While doing some maintenance on my VPI TNT 6 table, I measured the pivot to spindle (PS) distance and it is 298mm. This is correct for the original JMW 12.7 tonearm and VTA assembly. A few years ago, I updated to a 12" Fatboy Unipivot and just realized today that the Fatboy's PS distance should be 300mm and not the 298 mm I have. FYI, the VTA assembly is mounted on a removable 4" wide tonearm board.
Questions:
Is there a way to compensate for this 2mm discrepancy? I'd really prefer not to make another arm board to get the proper 300mm PS distance.
Is there a way to align the stylus that will minimize any ill effects from this discrepancy?
Is the 2mm discrepancy negligible?
Thank you in advance for any advice you can offer.
JohnK,
Thanks for your comments. I am using the Dr. Feickert protractor and can get the two null points pretty much dead-on. I'm just off by 2mm on the fulcrum. I have an extra arm board and was planning to fashion another one with the correct PS distance 300mm but noticed there isn't much room to move the VTA platform. The right rear corner of the VTA is just 1mm away from the right rear tower, so nowhere to go. I will try to see if there's any wiggle room in the VTA base mount or maybe at the uni-pivot needle assembly. If all fails, I'm pretty satisfied as it sounds now.
To my mind a 2mm discrepancy is not critical, particularly if you are using the VPI gauge or something like the Feickert protractor. Both will compensate for the 2mm difference.
If you really want to hit 300 exactly, there may be enough play if you loosen the screws holding the VTA assembly. You have to remove the tonearm and moveable platform, and then it's trial and error how much to move the assembly.
JohnK