Linear Tracking versus Pivoted Tonearms: A discussion

[Atmasphere]

Skating force does not reverse direction anywhere on the record surface including two null points when using an overhung tonearm. In contrast, on underhung arms, the skating force does reverse direction after the single null point.

Almost all pivoted tonearms are overhung — only a handful are underhung. That’s an absolute fact. Anything you or anyone else says to dispute it will only demonstrate a lack of understanding.

Apparently the Triplanar is underhung.

 

[mtemur]

A few more words about the tangential tonearm, because most of you have never dealt with it. It has two advantages that are insurmountable for rotary tonearms:

- the first is the tangential error towards the end, especially towards the mark of recorded LPs. The distortion in this part increases disturbingly audibly with 9-inch and even 12-inch tonearm. And that is where songs end with pompous endings in classical music. You can partially defend yourself with very long tonearm !!!, but you can also give up on such records. Crying or Very sad

- the second is - in my opinion, much more important than the first - the absence of problems with slipping - you don't need anti-slip.
Of course, we can reduce (so that this doesn't erode us psychologically) by saying that this is not audible. Of course, you can not hear this on the same tonearm that has this problem, because the trick is not only in the exact dose of anti-slip, but in the fact that it cripples the output dose.
I will start with the force dosing - the problem of the anti-slip force cannot be solved even theoretically !!!, because it is tied to the modulation of the record, which is constantly changing.

More importantly - the sliding force, which pulls the tonarm inward, acts on the needle. The anti-slip force acts on the tonear . Between the needle and the tonarm there is a soft damper, which allows the needle to follow the modulations of the groove.
So the needle and its damper are under a constant one-sided lateral load. Which is constantly changing and, in addition, changes the tangential error at the moment (due to the deflection of the needle), so it must be set to some average modulation value.
In measurements, the distortion curves are strongly asymmetric between the left and right channels, as well as intermodulation and channel separation.
In addition, the consequences on 'soft' heads are already visible to the eye, and with high coherence (usually MM), over time the needle protrudes strongly to the side, inward. Because the damper is permanently deformed. On hard MCs this is less, but still.
With the tangential tonearm this is not there, which is felt as a relief when listening, a certain relaxation in the sound and listening towards the end of the LP in general becomes a pleasure - a real relief after decades of turning the tonearm of all possible manufacturers, when the fear of how the anxiety will increase towards the end of the LP creeps under your skin.

The belief is that a higher circumferential speed at the beginning gives a better result. But I have seen measurements of the mechanical noise of the record (unmodulated grooves), which decreases as the end of the LP approaches. So a better signal/noise of the needle sliding due to the lower speed towards the end!! The curve shows a difference of about 2.5 dB at 1 kHz, which increases continuously and reaches about 5 dB above 14 kHz. The tangential lever allows you to hear this clearly, because it is not covered by distortion due to the tangential error, wow.

It was translated with a translator, I hope it is understandable.

p.s. long tonearm is a new story though

In a linear-tracking tonearm, the entire arm and bearing assembly move together with the cantilever and stylus from the outer to the inner grooves. As a result, the cantilever and coil assembly apply uneven pressure on the damper — compressing the inner side while releasing the outer. This creates a significant force, much higher than in pivoted tonearms, since pivoted designs don’t carry the entire assembly; they simply rotate the arm tube. This uneven stress is one of the main reasons many linear trackers sound lifeless, uninvolving, and technically inferior compared to good pivoted designs.

Another issue with linear trackers is rigidity. Because the entire arm and bearing assembly must move and they’re lifted on the air during operation, they can’t achieve the same structural solidity or low-end authority as their pivoted counterparts.

By the way, the skating force doesn’t pull the “needle” (cantilever and stylus) inward. It actually skews the cantilever outward. That’s a basic concept — a good place to start learning.

 

[Deaconblues]

Skating force does not reverse direction anywhere on the record surface including two null points when using an overhung tonearm. In contrast, on underhung arms, the skating force does reverse direction after the single null point.

Almost all pivoted tonearms are overhung — only a handful are underhung. That’s an absolute fact. Anything you or anyone else says to dispute it will only demonstrate a lack of understanding.

Yep, the Dual 1219 is overhung from the factory. Almost no overhang when the cartridge is moved further back inside the headshell. Noticeable reduction in skating when aligned this way.

 

[mtemur]

Apparently the Triplanar is underhung.

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.

 

[Atmasphere]

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.

I'm using the 9" arm. When placed on a spinning blank disk, whether at the outside or near the runout groove area, it will move (skate) to near the center of the LP's playing surface.

In a linear-tracking tonearm, the entire arm and bearing assembly move together with the cantilever and stylus from the outer to the inner grooves. As a result, the cantilever and coil assembly apply uneven pressure on the damper — compressing the inner side while releasing the outer. This creates a significant force, much higher than in pivoted tonearms, since pivoted designs don’t carry the entire assembly; they simply rotate the arm tube. This uneven stress is one of the main reasons many linear trackers sound lifeless, uninvolving, and technically inferior compared to good pivoted designs.

Another issue with linear trackers is rigidity. Because the entire arm and bearing assembly must move and they’re lifted on the air during operation, they can’t achieve the same structural solidity or low-end authority as their pivoted counterparts.

By the way, the skating force doesn’t pull the “needle” (cantilever and stylus) inward. It actually skews the cantilever outward. That’s a basic concept — a good place to start learning.

The Rabco didn't behave this way, since it had a full gimbal that was mounted to the linear track. This allowed the arm to move in any direction although it was limited.

Such an arm would be unable to play some of the novelty LPs that start near the runout grooves and move outwards.

 

[mtemur]

I'm using the 9" arm. When placed on a spinning blank disk, whether at the outside or near the runout groove area, it will move (skate) to near the center of the LP's playing surface.

The Rabco didn't behave this way, since it had a full gimbal that was mounted to the linear track. This allowed the arm to move in any direction although it was limited.

Such an arm would be unable to play some of the novelty LPs that start near the runout grooves and move outwards.

I highly recommend checking that the P2S distance and overhang are in line with the specified values, then try again.

 

[Atmasphere]

I highly recommend checking that the P2S distance and overhang are in line with the specified values, then try again.

It is set up according to the included protractor; verified with the MoFi protractor. It was also examined by the owner of Triplanar. I've seen him set up that arm many times at shows.

 

[J.R. Boisclair]

I'm using the 9" arm. When placed on a spinning blank disk, whether at the outside or near the runout groove area, it will move (skate) to near the center of the LP's playing surface.

Sounds like internal torque forces to me. Easily measurable. Your damper is very likely crying out for mercy. Relieve that force and you will hear the improvement immediately

 

[Atmasphere]

Sounds like internal torque forces to me. Easily measurable. Your damper is very likely crying out for mercy. Relieve that force and you will hear the improvement immediately

Damper? The arm is equipped with a damping trough but I've never used it. There is no other obvious damping mechanism on the arm. If you are referring to the cantilever suspension that seems to hold up quite well. Cartridges are very long-lived on it; I've only had two since it was purchased 19 years ago or so.

 

[mtemur]

@J.R. Boisclair I feel your pain — pretty sure you feel mine too.

 

[J.R. Boisclair]

Damper? The arm is equipped with a damping trough but I've never used it. There is no other obvious damping mechanism on the arm. If you are referring to the cantilever suspension that seems to hold up quite well. Cartridges are very long-lived on it; I've only had two since it was purchased 19 years ago or so.

Exactly - the motor damper. It's subject to a 6:1 or 7:1 lever arm by the torque forces which your comment suggests exist. If your arm behaves as you described, your cartridge performance is most certainly being debilitated.

 

[Atmasphere]

Exactly - the motor damper. It's subject to a 6:1 or 7:1 lever arm by the torque forces which your comment suggests exist. If your arm behaves as you described, your cartridge performance is most certainly being debilitated.

That certainly sounds like something to pay attention to. What would be the procedure (since it appears properly set up)?

 

[J.R. Boisclair]

Watch this and feel free to contact me via email, phone or WBF with any questions.

 

[Mike Lavigne]

Sounds like internal torque forces to me. Easily measurable. Your damper is very likely crying out for mercy. Relieve that force and you will hear the improvement immediately

Joel Durand used my Wally Skater v2.2 to fine tune my Durand Tosca L.E. and the change was profound while subtle. the music was freed up. if i did not hear it i would never have expected it.

 

[Atmasphere]

Watch this and feel free to contact me via email, phone or WBF with any questions.

Thanks for that. As far as I can make out, our cartridge does not have a coil damper (Grado Statement). The Triplanar does not allow you to not apply zero anti-skate. The arm is set up right now to apply as little as possible so there is always some present. My surmise is the internal wire is the source of the arm's behavior. At any rate its never mistracked with anything we've thrown at it. Its always been smooth and well-behaved.

I'm always open to improving performance but it sounds like this arm would have to go back to Triplanar to be properly sorted, if my surmise is correct.

 

[J.R. Boisclair]

Thanks for that. As far as I can make out, our cartridge does not have a coil damper (Grado Statement). The Triplanar does not allow you to not apply zero anti-skate. The arm is set up right now to apply as little as possible so there is always some present. My surmise is the internal wire is the source of the arm's behavior. At any rate its never mistracked with anything we've thrown at it. Its always been smooth and well-behaved.

I'm always open to improving performance but it sounds like this arm would have to go back to Triplanar to be properly sorted, if my surmise is correct.

Based on your description of the issue, I think you are probably correct. Measure with a WallySkater and you can quantify the issue.

 

[microstrip]

I'm using the 9" arm. When placed on a spinning blank disk, whether at the outside or near the runout groove area, it will move (skate) to near the center of the LP's playing surface. (...)

In order to check for tonearm friction or forces I stick a small magnet (around 10g) with the NS perpendicular to tonearm and I use a large coil (5 cm diameter) placed about 10 cm from the magnet. Applying variable DC currents with a source to the coil placed at symmetrical points we can determine the threshold due to friction and tonearm non symmetries.

Surely the tonearm must be balanced for the horizontal position - no down force and all I could get were mostly comparative friction torques, not absolute values. SME's and Graham were great, Helius Orion not so much.

 

[tony22]

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

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

 

[Salectric]

Thanks for that. As far as I can make out, our cartridge does not have a coil damper (Grado Statement). The Triplanar does not allow you to not apply zero anti-skate. The arm is set up right now to apply as little as possible so there is always some present. My surmise is the internal wire is the source of the arm's behavior. At any rate its never mistracked with anything we've thrown at it. Its always been smooth and well-behaved.

I'm always open to improving performance but it sounds like this arm would have to go back to Triplanar to be properly sorted, if my surmise is correct.

Ralph, you can disable the AS on your Triplanar by pushing the little black lever all the way up. This way it never touches the AS mechanism as the arm crosses the record. I have done this with each record I’ve played with the Triplanar for the last 20 years. It becomes second nature.

 

[PeterA]

Skating force does not reverse direction anywhere on the record surface including two null points when using an overhung tonearm. In contrast, on underhung arms, the skating force does reverse direction after the single null point.

Almost all pivoted tonearms are overhung — only a handful are underhung. That’s an absolute fact. Anything you or anyone else says to dispute it will only demonstrate a lack of understanding.

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.