Spindle-To-Pivot Distance

Dear Raul, I don't understand what you want me to say.  I can only say (again) that my experience with underhung tonearms using zero headshell offset angle suggests that precise adherence to any algorithm that posits minimizing tracking angle error as its primary goal (I guess this would include Baerwald, Lofgren, Stevenson, and any other similar solution) is over-rated as it applies to maximizing SQ from vinyl.  I nevertheless do adhere to such geometries when I set up my conventional pivoted overhung tonearms that have a headshell offset angle.  I have two "reasons" for thinking the practice may be over-rated: (1) Like I said above, the underhung tonearms with zero offset generate very large tracking angle errors other than at the single null point one can attain with such tonearms.  So if there is zero tracking angle error (TAE) at the null point at the center of the playing surface, there will be several degrees of error (on the order of +/-10 degrees for a 9-inch underhang tonearm, as I recall) both at the inner grooves and at the outer grooves.  You can do much better than that with Baerwald, Lofgren, Stevenson, etc. Yet, I don't hear the problem.  You can argue that I am deaf or that my system is not good enough to allow me to hear the problem, if you want, and (2) I have once or twice inadvertently set up conventional pivoted tonearms incorrectly, only to discover my error weeks or months later.  I then "fix" the error, but I don't hear a big upgrade as a result of doing so.
I realize that I am in violation of a vinylista mantra, but that is my opinion.  No big deal in the course of every day life.  I still play by the rules.  I have to wonder what Baerwald and Lofgren heard with what must have been 12 or 16 inch shellac 78 rpm mono recordings played with spherical styli.

Rauliruegas if you read through the posts carefully  you will see  both lewm  and myself  are questioning  the null point concept.   I  am not sure about  about  how important  the whole thing is.  You might want to listen to a RS tonearm and  see it breaks all of the status quo rules yet still sounds spectacular.  

Maybe  have a person  get a album you are not  familiar  with then have him play it  choosing different  spots , with you not looking.  Then  tell him where the  null points are on it .  Then you will know first hand  if you can  or if it matters.  Another  test would be have your friend  change the offset on the cart then play album.  Have them change the offset around  including the right spots.  Write down you hearing findings then compare  notes with  his placements. 

When I did  the test the two arms where attached  to the same table and if you noticed  I  said I really did not do enough testing to give you a  any  real findings.  But I can say I  have not  heard any wild distortion  issues  with underhang and 1 null point.  

I realize  humanity  wants absolute  answers to all their questions  but music reproduction  has far to many variables  to  be able to do the the  math run the test equipment  and have great sounding gear.

So back to the OP  all the stuff was brought  up  give him some ideas different  than the status quo.  Weather they are better or worst  is up in the air.  You already know they move the null points around  so where are the perfect spots.  

Enjoy the ride
Tom

It's possible to use the arm with a slightly shorter spindle-to-pivot distance, but the standard geometry for the arm will not work.  A new geometry and alignment system has to be generated.  There is a geometry generator on vinylengine.com .  

Will that setup work as good as the one designed for the arm?  Maybe.  Will it be as easy to set up as the stock alignment?  Probably not (IMO, 95%+ probability of being more difficult).

@Lewm.  If you think it sounds OK with 10mm too much overhang that's fine with me.  Just don't bother us.

Guys, forget the null point issue. It is not the problem. Overhang is the problem. Getting the right overhang would require sliding the cartridge back in the head shell towards the bearing. There is no arm I know of that is that adjustable given the limits set by the turntable. Running a tonearm with an overhang 0.5 cm over spec increases the skating force. The force vector will shift clockwise as the tonearm travels towards the spindle and eventually the stylus will pop right out of the groove and arm will zing right across the record with obvious results. 

You will either have to manufacture a special tonearm board as jasonbourne52 recommends or get a 9 inch arm that will fit. Long arms are not a panacea. They do lower tracking error but at  significant expense. Many of us, myself included think it is a raw deal.