How much difference if the tonearm is mounted 5mm

Dear Dang,
In some responses, it seems the responder is confusing pivot to stylus tip distance with spindle to pivot distance.  If the spec for your tonearm is 212mm, spindle to pivot (P2S or PTS), then it is folly to tolerate a 5mm error in that parameter, as CLeeds and maybe some others already said.  If you are using a Dr. Feickert protractor, and if you observed a big problem when you set P2S to 212mm, then in some way you may be using the protractor incorrectly.  I use one, and one of its best features is the capacity to set up P2S before alignment of the cartridge body, because the arm that extends from spindle to pivot point, on the Feickert, is calibrated in mm.  Once one has done that, then aligning the cartridge is the veritable piece of cake.  I'm not sure what your problem is, from this distance.  Perhaps you are mislocating the pivot point on your tonearm.  If the manufacturer specifies a 212mm P2S distance, then the headshell should not be 4mm out of whack.  Only other possibility I can think of is if the tonearm is set up for Stevenson alignment, not the standard for the Feickert.

First of all, Hola', Raul!
Second, Dang, are you saying that after setting P2S at 207mm (which is quite short for even a 9-inch tonearm), your cartridge could be perfectly aligned with each of the two grids on the Feickert protractor, including the front to back alignment of the cartridge body? Your tonearm is totally unfamiliar to me; is it "vintage" or a brand new product?  If vintage, the tonearm may have been designed for Stevenson alignment, especially if it was made in Japan.  The Feickert is designed for accurate alignment to the Baerwald standard, which is very different from Stevenson.  (Which by the way also means that you should not use the Feickert if you want to try Stevenson alignment.)  I cannot recall whether the Stevenson is "shorter" in pivot to stylus tip distance than Baerwald or Lofgren, or whether it's the other way around, but possibly this is why your alignment appears to work, but you would have had to twist the cartridge body with respect to the headshell to make it work, i.e., to achieve the proper offset angle so the cartridge body aligns with the grids on the Feickert.  Is that the case?  If so, maybe another mystery is solved.

Third, DSGriffith, I don't really follow your argument, but I have to agree with Raul, who after all is agreeing with me.  On the other hand, I take your point that aftermarket headshells or swapping OEM headshells between two different tonearms may complicate the alignment problem. For a given geometry (Baerwald, Lofgren, or Stevenson) with a given tonearm, theory predicts there one and only one "most" accurate alignment (defined as that which gives minimal tracking angle error on average across the surface of an LP).  (I'm aware that Baerwald is identical to one of the two Lofgren methods, A or B.  Can't remember which.)  I am not one who believes you need to be within a micron of "accurate", but 5mm seems a huge error.  There are cases about which I have read where persons in the field have come to disagree with the manufacturer of this or that tonearm on what is really the best P2S distance, etc, for a given tonearm.  This is true for the FR64; FR says 230mm, gurus say 231.5mm.

ds, Have you really observed such errors?  I am putting myself in your shoes.  In my thought experiment, I have a new tonearm, and the manual says to mount it so as to achieve a pivot to spindle distance of 215mm (for example).  What measurement would I make of my sample of said tonearm in order to know that following this instruction would be a mistake?  I guess that could be distance from pivot to center of headshell slots, for one example.  But manufacturers don't often even supply that spec.  So how did you know that you had a "bad" sample of any particular tonearm?  I respect that your training and life experience may have equipped you to detect and solve such problems better than I.  In my imagination, badly made samples would be more likely to have out of spec bearing friction, much more likely than to be significantly (could define as +/-0.5mm???) longer or shorter than specification.  As I noted above, there is also the case where thorough analysis of the geometry might lead one to prefer a different P2S for a given tonearm from that which is recommended, but that still assumes all of the samples of that tonearm are alike.

Dear Dang, I have not mounted a cartridge in several months, but it seems to me that my Feickert protractor, which is one of the older versions (assuming there are newer versions, which does appear to be the case), is designed for only one geometry, which I think is Baerwald.  Perhaps yours is different.  If yours has a Stevenson option, you might try it if only to verify that your tonearm was designed with Stevenson in mind. In which case, the headshell and the cartridge body will align with each other only for the Stevenson option.  This does not mean that you must use Stevenson.  It only means that you will be twisting the cartridge body with respect to the long axis of the headshell in order to attain any other geometry, and probably also needing to move the cartridge screws to the ends of the slots in the headshell to get Lofgren or Baerwald.  If you care to do it, you could try the recommended 212mm with Stevenson parameters.  If that gives you an alignment where the cartridge lines up with the headshell and the screws mount comfortably, I think we've explained your findings.  If you set up a "Stevenson" tonearm according to Lofgren or Baerwald, the recommended P2S is going to seem too long and the screws will be out at the end of their allotted travel, or beyond, and the cartridge will be "twisted".

ds, I haven't the time right now to digest all of what you wrote, but it seems in the first instance that you are talking about not trusting the template supplied with and for the tonearm.  I fully agree that this can be problematic.  I've had bad experiences in that regard myself.