Morch DP-8 arm on a Helix Two turntable

@lewm ​​@cleeds I owned a Vestigial arm on an LP 12 and have experience with the Dynavector.

They are alike in that their horizonal effective mass is much higher than their vertical effective mass. Both had/have their vertical bearings out at the end of the arm. They just counterbalanced them differently. The major difference is that overall the Dynavector is heavier and is infinitely more useful with modern cartridges. The Vestigial arm only worked with the most compliant cartridges. The problem with both arms is that the vertical and horizontal compliance of most cartridges is very similar. Another issue with the Dynavector is that in the horizontal plane it has a lot of inertia. It deals with this by using magnetic damping. In the vertical plane it is going to be too light for the less compliant cartridges. It's arm lift is a rather flimsy mechanism under the arm that could be a real resonance problem. 

I made the mistake of buying a Vestigial arm and will try not to repeat such a mistake. Making a device more complicated than it has to be is more than likely problematic. Now I would never consider an arm like the Dynavector as there are so many great arms that avoid unnecessary complexity and tic all the right boxes. 

You mean the Schroeder and the Kuzma, don’t you? I actually don’t disagree with the premise there is a loose connection between the Vestigial and the Dynavector. They are both pivoted tonearms, and they both dissociate vertical from horizontal motion. It’s been so long since I owned that Vestigial that I cannot recall whether the rear pivot was limited to horizontal motion or not, but I guess it must have been. But the Dynavectors I have actually used a great deal with several different cartridges do have high horizontal effective mass and moreover use a pair of magnets to retard resonant behavior at the rear, and they make excellent bass compared to running the same cartridges in other tonearms I also own. Are the Dynavectors the best ever, in my opinion? No, I don’t think so, but very high quality and very good sounding with a wide variety of cartridges.

You wrote, "Another issue with the Dynavector is that in the horizontal plane it has a lot of inertia. It deals with this by using magnetic damping." How does the magnetic damping ameliorate the high inertia? I always thought the magnets dampen any resonance that does occur, mass (and compliance of the cartridge) notwithstanding. As to it being too light in vertical effective mass, high mass headshells or adding mass to any headshell works to make the tonearm compatible with heavy or low compliance cartridges, which usually are one and the same anyway. My criticism would be that the vertical component of the tonearm is so short that the effect of warps to alter VTF and etc is magnified, compared to a conventional tonearm. You have often mentioned that it is no trick to increase the mass of a light tonearm; I agree. The DV505, with which I am most familiar, has no arm lift, aka cueing device. You lift the headshell using its tab. The DV501 has a cueing device, looks just as solidly built to me as any other. DV507 also. But I am not about to claim Dynavector uber alles.

Your post raises an interesting question. Since bass frequencies are predominantly encoded as lateral movements of the stylus (or so I have read), is it not the case that lateral effective mass and horizontal compliance of the cartridge ought to be considered in matching tonearms to cartridges by resonant frequency? But typically we use the vertical compliance and vertical effective mass in that equation for resonant frequency. We audiophiles have made a complex situation too simple by relying upon that one equation.