VPI VTA Base question

Does anyone know how to tell the difference between VPI's current JMW VTA base, and the 12" Unipivot Base?  Something visual? Or measurements? 

I can't achieve the proper alignment with my 10" Fatboy arm and want to make sure I got the correct base.



@markpao , excellent cartridge 👍

Sorry to be redundant but the best way to know if you have the correct base is to measure/confirm the actual Pivot of the tonearm (not it’s offset mount) is 258mm from center of platter Spindle.

Since you’ve measured/confirmed 258 P2S then you either have 1.) the wrong protractor or 2.) a too long out of spec armtube.

If the VPI alignment gauge fully extended so that the “v” cut-out is snug against the tonearm main pivot bearing?

Yes the V cut is adjusted to the pivot bearing the way it's supposed to be.

I can't imagine the arm being out of spec, they are all made from the same mold, right? 

I'm not new to this as this is my 4th arm I've mounted on this table, where I had to fabricate and drill a new armboard for each one. 

As far as having the wrong protractor, I contacted the vendor where I just got it and he said not likely. VPI only makes one 9", one 10" and one 12". He also said he has the Fatboy arm and his cartridge (Ortofon?) is all the way back in the headshell slots as well. This is a reputable vendor here on Agon. 

I just heard back from VPI again after sending them a few photos as requested. First off I want to make it clear that the alignment isn't that far off. From the naked eye, and photos, the diamond appears to be in the circle. Only under magnification you can see that the diamond lands on the front edge of the circle. To most that might be close enough. I can't accept that, but that's me. 

Anyway, VPI's recommendation was to either elongate the headshell holes a bit more (I won't do that) or move the VTA base out a bit. Like I mentioned above, I already thought of that and have a piece of ebony arriving soon. So a new armboard it is. I decided I'm not going out much past 258mm, just enough to get perfect alignment. 1/2 mm might do it. 

Well, time to hunker down now and get ready for Ian- supposed to hit us in SC tomorrow. Windy conditions right now.

Too bad I don't have the ebony yet, tomorrow would be a good time to fabricate and assemble. 

Make sure that when you measure the S2P distance to hold the ruler level to the platter. Is there any opportunity to borrow a Dr. Feickert protractor (or similar) from your dealer to confirm the S2P distance?