Concentric pot(s) question:

[madjazzbass]

Does anybody know what the difference is between a A50K Concentric Stacked Dime Size Pot and a B50K Concentric Stacked Dime Size Pot?

 

[dwizum]

A and B are the tapers. A is audio, B is linear. If you see a C it's usually reverse audio. Some brands put numbers after the A to indicate a specific shape other than log, i.e. A2 might be slightly steeper than A1 etc - in those cases you can check the datasheets to see.

Blend pots have their own indicators for their sometimes whacky tapers too...

 

[MPU]

... and then there's this idea: ... "All you need to do is bend back the 4 tabs on top of the donor pots and remove the wafers and swap them with the wafers in the stacked pot you started with!"

Yes IF all the pots are from same maker and same series. I’ve done it and it can be very, very time consuming to search the parts.

 

[madjazzbass]

Thanks, that helps a lot; You are wise beyond your years

 

[Killing Floor]

I think what you're asking is "How can I get a John East J-Retro Preamp?"

 

[Passinwind]

Yup it'll work fine if you get a stacked pot with the same values as the two you're replacing.

Note that this preamp already has a concentric pot for treble/bass. So you can't stack those, they're already stacked. It's unusual to find a concentric pot with one position as a blend pot (since blend pots have two separate circuits in them). So you can't stack that blend pot. And there's an active/passive push/pull on the volume pot, which is unusual to find for a concentric pot as well, so you probably can't stack the volume pot.

You might want to take a look here: Potentiometer / noll electronic

Fitting some of those configs into something like a Jazz bass can be a bit of a challenge though, IME.

 

[JKos]

@madjazzbass ,
Look for any labelling on the two pots you want to combine. What do they say?

Something like A250K or 50KB.

- John

 

[lokikallas]

The EQ pots most likely have a center detent, VS. the passive tone without. I've never seen a stacked pot with one of each.

 

[StayLow]

Suggestion: Probably easier to drill a hole for the toggle.

Good luck with your project.

 

[madjazzbass]

@madjazzbass ,
Look for any labelling on the two pots you want to combine. What do they say?

Something like A250K or 50KB.

- John

Hey Thanks, That's the problem, I don't have the preamp yet, so I don't know what the values are that I want to combine

I think what you're asking is "How can I get a John East J-Retro Preamp?"

Yeah, pretty much, but I'm on (like The Kinks say) a 'Low Budget' ... WHAT DID YOU SAY?!

 

[madjazzbass]

Suggestion: Probably easier to drill a hole for the toggle.

Good luck with your project.

Nah, That hole is already there, the plate has 4 holes (using the input jack hole) and 1 mini hole for the switch/toggle.

 

[eottjake]

Can you find that pot anywhere as an individual part?

I'll take a look tonight when I get home