I own a VPI Classic 3 and just switched over from the stock 10" Classic arm to the 12" Fatboy. The problem I am having now is that the arm runs into the record weight due the angle. The VTA tower is set up for a 10" arm and needs to be adjusted to accommodate the 12". I can't find directions or videos anywhere on how to make this change. I can't be the only person in history who has gone with a 12" Fatboy! I will appreciate any help the wise men of this forum can offer me in making the proper adjustments.
Seems like the VTA tower would need to be moved to accommodate the longer arm. Just did a search and a guy on Audiogon did it a couple years ago, but sent the base into VPI so they could install a mounting plate that covers the old hole, probably like the Signature version... Audiogon Discussion Forum
Ok so the answer for future generations is this....remove the VTA tower, measure 300 mm (12") from the spindle to the screw on the gimbal, redrill all the holes, and reinstall the tower.
Just to add some more detail. VPI used to offer a kit for changing holes in an armboard/arm base. It was a drill and a tap of the correct thread diameter. Don't know if they still do, but I got mine many years ago when I had a HW-19. Maybe obvious to say, but if you do the swap yourself it helps to have access to a drill press, though I have done it with just a hand drill. On my Classic these were the steps: Remove the 10" arm but leave the VTA tower and spike installed Make a cardboard gauge that fit over the spindle with the correct 300 mm distance to the pivot point Remove the screws holding the VTA tower to the arm base Move the tower so that the tip of the gauge is at the tip of the spike Mark the position of the new VTA tower holes, then remove the arm base, drill and tap it Reinstall the arm base, then the VTA tower at its new location, and check work Remove the old pivot spike and install the 12" gimbal arm Cover the old VTA tower holes with small pieces of black tape Note that I think VPI has two types of VTA tower, one for 9 and 10" arms, and one for 12" arms; the 12" has a bigger jog in the dog leg to compensate for the longer arm length. Looking at their website (still not a very good one) it seems they still do. If you're using the 10" tower with a 12" arm there may be an issue--I say "may" because I have not dealt with this myself. JohnK
Good info John K and thanks to Guy/OP for helping me get a good deal on my newuesd 12" Gimbal Fatboy. I'll install mine later today or tomorrow. I have a Prime Signature so it should be a drop /bolt in with no fuss - hopefully.
FWIW as additional information: 1. The VPI VTA base 3-holes are spaced as an equilateral triangle (three 60-deg angles) where each side hole to hole/center to center is exactly 1.5". 2. The bolt thread size if #8-32.
Hmm, no 10" currentlyy. does that mean I have to go drilling also for the new 12"? It probably does because it doesn't fit on the setup jig properly.
If anyone is wondering....this arm is phenomenal. One of the best upgrades I've ever made. Night and day over the stock arm.
The spindle-to-pivot distance for the 12" needs to be 300 mm. For the 10" arm it's 258 mm, which is why you need to move things. Given the way the arm base is attached, you may need to contact VPI for suggestions as to how to make the swap. JohnK
@thegage Well things were working out well till I got to the end of the side and it started skipping. It's 300 mm pretty much on the mark too. I did it without the alignment jig, but just purchased it ($93) so I can have another go at it.
I've never had my Gimbal 12 skip. Check the position of the bearing housing. Because there's no locating lug you can have the outer housing rotated too far one direction or the other so that when the arm gets toward the end of the LP it hits the housing and causes skipping. Other obvious things to check, too much anti-skate, VTF is too low, or there's some binding in the bearings. Alignment should have more to do with distortion than skipping. JohnK
