that have very difficult to see cantilevers and styli, like my Neuman DST Replica.

View attachment 159839

I asked because as I understand, tonearms in the same series but with different lengths, such as the Kuzma 4Point and 4Point14, may have different offset angles, so the 4Point headshell cannot be used with the 4Point14 and vice versa! As such, I am wondering whether the 3009R, 3010R and 3012R all share the same offset angle, and whether the same protractor could apply when you are basically converting a 3012R into something like a 3011R !

I don’t have the answer, just wanting to learn!

 

[PeterA]

I asked because as I understand, tonearms in the same series but with different lengths, such as the Kuzma 4Point and 4Point14, may have different offset angles, so the 4Point headshell cannot be used with the 4Point14 and vice versa! As such, I am wondering whether the 3009R, 3010R and 3012R all share the same offset angle, and whether the same protractor could apply when you are basically converting a 3012R into something like a 3011R !

I don’t have the answer, just wanting to learn!

Ok. I know the SME arms of different lengths have different offset angles. Less offset the longer the arm which is why the skating force is less with longer arms, or at least part of the reason.

You can just look up the various effective lengths and offset angles of the SME arms.

 

[J.R. Boisclair]

…which is why the skating force is less with longer arms, or at least part of the reason.

I used to think this as well but it is not true. Watch the series I referred to above to see why.

 

[mtemur]

That is interesting. You and I briefly discussed my new DST replica cartridge. When I don’t use the extra 20 mm metal adapter to rotate the cartridge pins but instead use a tiny tiny disk, I am essentially moving the stylus back in the head shell or reducing the pivot to stylist distance. There is still overhang, but much less. I can still use my two point protractor for alignment, but I am finding that I do not need much anti-skate force for good sound. The tracking force is very high, but I am finding that I use about 1/6 of the tracking force for anti-skate, at least according to my SME 3012R anti-skate scale. Perhaps the shorter pivot to stylist distance is a reason for this.

You’re not changing P2S distance but changing effective length by changing overhang. Reduced overhang requires less anti-skating.

 

[tima]

I asked because as I understand, tonearms in the same series but with different lengths, such as the Kuzma 4Point and 4Point14, may have different offset angles, so the 4Point headshell cannot be used with the 4Point14 and vice versa! As such, I am wondering whether the 3009R, 3010R and 3012R all share the same offset angle, and whether the same protractor could apply when you are basically converting a 3012R into something like a 3011R !

I don’t have the answer, just wanting to learn!

Yes, different tonearm lengths can have different offset angles. If you draw a line straight back from the stylus through the offset and on into space and draw a line from the stylus to the cartridge pivot point (effective length), the angluar difference between the lines measured at the offset point is the offset angle. At least as I understand it.



I believe you are correct that the headshells for the 4Point and the 4Point 14 are different because of the different offset angles of the arms.

Wrt protractors I think it depends on the protractor. For example: the original Wally protractor is specific to the effective length and is thus arm specific. The newer Wally Universal Protractor v2 supports multiple effective lengths. The db Systems protractor supports multiple arm lengths. The Acoustical Systems Uni-Protractor from Dieter Brakemeir supports different length arms but will have a separate mirrored insert for each arm.

 

[Deaconblues]

Yes, different tonearm lengths can have different offset angles. If you draw a line straight back from the stylus through the offset and on into space and draw a line from the stylus to the cartridge pivot point (effective length), the angluar difference between the lines measured at the offset point is the offset angle. At least as I understand it.

View attachment 159846

I believe you are correct that the headshells for the 4Point and the 4Point 14 are different because of the different offset angles of the arms.

Wrt protractors I think it depends on the protractor. For example: the original Wally protractor is specific to the effective length and is thus arm specific. The newer Wally Universal Protractor v2 supports multiple effective lengths. The db Systems protractor supports multiple arm lengths. The Acoustical Systems Uni-Protractor from Dieter Brakemeir supports different length arms but will have a separate mirrored insert for each arm.

I've experienced drastic reduction in apparent skating force by reducing the overhang of the cartridge in the headshell and applying a low-friction preservative coating to the record surface. The reduction of skating for reduced overhang is very apparent. I use a small fraction of the original antiskate calibration for the turntable (Dual 1219), and I think the sound is more open with less IGD.

 

[thekong]

Yes, different tonearm lengths can have different offset angles. If you draw a line straight back from the stylus through the offset and on into space and draw a line from the stylus to the cartridge pivot point (effective length), the angluar difference between the lines measured at the offset point is the offset angle. At least as I understand it.

View attachment 159846

I believe you are correct that the headshells for the 4Point and the 4Point 14 are different because of the different offset angles of the arms.

Wrt protractors I think it depends on the protractor. For example: the original Wally protractor is specific to the effective length and is thus arm specific. The newer Wally Universal Protractor v2 supports multiple effective lengths. The db Systems protractor supports multiple arm lengths. The Acoustical Systems Uni-Protractor from Dieter Brakemeir supports different length arms but will have a separate mirrored insert for each arm.

Yes, I understand there are universal protractors, like the Acoustical System, that support multiple effective lengths! But my question was specific to Peter’s setup. With the shortened effective length, but maintaining the same offset angle, could the same two point protractor still apply? Would you need to twist the cartridge a bit at the headshell to reach the correct zenith when the stylus hits that two null points ? Thanks

 

[mtemur]

Hmm, this intrigues me. Is there a link that explains how one might do this, and what the tradeoffs might be?

You can do it by mounting the arm in a different position so there’s no overhang, but the trade-offs are huge in my opinion. It’s like driving a car with a 5-speed transmission and only using 3 gears. I discussed it in more detail on the ViV Rigid Float thread and Klaudio’s pivoted linear arm thread.

 

[tima]

Yes, I understand there are universal protractors, like the Acoustical System, that support multiple effective lengths! But my question was specific to Peter’s setup. With the shortened effective length, but maintaining the same offset angle, could the same two point protractor still apply? Would you need to twist the cartridge a bit at the headshell to reach the correct zenith when the stylus hits that two null points ? Thanks

Yes to your first question. Peter and I use the db Systems protractor which is a two-point protractor and it accomodates arms of different effective lengths.

Wrt zenith. If you can actually see zenith error, I suppose you could try adjusting it and assess by listening. I think you need high-powered magnifiaction and high precision to do that. I've never tried it. As you may know, the SME 3009-3010-3012 headshell does not have slots but fixed holes, so there is very little room to adjust if at all.

 

[microstrip]

Yes, I understand there are universal protractors, like the Acoustical System, that support multiple effective lengths! But my question was specific to Peter’s setup. With the shortened effective length, but maintaining the same offset angle, could the same two point protractor still apply? Would you need to twist the cartridge a bit at the headshell to reach the correct zenith when the stylus hits that two null points ? Thanks

Good question - it depends on your approach to acceptable vinyl tracking error. SME is a fixed offset angle, fixed length arm with variable distance from pivot to platter spindle. It was originally supplied with a single point protractor - you would get zero tracking error at a fixed distance (around 66 mm , I think) and forget.

Using it with a double point protactor means you must find a point where the average errors at the two points is minimal - only by extreme chance you will get zero at both fixed points!

BTW, fixed offset angle tonearms are not acceptable for fans of tonearm alignment - the debates in the letters to editor in magazines between proponents of particular formulas in the 70's were as fierce as our current ones about vinyl versus digital - but we had to wait a couple of months between letters!

 

[J.R. Boisclair]

For any given alignment scheme – it doesn’t matter which one, just pick one (Baerwald, Loefgren, Stevenson) – if you change your overhang/effective length but do NOT change your pivot to spindle distance, then you can achieve tangency at one null point, but you will never get tangency at the second null point.

Likewise, if you reduce your overhang but maintain your P2S, you will reduce skating force, but this comes at the expense of proper alignment across the record surface as per the last sentence.

For any given alignment scheme, if you mess with the balance between overhang and P2S, no amount of changing your offset angle is going to improve things for you. You will only be offered the ability to be tangent to the groove at one location, not two.

 

[tony22]

Thanks @mtemur and @J.R. Boisclair. I'll just go by the book with my SMARTractor, all my Wally tools, and AM v1 and v2. But I'd sure like the full P.A.S. setup from Acoustical Systems!

 

[PeterA]

Yes, I understand there are universal protractors, like the Acoustical System, that support multiple effective lengths! But my question was specific to Peter’s setup. With the shortened effective length, but maintaining the same offset angle, could the same two point protractor still apply? Would you need to twist the cartridge a bit at the headshell to reach the correct zenith when the stylus hits that two null points ? Thanks

thekong, I simply use the same protractor moving the SME sled base forward to account for a slightly shortened effective length or backward to account for a slightly longer effective length. This changes the pivot to spindle distance. I still get alignment at the two null points with headshell edges (or my jig edges) parallel to the lines on the protractor. This suggests that zenith is correct at the two null points.

I start with the arm level. I can not adjust SRA or VTA at the headshell which would seem ideal, so I simple raise or lower the back of the arm. Once the arm height sounds right, I confirm or adjust slightly the horizontal alignment if needed again using the protractor. The whole process is straight forward and seems to work well.