Linear tracking vs. Pivoted tracking tone arms.

I have also run linear trackers for years. I now run a Triplanar.

IMO, the Triplanar offers a lower tracking angle distortion than most linear trackers due to the fact that most linear trackers have far more lateral tracking mass than their vertical mass.

The cantilever of the cartridge is what the arm has to follow. If your tracking mass is extreme in the lateral mode, the cantilever will flex. If it does that, it becomes the source of the tracking error! If you run a cartridge that has low compliance so you can deal with this problem, the low compliance may be a problem in the vertical mode. The cantilever of the cartridge is quite short- so if you can see it flex at all then the tracking error is considerable.

So a radial tracking arm may well have a lower tracking error!

For this reason if a linear tracker is used, IMO it should be servo controlled rather than some sort of passive air bearing or the like. In this way the lateral and vertical tracking masses can be identical. To my understanding, there are no such arms made right now.

I've got to chime in here. I've been running a Trans-Fi Terminator low pressure air bearing tonearm that is affordable, simple to set up and sounds fantastic. Easily runs with my SME-V which I also love. The music flows so beautifully off the Terminator it is hard to describe. Just sounds so effortless.

Atmasphere,
Are you familiar with the ET2 arm? Its counterweight is decoupled in the horizontal plane which lowers its horizontal effective mass. I'm not sure if any other linear tracking arms have that feature.

Ketchup, I have heard that before. And you are right, that's a helpful feature and not found in the majority of air bearing arms.

What it does is react to minor perturbations (and is thus an acknowledgment of the issue), but if you think about it, for best results it would have to be tuned to anticipate the compliance of the cartridge (I suspect it introduces LF noise too, translating the subsonic noise generated by the bending of the stylus that otherwise happens to a higher frequency). All that mass is still moving across the LP though, and its all being moved by that stylus. IOW, its a compromise but better than nothing!

There is a different issue that all air bearing arms have. Ever notice that if you have higher pressure pumps, reservoirs and regulators that the arm sounds better? There is a basic engineering problem at play. In LP playback, there can be no play between the platter surface and the mounting of the cartridge. This issue is very much akin to the steering in an automobile. If there is play between the steering wheel and the wheels of the car moving on the road, the result will be uncertain handling and could be dangerous!

In a turntable this sort of play is translated as a coloration in the sound. Anyone with an air bearing arm knows what I am talking about- the pumps and stuff I mentioned earlier. IOW, there is play that is inherent in the arm and there is nothing that can be done about it if the arm is to work.

This is why I favor the servo-controlled approach. Its a pity that there are no arms that have been developed to take advantage of recent materials advances in this area.

Atma-sphere et al, There is one type of pivoted tonearm that exhibits the property of a low vertical inertial mass with a high horizontal inertial mass, a la most SL tonearms. That is the Dynavector DV series. Rather than try to translate what Dynavector says about this feature of their tonearm, I am quoting here the DV505 owners manual:
www.dynavector.com/etechnical/505manual.html
The verbiage hints at why a high horizontal mass has some advantages as regards low frequency resonance control. As I think I mentioned once before, there are also a few vintage conventional pivoted arms that have obvious added mass on their lateral aspects, added usually at the pivot, e.g., the SAEC, to name only one brand. My point is that there are possibly some theoretical advantages to having a low vertical and high horizontal inertial mass, combined in one tonearm. Ralph, I would be interested to know what you think about this.