What defines a good tonearm

I can only assume that you attended a school where the works of Aristotle still held pride of place.For most argument by definition is no longer valid.

I'm with Stan.

Having done this for 50+ years, I'm convinced there is no "best" tonearm. To think otherwise is quite short-sighted IMO.

I do, however, believe that some tonearms perform best with certain cartridges. One example is the Graham Phantom/Lyra Titan i combo. Absolutely killer. OTOH, in some tonearms the Titan i performs less than optimally due to the incredible energy it generates.

YMMV

Dealer disclaimer

I am not asking for what is the "best" tonearm, as that is a much too subjective question, as the responses in any thread you look at on this forum would reveal. I simply believe that there are certain goals that all tonearm designers are trying to achieve, and since they are using different means to achieve those goals, they are likely to have different degrees of success. And certain of those common goals might be more difficult to achieve with certain design choices than others.
Any designer knows that when they chose a certain design theory, they are accepting that they have to deal with the inherent weaknesses in that theory and their ultimate success depends on how well they deal with those inherent weaknesses.

My original question was intended to be limited to pivoted arms, not parallel tracking arms as those design limitations are generally much different than pivoted designs, as Acoustat6 points out. I have an ET2 that I can use if I want to go that route.
Again, my original post was asking if there was some inherent benefit to a fixed pivot design that makes it worth the perceived extra effort required to design and construct them. It seems most of the more recent high end tonearms are unipivots or some variation thereof.

Audiofeil,
If the Titan generates a lot of energy, would it not be a good candidate for something like the Townshend Rock silicone trough headshell damping system? My use of that trough with other cartridges seems to result in a much cleaner, smoother sound than without.

If you have an ET 2 then you allready have the best tonearm. Any other questions, just ask.

Dear Manitunc, To respond to the closest thing to an answerable question that you have posed, with a unipivot there are issues related to not only adjusting azimuth but also maintaining a constant azimuth across the surface of an LP. The Graham and Talea unipivots have addressed this issue, but it is an issue nevertheless. With a unipivot one also has the question of the stability of the bearing. Excess vibrations disseminated from the cartridge could cause the arm wand to rattle, causing bearing "chatter". Many unipivots use some form of damping to eliminate or ameliorate this phenomenon. On the other hand, with a fixed bearing tonearm, there are issues related to bearing friction, maintaining constant friction over time, etc. Like someone else said, I have become convinced that execution of the design, not the nature of the design, is the major determinant of the performance of the tonearm. But this is pretty obvious, so I am not sure what you want to talk about in this thread.