Morch DP-8 arm on a Helix Two turntable

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.

Because this thread was brought to the fore, I see now that in March, 2021, Mijostyn likened the Dynavector tonearms to a Transcriptors Vestigial tonearm. Heaven forebid!  I have to guess that Mijo never used a Dynavector.  Very different. I am not insulted; just wanted to set the record straight. (I once also did own a Vestigial, mounted on a Transcriptors Reference TT.)

Thanks, D. I have a DV501 (given to me by a dear departed friend) and two DV505s. Only one DV, one of the DV505s, is in constant use on my much tweaked Lenco.  I prefer it to the 501 because of easier VTA adjustment, although I do know that many favor the 501 over the 505 for pure SQ. (On that table, I  change cartridges a lot, and I hate the "grub screw" method of securing VTA vis the 501.)  My question, for anyone, is that since the argument for high effective mass in the horizontal plane makes so much sense (to me), I have to wonder what is the counter-argument in favor of equalizing or nearly equalizing effective mass in the horizontal and the vertical.  Fremer seems  to favor that approach but I have never seen a convincing argument for it.  I have an FR64S on my Victor TT101, but all my other tonearms are of the conventional type; no special effort is made to increase horizontal mass over vertical mass.

Dover, Those side weights are a feature I mentioned once before in reference to tonearms that have a high effective mass in the horizontal plane.  As I am sure you know, that is the raison d'etre for the side weights, in the case of the DP8.  The idea being you want a high effective mass in the horizontal plane so that when the LP calls for reproducing a low frequency signal, the tail will not wag the dog, so to speak; the cartridge will be held stationary with respect to lateral movement while the stylus is then able to trace the wide horizontal swings required for low bass response. I'm sure you know this; I am repeating it for the benefit of some others who have criticized linear trackers along with all other tonearms with high effective mass in the horizontal plane, a la Mike Fremer, who rarely misses an opportunity to bring up the subject.  The Dynavector, which I own too, is another example of a tonearm that introduces damping to hold the cartridge steady in the horizontal.  I feel that the DV does a good job with bass response, but I have never heard a Morch.  What would be the opposite argument?  Fremer never makes the argument very well except to assert that "you want" horizontal and vertical effective mass to be about the same.

Thanks for the clarification, Dover.

Mijostyn, I appreciate forthright comments, but if they represent opinions presented as fact, then I take umbrage unless there are also supportive data provided. In the case of the Murch DP8, what I see is a tonearm that does in fact conform to most modern conceptions of what makes a good tonearm, except of course for the central fact that it is a Uni pivot which some people like and some people don’t like. On the other hand, I take Dover’s opinion very seriously, because he tells that he has used the DP8 in his system and he compared it to other tonearms, one of which we can call a modified unipivot (Kuzma 4-point). As for me, I am a little suspicious of tonearms that started life as unipivot designs and later incorporated  very significant crutches that no longer placed them in the Uni pivot category, like the Kuzma, the VPI, and the third brand that escapes memory at the moment. But you won’t find me expressing an opinion of them, because I have never heard them, and because each has its own set of devoted followers, some of whom I respect a great deal.

But to your point, I think it is fair for you to say you don’t like Uni pivots and then give a list of reasons why you don’t like them in theory, while also admitting you never heard the Murch DP8. 

Mijo, Admittedly, I have never owned a Morch tonearm, but they, particularly the model 8, are very highly regarded among those who do use them.  I don't know how you can dismiss it out of hand in this case, unless you have heard one.  I know you categorically dislike all unipivots, that is your bias in this case.  Can you point to even a negative review on the internet to justify your advice to the OP?  The Morch 8 is the one I would choose over all the other Morch tonearms, were I in the market.