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.



Remove the arm and measure spindle center to pivot spike. It should be 258mm.  The 12” is 300.

I have the proper P2S distance. The cartridge is pegged to the rear of the headshell slots and it needs to go back a bit more. 

Just trying to find out if I got the right base at this point.

If the VPI forum is still active, might be worth searching. Reaching out to VPI is in order too.

Are you using the VPI protractor? If so, it's supposed to be a distance that's somewhere between Stevenson/Baerwald. If you have an aftermarket jig, perhaps try Baerwald, which might push the cart more forward?

I've read random reports some cart brands for whatever reason just won't cooperate with any amount of fussing.

Thanks for the response's so far........

but back to my original question- can anyone tell the difference between the 2 arm bases? Something visual or something I can measure? Visually they look the same to me on VPI's website.

I recently acquired what's supposed to be the JMW VTA and I want to make sure I got the right one before too much time goes by.

I do have an email into VPI, but the site says may not hear back from them for 3 days.




If you are using a vta tower designed for the JMW 12 series tonearm on a table that typically uses a JMW 10 tonearm, and you use the original JMW 10 mounting holes for the JMW 12 vta tower, you will not be able to get the correct 300mm S2P distance without remounting the vta tower.


The VTA 12 has a larger dog leg platform than the VTA 10

I got confirmation from VPI that I do have the correct JMW VTA base. I'm just puzzled as to why I can't get the proper alignment when I have the correct P2S distance.

Right now I'm using the VPI jig and the diamond is at the forward most part of the circle, almost just off of it, with the cart as far back as it will go. I know it's close, but it's not right on, and leaves me no room for tweaking. I do plan on getting a Mint protractor soon and I'm sure there will be more adjusting to come.

The only solution I can come up with is to remount the base for a P2S distance of 260mm (2 mm over). At that point I should be able to pull the cart forward to achieve a good alignment. I have a piece of ebony on its way. 

I'm still open to other suggestions, if anyone has one. 




I see you replaced an “original” jmw 10” arm. If you are using the vpi jig for that arm it’s for a p2s of 250 mm and a true 10” arm. The fatboy 10” is actually 10.5”. Could that explain your situation?

My alignment results are from a brand new VPI 10" jig I just ordered along with my new arm and base. 

What cartridge are you using?  Some long body cartridges can be problematic. 

@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?

,,just a silly question.....are you sure you have the pivot spike on the proper pivot.   I know If not careful, I can move my arm to another spot.   The correct spot has a metal insert and properly set up will allow the arm to tilt (azimuth) easily

Yeah, I must have pulled measurements and reset the arm on the pivot a hundred times over the past week.

I know what you mean stringreen, at first setting the arm down on the pivot felt a bit awkward compared to my older version. But you know when it’s on right, and it goes on easily now that I'm used to it.



My original (1995) jmw 10 has the arm pushed into the bell housing for a friction fit.  It can be less than seated and feel secure. The Fatboy looks similar.  Maybe get half a mm?