Arm geometry and null points

Thanks guys, that's what I thought.
The reason I had to ask Doug, is that I have just bought from Yip the Mint Tractor made for the Graham Phantom II standard arm which is, as you have said, the best template on the market IMHO.

For my other arms, the Copperhead and the DaVinci 12" Ref, I have the WallyTractor and the Feickert respectively.

I wanted to use the Mint Null Points inscribed lines to align the styli in my other arms after I had set up the correct Spindle to Pivot distances and Overhang adjustments using the other templates and I asked Yip if the null points were in the same positions and he did not know!!??...a bit worrying?

Regards
Henry

Henry,

Still not sure why you had to ask moi in particular, but thanks for clarifying.

Yes, you can use the Mint's null grids after setting S2P and overhang by other means. As Mark noted and you obviously understand, the Mint's arc won't be useful for any other arms, but the null grids will. Neither the null points nor the intercept angle of the grid (cantilever) at those points ever varies.

I wanted to use the Mint Null Points inscribed lines to align the styli in my other arms after I had set up the correct Spindle to Pivot distances and Overhang adjustments using the other templates and I asked Yip if the null points were in the same positions and he did not know!!??...a bit worrying?

Is it possible that he said that simply because he didn't know which geometry these other tools uses? Löfgren A and B for example have null points in different places.

Halcro, I share the same opinion as Jfd01. Probably Yip simply doesn't know what alignment was used for the design of each of your tonearms.

A 9 inch arm and 12 inch that are both designed for Lofgren A alignment will have the same null radii.

OTOH, a 9 inch arm designed for Lofgren A alignment will have different null radii from another 9 inch arm that is designed for Lofgren B or Stevenson alignment.

Practically speaking, the null radii have nothing to do with the arm length. The null radii have everything to do with what alignment was used during the design of the tonearm, and that is determined by the priorities (or whims) of the tonearm designer (to keep things simple, I'm leaving tonearm installation errors out of the discussion).

hth, jonathan carr

Hi Jonathan and Doug,

I made it clear to Yip that all arms were set using Baerwald geometry.

I think maybe he wasn't keen on me NOT buying 2 other Mint Tractors for the other arms?

Regards
Henry