View Full Version : Pot shaft size?

01-09-2019, 09:36 AM
Hi fellow Pit Bullers. I've just ordered my first Pit Bull bass (a TBJ-5 ) and need to know the shaft size on the pots as I already want to change the stock ones out. Are the 6mm?

01-09-2019, 11:27 AM
Yes, sort of, but that may not be the most important thing if you are changing them out. The shafts are pretty much the same size on most guitar sized pots...around 6 mm. My micrometer says that Alphas and CTS are 6.2mm and that Bourns are 5.9 mm.

What really *is* different is the size of the threaded bushing. On most Asian pots its about 6.6 mm. It's about 9.4 on the Bourns pot I just measured. Pitbull kits come drilled for Asian pots, so the holes are 8mm (5/16"). If you want to use CTS or Bournes pots you need to enlarge the hole to about 9.5mm (3/8"). On the advice of someone on the forum I did this with reamer. I have also used a step drill bit (turning it carefully by hand--not with a drill) like this...


However, if you want to upgrade, I think the ALPS pots (Japanese) and Alpha pots (Taiwanese) are as good as US spec pots like Bourns and CTS. None of these are as good as mil-spec pots, but they are expensive and probably overkill. My EMG wiring harness uses Asian pots and it is dead quiet.

One other thing to consider is that if you change from Asian to US pots you will most likely have to change the knobs too. The knobs that come with PB kits use press on knobs, and the pots have course splines (Asian style). You can get US pots for press on knobs, but US pots have fine splines. Some knobs will work with both, but I broke one of my PB knobs trying to get it on a US splined pot.

I actually prefer to use solid shaft pots, for use with knobs that use a set screw. Both Asian and US makers have those too...but you will need new knobs. Also if you want mini pots rather than the full sized ones, I could only fine solid shafts in Bourns.

Here are a couple of pretty good articles on the differences...



Hope this helps!

05-09-2019, 10:29 AM
A timely thread given my current need.

I'm modding my mates Tokai Explorer to have split HBs via toggle switches with two volume pots as per standard and two tone pots via a stacked concentric pot.

He had purchased the pots but the threaded section of the stacked pot is too short for body mount ( OK for pickguard ) so I need to know where I can buy a dual 500K linear pot that fits the purpose, so far I've had no joy with the usual outlets including fleabay

05-09-2019, 10:20 PM
These are the longest thread concentric pots (https://guitarelectronics.com/alps-stacked-500k-dual-concentric-pot) Iíve seen, I have a couple stashed for a future project (log, not sure about linear versions). From memory, I think they require a specific concentric knob type thatís different from the CTS style etc.

Cliff Rogers
06-09-2019, 05:36 AM
Have a look at the KAISH stuff on eBay.

They have 250K & 500K in A & B.

06-09-2019, 12:57 PM
Perfect, thanks Scott & Cliff

KAISH pot ordered