Ernie Ball JP knob question

kevin_guitars

Junior Member
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Does anyone know the diameter of the pots used on Music Man John Petrucci guitars? Not the Majesty. Are they standard CTS diameter, or 6mm alpha? Proprietary?

I’m considering getting some JP replacement knobs for a build I’m working on but cannot find any information anywhere about this little detail so I can plan accordingly what potentiometers to get.
 
They look like 1/4” solid shafts to me:


You could call and ask to confirm, or just buy them directly from MM.
 
You could always get the knobs then measure the internal diameter (or just see if it fits on a 1/4" drill bit). BTW the pot that Hodgo has a link to is an Alpha pot, but impossible to say if it's 6mm or 1/4" from the photo (they make both).
 
You could always get the knobs then measure the internal diameter (or just see if it fits on a 1/4" drill bit). BTW the pot that Hodgo has a link to is an Alpha pot, but impossible to say if it's 6mm or 1/4" from the photo (they make both).
You telling me I can’t eyeball .35mm on the internet at 6 in the morning???

Because you are right, I can’t. I didn’t realize they made 6mm solid shafts, I thought it was all metric spline stuff. My bad!
 
I tried to give it an ocular pat down to size it up. I ended up just ordering some pots from Ernie Ball to go with the knobs. $8 a piece they are surely overpriced but will be a sure thing. It's just a few buck more than if I ordered them on Amazon so no biggie.
 
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