Why use a super accurate cartridge protractor

I have a Graham Phantom arm, which comes with the cartridge set-up jig. While I don’t have the jig in front of me, IIRC, there are 2 markings (for 2 different alignment curves) roughly around 1mm apart, which is a big difference considering the precision level members are talking about here.

Now, as John Gordon and Dertonarm pointed out in another thread (if I understand correctly), which alignment curve to choose really depends on the inner and outer radii of the groove area, as well as the music piece and, of course, the users’ preference.

So, I really fail to see the need for an ultra precision alignment protractor, as the “best alignment” is probably different for different LPs and individual users. Taking the Phantom arm, I suppose even if I “misaligned” the cartridge and placed it somewhere in between the 2 markings, I would just get slightly different null points than the 2 standard alignment curves. This might, or might not, be a good thing depends on the LP played.

Am I missing anything?

To answer the original question: no reason at all. Unless you can't hear a thing but want to feel like a true purist audiophile.

Thekong, The distortions we are talking about are the
opposite of each other. We are of course interested in the least (aka 'minimal') distortion but what about the maximal 'kind'. The so called 'zero points' mean minimal distortion
at those 'points' on the record radius. But there must be
the corresponding max. distortion at some other 'points'.
Well it seems to me that we should worry about those also.
I have never seen any numerical values for those in this forum. It may be the case that while I feel 'proud' about my own selection of the zero points my records are in a
sade state because of my choice?

Regards,

Hi Nandric, I agree with you that we should also worry about the max. distortion, actually maybe more so than the min distortion, as it is already quite small.

Thanks to those who've replied so far, it's been interesting to hear the different approaches and perspectives. Like Stanwal,I think the difficulty of setting dead on correct pivot/spindle distance is something that could use more attention in devising set up tools. I still remain unpersuaded as to obtaining superior results with a Mint vs. less precise methods IF one still has to "make the final adjustments by ear." (Assuming one has properly set up spindle/pivot distance.) In the cartridge setup instructions with the Vacuum State Guru protractor, Allen Wright says that after checking many cartridge alignments with final adjustment tunings done by ear, there is a consistent trend of finding settings about 1.27mm behind traditional Cotter points on an alignment arc. After spending part of last Sunday setting up an Ortofon Kontrapunkt H with a super fineline stylus, I ended up very close to those points myself.