Raul, You wrote, "VIV comes with no off-set angle and with a TAE of around 10° and due that only exist one null point the TAE 90% of the time is truly nearr to those 10°..." That’s just not true at all. Only at the extremes of the arc the tonearm makes across the surface of the LP would the TAE reach its max error of 10 degrees. And please may I remind you for the second time that the "10 degrees" data point comes from the Yamaha engineer in reference to the Yamaha underhung tonearm mounted on their GT5000. For the Viv or any other underhung tonearm, the TAE would be zero at the single null point, which you can choose to place anywhere on the playing surface when you choose where to mount the tonearm. As the arm moves toward its single null point, TAE is gradually and pretty near linearly decreasing from its max at the outermost grooves to zero. Once the stylus moves past the null point, then TAE gradually increases to whatever its max value (now in negative degrees, because the angle is opposite in direction) at the run-out groove. I don’t recommend it, but I think the Viv comes in assorted lengths out to at least 11 inches and maybe to 14 inches, where the max TAE values would be way lower than 10 degrees. So if TAE is such a problem, one might consider the longer versions.
Earlier, I asked you to cite the reference you quoted in your post describing the logic of conventional tonearm geometry. Can you do that, please? If so, thanks a lot for your effort in doing that research.
Dogberry, TAE is not per se a "distortion". It’s a geometrical error; we know that distortion arises therefrom, but how much and of what quality and what consequence to our SQ, that is up for debate. For example, if we perseverate over TAE, then what can we also do about errors in zenith. A stylus that is not exactly symmetrically mounted on the cantilever can add up to +/-5% to TAE and can also eliminate null points, unless one accounts for it.