Antiskating .... The last analog secret

Guys, the reason why skating forces are generated is that with an offset angle tonearm, there are two vectors involved. One is the drag of the LP groove pulling the cartridge stylus forward, and extends from the tonearm pivot through the cartridge stylus. The second vector is caused by the drag of the LP groove pulling the stylus forward but this time at the offset angle. When you sum these two vectors together (think back to high-school math), you generate a third vector which pulls the cartridge inwards, and it is this third vector that we refer to as the "skating force". The strength of this vector will depend directly on the drag from the LP groove and the angle of the offset.

So as long as you have a tonearm with an offset angle, skating forces will be generated. In other words, if you want to eliminate the skating forces (and the need to apply anti-skating, you have to get rid of the offset angle. Even if the stylus is aligned as well as possible within the geometry of the tonearm, skating forces will still be generated. No exceptions.

How the anti-skating compensation is accomplished obviously depends on the individual tonearm designer, and how well he understands his stuff. Depending on how competently their anti-skating mechanism works (or how well they can get it adjusted), some listeners may therefore prefer to avoid anti-skating. But please don't subsequently jump to the conclusion that a preference for no anti-skating with a particular tonearm means that it doesn't generate skating forces, or have a need to cancel such via an anti-skating mechanism. Because if the tonearm has an offset angle, skating forces will be generated. Again, no exceptions.

regards and hth, jonathan carr

Thanks for setting me straight on the vector analysis, Jonathan. So we do always have a skating force magnitude with angled tonearms. But that magnitude can vary with the magnitude of the force of the drag on the stylus and thus the needed AS compensation can vary. Perhaps I should take stltrain's stance and question my results further. But it is interesting that several of us have recently found less need for AS since improving on our cartridge alignment. Coincidence?

I had two ZYX cartridges (Fuji and Airy 3) that had the same 'needle out off axis' problem (see pictures above). Now I understand the AS was too high (2.0 on my SME4 corresponding to the requested VTF). Just installed my nex ZYX Atmos/D4 with zero AS, I hope this will avoid the 'out off axis syndrom'.

Renaat

Could you send a picture of the cartridge (with the "off axis" cantilever) Renaat?

Chris

Belated Merry Holidays to all. Just catching up on this fun and fascinating thread.

***

Hevac and Dgad both suggested - correctly - that the damage to Thomasheisig's cartridge could have resulted from sticky tonearm bearings. Most of the discussion is taking place amongst those with tonearms having very high quality bearings (JMW, Phantom, TriPlanar, Vector, etc.), but the danger of poor, dirty or poorly adjusted arm bearings should not be overlooked. That was a good alternative explanation.

Bearing drag on my OL Silver was notably higher than on my TriPlanar. The difference was easy to feel and the Silver, while a great performer at its price point, did not track or play nearly as well.

So we've developed another reason NOT to put very costly cartridges on lesser tonearms: besides not hearing all the cartridge is capable of, an inadequate arm may actually shorten the cartridge's lifespan. More support for Linn's original upgrade hierarchy: table, tonearm, cartridge.

***

Bearing drag and arm effective mass always provide some resistance to inward movement, so even arms lacking *any* AS device still apply "some" AS force. We can never actually get to zero AS.

This is true even of linear trackers, whose lateral effective mass resists the slow, inward spiralling of the groove. Those Mapleknoll/Walker/Rockport/Air Tangent guys need to add a PRO-skating device! Hah!

***

Based on suggestions above I took the next obvious step, which Dan apparently also just did: I removed the TriPlanar's AS mechanism altogether.

It isn't difficult and it's reversible. Just be careful when removing the little C-clip that it doesn't fly off somewhere. Once you slide the dogleg off, the post it rides on unthreads pretty easily.

The sonic improvements from removing the AS mechanism were about what we'd all predict: an increase in very low level information, soundstage deeper and improved in the back corners, etc. Not huge or even major, but audible.

As for tracking, most LP's played perfectly. On one stereo LP with powerful operatic vocals I got a tiny amount of L channel mistracking at one tough spot, then an equally tiny amount of R channel mistracking at another. ("Tiny" means a trace of HF fuzziness, not static-like bursts.)

Conclusion: my average AS setting (now as close to zero as possible) is okay but a trace more VTF was needed for those two passages on that LP, given that day's weather, etc. We need remote-controlled, adjustable, VTF-on-the-fly! ;-)

***

Yikes! No fluid damping trough. No AS mechanism. No arm rest/lock (in some cases). Our tonearms are disappearing!

I also considered removing the entire cueing mechanism. It's probably a significant resonator with all those fiddly bits and it looks like just two screws. This would be viable if you're comfortable cueing every LP by hand, which Paul isn't, so I didn't do it. Thom likes hand cueing so maybe he'll try. :-)

***

Playing just above minimal VTF and setting VTA/SRA for each record demonstrates the truth behind those notional charts in the white paper: that the sweet spot for these parameters is extremely tiny and the curve surrounding them can be very steep. I thought the paper and its charts offered a perspective that could be helpful/useful.