Fidelity Research FR64s Headshell dilemma

This is so strange, do you really think that Ikeda, who designed all FR tonearms, and later went on his own with Ikeda tonearms, have no idea about "error" in PS distance ? IKEDA are modern tonearms, designed not in the 70’s like thos old FR. The PS distance is absolutely the same 230mm. In your opinion IKEDA did not realize an "error" in 20 years ?!

I have FR 64s, FR 64fx, Ikeda IT-345
For all of them PS is 230mm, but one designed in the 70s, another in the 80’s or 90’s

Not sure if this is directed at me @chakster but I am trying to figure this out too.  Why is the 231.5 recommended by some when the manufacturer recommends 230?

Not sure if this is directed at me @chakster but I am trying to figure this out too.  Why is the 231.5 recommended by some when the manufacturer recommends 230?

Question for everyone.

It's a conspiracy theory ? 

I just use what Ikeda suggested us to use, i don't care about some gurus. In a conventional headshell cartridge still can be adjusted for any alignment methods without changing PS distance at all. Some headshell have this type of overhand and slots to twist a cartridge body left of right. 

@rauliruegas 
I do understand what you and others have written. My simple question related to the fact that on my alignment guage and as it transpires others that have Lofgren and Bearwald alignments cannot get their cartridge out far enough in the headshell when one mounts the arm at 231.5mm PS distance, whereas at 230mm I can get it aligned. 
The vinyl engine calculator has nothing in it about how far in the headshell you mount the cartridge, nor about how it is twisted in the headhell. That said it was good to learn about the other things that have been written on this thread - which i will no doubt digest and re-read several times

Dear @karl_desch : " is that the P2S mounting distance is specific to the tonearm regardless of alignment choice. "

Not really/exactly that.

The P2S distance is specific to two characteristics: first the alignment choosed and second the tonearm EL.
Why is that? because each kind/type of alignment calculates its own and specific overhang for that EL and P2S distance is the difference between the tonearm EL and overhang. As overhang always change with the alignment choosed then the P2S always change with different overhang: easy. In the same way each aliognment type has different null points that are specific and never change for that alignment type.

When for whatever reason and at random we change the overhang what we are doing is changing the tonearm EL and this means that we need to change the P2S too to permit that those tracking error and tracking distortions stay at minimum in the alignment choosed.


""" with the FR-64s suggests 231.5 is correct and not 230.0 for P2S, what is this possibly based on? """

It’s not that 230mm is not correct because is near to be correct ( 230.09 is the correct value. ) for what the designer choosed as tonearm EL. The designer not choosed that 230mm, his choice to make the tonearm design was 245mm in EL and because he recomended to use Stevenson alignment the P2S distance comes as 230.09mm. Repeat 230mm is not the designer spec it’s only a consequence of the calculation of Stevenson alignment for a 245mm EL tonearm.

What happens when instead of 230mm. you have 231.5mm? , well you are changing the tonearm EL along the overhang and offset angle.
With 231.5mm the EL change from 245mm to 246.32mm.

Now, that EL change has an impact in the quaklity level we listen through?. Well if we want to " hear " a better performance then we will listen it even that in reality we can’t detect atrue improvement.

Why say I that? because please tell me whom of us can detect the difference in quality between a tracking distortion of 0.73% against 0.72%, this is 0.01%: it’s just imposible to detect for any human been especially that that 0.01% diference is changing in extremely tiny values at each tracking groove ! ! !

All of us know that as the tonearm EL goes higher the tracking error and tracking distortions goes lower if and only if the set up is absolutely accurated and I mean not only the tonearm cartridge set up but the VTA/SRA/AZ/VTF for we can have the posibility to listen " something " as a differences in quality levels.
So when the difference in EL ( FR/Ikeda. ) is of only 1.3mm and the resulted overhang only 0.09mm is really almost imposible to detect it. With larger EL differences we can do it.

R.