Hi Lewn,
"What do you think?"
I prefer to refrain from criticizing particular design decisions of other tonearm designers or manufacturers, but I will try to comment( which will, inevitably, contain judgement, I know...).
In tangential tracking airbearing arms the disparity between eff. mass lateral vs. vertical is unavoidable, but could be reduced (Rockport, Versa Dynamics...). In order to achive that, the neccesary reduction in eff. length will cause warp wow and pronounced changes in VTA when switching from 120 to 200gr. pressings(to a lesser degree VTF too). Keep the arm longer and you'll have to add a provision for damping: eddy current brake(Dennison, Eminent) or add an anti-resonator(Eminent), all solving one problem for the introduction of one or several others.
If the arm cartridge resonance frequency is "split", a key argument by Dynavector, you will now have to avoid exitation of either(more difficult to achieve than you'd think), therefore Dynavector arms feature a massive eddy current brake. The "split plane " design is by no means an invention of Dynavector. Some famous arms(i.e. Gray 106, Shure M16 Dynetic...) preceeded them by decades. Those were used on non-suspended decks(broadcast console-mounted), so the risk of lateral exitation was reduced mainly to what record eccentricity could trigger. And they did it mainly to allow for the use of cartridges that "tracked lighter".
Bearing design for such an arm offers options not available to those sticking to "conventional" arrangements(like gimballed arms), so there are potential and in some cases realized advantages.
Once you use an arm with a high eff. lateral mass on a suspended deck or, to be found often, on top of a tall rack with tons of gear that is supposed to be rigid(hahaha....think Eiffel Tower with King Kong on the Observation platform swinging happily, huiii!), you'll invite all sorts of problems that may not manifest themselves directly, but through effects such as transformer saturation, increased power requirement or intermodulation distorsion.
Besides that, the shift of mass will shift the center of gravity of the deck, forcing it out of a level position. Not exactly desirable for zero friction arms...
An Oracle Delphi with ET2 tonearm was a rather popular combination at some time. While it could yield impressive sonic results, I never understood why it was promoted to that degree other than for marketing purposes.
The Dynavector's excellent bass rendition predominatly stems from the (eddy current)damping in the lateral plane. It's mass distribution is another reason.
Bass below 100Hz is cut in mono, purely lateral...
Best,
Frank
