Help me understand cartridge alignment

I think the arm must be off somehow. I've explored every option. Tomorrow I'm going to adjust the PTS by 2.5mm (I measure today) so an SPU will hit Baerwald exactly.

Raul, I just saw your post. What is "tracking distortion"? Are you talking about harmonic distortion, IM distortion, or what? Can you refer me to the source of your data, or have you yourself made these measurements? I am certainly willing to believe there is a relationship between tracking angle error and distortion of some kind, but I have not seen the data, until now possibly. My private hypothesis is that stylus overhang and headshell offset angle taken together are examples of the cure (for TAE) being worse than the disease. Invented 80 years ago by a few guys, who were more mathematicians than audio engineers, to drive us crazy. I realize that my view is not the norm, so I am not anxious to argue about it. But tell me how "tracking distortion" was measured, please. And thanks.

Dear @lewm  : Were measured through the Löfgren A-B equations in reference to cartridge/tonearm alignment and under IEC, DIN or JIS standards.

This is not new and this is not the first time I posted.

" is that stylus overhang and headshell offset angle taken together are examples of the cure (for TAE) being worse than the disease. "  , probably you are rigth but where are those alignment equations that proved it, at least Löfgren did it.

I think in the last 15 years you are sticked to your opinion and nothing wrong with that but I wonder why after 15 years you just has a " wondering " instead to have the maths that proved.

R.

You are wrong about my "opinion". For most of my audiophile life, I went along with the idea that very precise alignment is important. Only in the last few years have I begun to seriously question that proposition. And the key word is "question". I am not about to say that alignment is NOT important. And I do align my cartridges carefully. But I don’t fret over a mm or 2, just because of my own experience with underhung tonearms and the fact that once or twice I have discovered that my alignment of overhung tonearms was way off (only because I periodically check with a protractor) without any audible associated deficit in SQ. This may be because, even based on your own data above, the associated distortion (which I still do not understand the nature of) is low compared to the sum total of all the other distortions associated with vinyl.

The reason I am still in the dark as to the nature of the distortion associated with minor misalignment of an overhung cartridge is that your response, "Were measured through the Löfgren A-B equations in reference to cartridge/tonearm alignment and under IEC, DIN or JIS standards." suggests to me that you misunderstood my question or I misunderstand your response. Do you mean to say that (someone) measured actual distortion of the audio signal in relation to IEC, DIN, or JIS standards?  If that is what you mean to say, what sort of distortion was being measured?  To say the standards used is not to describe the nature of the distortion.  What I am asking cannot be answered by any equation, because an equation will give you a theoretical answer only, and my real question is whether reality conforms to theory.  Lofgren, Baerwald, and maybe even Stevenson all did their work around 1940, so far as I can find out.  Way before stereo or any high fidelity home audio.

A 2.2mm shift in the mounting hole dropped the SPU I have right into place for Baerwald geometry. While I thought the sound was great with it off by the 2.2MM (I know I said 5 but I was wrong in the end) it turns out that it's better properly aligned.

I didn't really notice because even improperly aligned, the new 401 w/SPU is so much better than my old setup!