Pivot to Spindle distance

As long as pivot-to-spindle distance is close enough, you can still get overhang right due to the slotted head shell mounting available on most arm/head shell combinations.

Mark, just went to your system page, good looking system by the way but I have a question for you. In the description of your table you make reference to the 10 inch arm doesn't sound much different from the 9 inch arm it replaced, my question is, did you use the same mounting/arm board and set up jig that you used for the 9 inch arm? This might be the reason for the 5 mm difference in your ps2 measurement. Enjoy the music

Overhang is one thing, ARC is another.

Any longer arm, any longer spindle to pivot distance will have a ’flatter/less curved’ arc, that keeps the stylus in the groove ’straighter,’ i.e. less deviation from the 2 null points of any pivoted arm.

Each arm has specified null points, based on their arms ARC. There are 3 major variations of null points, so even if you follow the recommended null points, from a ’too close’ pivot point, you are probably within the range of one of them.

There are charts about arm length/deviation/distortion values, the differences are very slight, that’s why I went for my 12.5" arm, if long, I thought lets get the ’least’ deviation! I didn’t plan on hearing any difference, perhaps a mighty minimal (miniscule) amount of groove wear, I was doing a new TT, just wanted to do it.

Overhang is the final geometry of that arc.

Critical? It’s the same as having a slightly shorter arm IF you can achieve the proper overhang, i.e. short cartridge body, long mounting slots on arm or headshell ... that let’s you ’get’ the stylus presumably ’back’ enough.
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Images of Null Points

https://www.google.com/search?rlz=1C1SQJL_enUS881US881&sxsrf=ALeKk00QjTO47rthOxtCNM83jWfclhgTYQ:...

3 null point recommended methods

http://www.dvautier.com/nullpoint/null.htm
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Sounds great! If still curious, see if you perceive any difference regarding the outer edge, middle, inner tracks, that is the essential difference for the 3 null point systems
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They make these alignment discs for specific arms, but any one of them has enough lines that you can find the distance for your Tonearm.

https://www.wish.com/product/5cd656f57be1080861950976?hide_login_modal=true&from_ad=goog_shoppin...

The other side, smooth, is good for initial anti-skate setting, then you need to confirm/refine by listening. Something with a solid center, and 'equal' l/r elements, including live audience noise (confirm it's a wide audience and performers are center on the stage.

I use side 2, tracks 2 & 3 for anti-skate refinement, 3 world class guitarists play together

https://en.wikipedia.org/wiki/Friday_Night_in_San_Francisco

I just looked again and see your distance is ’over’. The concepts are the same, in your case, a longer cartridge body, longer slots in the tonearm or headshell let you get the stylus overhang correct. Now you have achieved an ARC of a 5mm longer arm.

However, a 5mm longer arm ’might’ have a different recommended overhang than what is specified for your arm’s length/exact pivot location.

Again, sounds great!