Ikeda IT-407 tonearm geometry


I’ve read all there is to read on this subject and never got satisfaction. It inspired me to ask this question earlier.
“Cartridge alignment with non slotted headshells”. 
The main reason I have a problem with these headshells is with my Ikeda it407 (chrome) tonearm, the cartridge must be twisted quite a bit in towards centre.  I have a vintage audio technica headshell with fixed holes and I don't even need a protractor to see that it won’t work. I don’t think stevenson alignment is this bad? I don't have a protractor with stevenson. My pivot to spindle distance is set perfect using my smartractor. I’m quite sure it is not possible to use an spu headshell in my Ikeda with the tonearm at the recommended distance without being seriously out of alignment. I’ve researched this online and I’ve spoken to Bill Demars at Beauty of Sound.  He said that the recommended pivot to spindle distance is probably wrong and some people position at a further distance. He agreed about spu in spu headshell in the ikeda arm not being ideal. I’ve never heard if anyone has asked Ikeda these questions about their arm. 


I do really like this arm, the way it sounds and the fact that is has a removable headshell, 
I’d just like to have better understanding of it? 



sdrsdrsdr
Dear @sdrsdrsdr  : I posted in that Analog Planet thread because not even M.Fremer understand it the whole subject at 100%. I explain my take on the alignment issue and there I explained how was manipulated the parameters for that comparison alignments subject in the thread.

R.
Before anyone will tell how Michael Fremer can hear distortion please read this post about his favorite tonearm called SAT. You will be surprised to read about SAT tonearm geometry, this is Michael's favorite. 
Dear @lewm : Your post has no sense for me and useless to this thread.

Btw, 1938 was the year E.Löfgren alignment studies and in 1941 Baerwald appeared with the same Löfgren A solution, nothing new with.

Who cares what was available back then. 
Certainly not me or Löfgren because it not matters to calculate tonearm today or back then overhang and offset angle ! ! !. The Löfgren solutions are valid then and for ever no matters what.

Your post ? ? ? ? 

R.
I was struggling to remember where I have saw the text which have changed my mind about alignment
It’s Stereophille
https://www.stereophile.com/reference/arc_angles_optimizing_tonearm_geometry/index.html
and if to "cut" the core is in the very end so will just copy it:

In all that has gone before, we have assumed that the Löfgren-Baerwald approach of minimizing the maximum LTE distortion across the modulated extent of the groove is indeed the optimal one. But there is good reason to suppose that it isn’t, because lateral-tracking-error distortion is only one form of distortion afflicting vinyl-disc replay. Another source of distortion is tracing error, caused by the replay stylus being unable to follow the same path through the groove as the cutting stylus. In large part this is a function of the shape of the replay stylus, and depends critically on groove curvature. Because of this, tracing distortion worsens toward the end of a record side, as the waveform cut into the disc bunches up.

Although tracking-error and tracing-error distortions are different, there is clearly a case for supposing that, as tracing error increases toward the end of the side, tracking error should decrease. In this case, the optimal arm/cartridge alignment might be one that results in a distortion-vs-groove-radius curve like that in fig.10. But as tracing error differs according to stylus type, this approach also suggests that arm/cartridge alignment should vary accordingly, with a bigger disparity from the conventional alignment for a conical stylus than a line-contact stylus. The concept of a single "right" alignment would then be redundant.


Dear @bukanona : That’s why Stevenson is no truwe alternative alignment and you can see it in the analog planet link that posted @sdrsdrsdr .
Yes, the tracking error is independent of what your link stated but has a relationship that we can't just forget. Btw, the article gentleman said that to align the cartridge body through protractors but in reality we all know that what be stay perfectly aligned with the protractor lines is the cartidge cantilever.
R.