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. 

Hi Vassilis_t

The Morch is a mass loaded unipivot arm with a spindly arm tube. It is unstable and nowhere near stiff enough.
The Helix two is an incredible turntable. Wait until the vacuum platter is ready. If you talk to Mark Dohmann he will tell you not to get that arm. You can email him directly.  The ultimate arm for that table is a Schroder LT. They sell the Schroder CB but the LT is the one for that table. Great
table!

Other posters which I assume means me do not have to listen to every single tonearm out there to know what makes a good arm and what makes a lousy one. The Morch violates several key parameters. Having set up and listened to many arms experience is the best teacher. People buy the Morch because they think it looks cool. What they think it sounds like means nothing. People think all kinds of inferior equipment sounds great especially when they just spent a lot of money on it. Dover's experience is rather typical.
@lewm, it is not just my bias. It is the bias of many people including the designers of unipivot arms! Both Graham and Basis have gone out of their way to correct specific unipivot deficiencies. Cartridge manufacturers recommend against them. 

I get a lot of animosity because I do not pull punches. Political correctness only perpetuates problems and inferiority. An opinion stated is one that can be argued, verified or debunked.  

@lewm , what is the argument for a high horizontal effective mass?
Cartridge manufacturers do not specify a vertical and lateral compliance for cartridges. Are they the same? From my experience they are very close. The arm I have been using for years has a slightly higher horizontal effective mass than vertical. With a host of cartridges the lateral resonance frequency is always a little lower than the vertical resonance frequency. On top of this you have the moment of inertia which determines how much torque is required to move the tonearm in a given direction. This is generally higher for higher mass tonearms and again there are both horizontal and vertical moments of inertia. In any arm the lower the moment of inertia the easier it is for the cartridge following the groove to move the tonearm. Raising the horizontal effective mass is going to lower the horizontal resonance frequency and raise the moment of inertia. This can and does result in a low frequency horizontal wiggle that can be seen on an oscilloscope. I have seen it in air bearing tangential trackers. Because the DV501 and 505 are pivoted the horizontal effective mass would not be as high as an air bearing arm even though the DV's look massive. It would be interesting to check both vertical and horizontal resonance frequencies to see what you have. My instinct has always been to have the horizontal effective mass slightly higher than the vertical to spread out and lower the resonance peak but close enough to keep the resonance frequencies between 8 and 12 Hz preferably under 10 Hz. This has always worked well in my tables and ones that I have set up. I did own a Transcriptor's Vestigial arm once, sort of a light weight version of your DVs. It was an awful arm because it's vertical mass was just too light. It took me 6 months to realize there was no way I was going to get that arm to work well.