Discuss The Viv Lab Rigid Arm

@lewm

Its a bit hard without drawing a diagram -

If you draw a line from the spindle to the edge of the record.( call it line A )

Then choose a null point on that line

Now draw a line ( call it line B ) at 90 degrees to line A intersecting the null to the armboard or mounting point - so you now have a T.

Normally I assume you would position the arm mounting along that 90 degree line such that the stylus swings an arc where it touches the null, but both sides of the null are underhung.

What I am suggesting is now move the mount forward so that when the stylus is forward of the null point.

Now when the stylus swings through the arc it should intersect line A twice.

So now the arm starts off underhung, then crosses line A and goes to overhung, then crosses line A again and goes to underhung.

In this set up the maximum tracking error is reduced, but you would still have the advantage of no skating forces due to offset.

Alternative Explanation 2

Alternately if you take your existing Rigid Float move the arm across the record.

The stylus draws an arc.

Draw a line through the spindle that crosses that arc at one point.

Now with the stylus positioned at that point, move the arm mount forward along a line 90 degrees to that point..

Instead of 100% underhung either side of the null you will now have both under and overhung. You should if I have my head right have reduced the maximum tracking error - potentially you could halve it - by having a mix of underhand overhung instead of 100% underhung.

Hopefully you can follow this.

By the way here’s another example of a 0 SideForce arm. Fidelix have been around forever.

https://exclusive-audio.jp/en/products/0-sideforce

 

 

 

 

With respect to the pivot and spindle, you can’t have both underhang and overhang at the same time.
I’m actually in Tokyo and contemplating the purchase of a Viv just to spite my dear friends Raul and Mijostyn. Their rigidity should not astonish me by now, but it does. In 1940 a couple of mainly German mathematicians published their solutions solely aimed at minimizing TAE at all costs and without any way of knowing what the negative consequences might be, insofar as all styli were literally “needles”, all recordings were mono, and the era of the Victrola for most listeners was still very much alive. For those gentlemen the achievement was solving a problem in geometry using math. Yet one version or another of their solutions was religiously adopted by companies that made tonearms from the end of WW2 to the present. I use the word “religiously “ on purpose. Is stylus overhang and headshell offset the audio equivalent of the 10 Commandments? I think that dogma is just as subject to question as is the idea of the underhung tonearm with zero headshell offset. What’s also puzzling is that no reviewer has a handle on the way in which the two approaches differ in their consequences. I too wish the Viv were more conventional in ways other than its geometry, and that’s the only reason I haven’t bought one, so far.

Great post!

Dover, a light bulb went on in my head. I think I now understand what you mean, but it still seems to be the equivalent of shortening the distance from stylus to spindle, which only moves the single null point closer to the spindle. Still underhung. 

@lewm 

Yes underhung with respect to the spindle, but when I say under and over hung with respect to a line at tangent to the null point

Have a look at the diagram here  ( figure 2 ) -

https://theaudiobeatnik.com/review-viv-lab-rigid-float-ha-tonearm-part-1/

With the arm in the middle position on the diagram, the stylus is at a null.

Now if you move the arm mount forward so the stylus is now forward of that null point, you can reduce the tracking error at the inside and outside of the record, increase the tracking error through the middle, but overall reduce the absolute maximum tracking error.