Modifying Pot Value

Bezmotivnik

Bezmotivnik

New member
I have a factory stacked tone control that is 1M (POS Danelectro, naturally), which is too high for working a lipstick pickup, which is typically 250K. It doesn't work.

I can't replace the ganged pots, but I've been told that by placing a resistor across the pot terminals, the overall resistance can be reduced, though the taper may be a bit screwy.

Does anyone know how (or if) this is done and what value of resistor will knock a 1M pot down to around 250K?

Yes, I know I'll have to swap the .1mFd cap for a .022mFd.

Thanks for any clear answer to this specific question.
 
Re: Modifying Pot Value

1 meg resister and 1 meg pot,gave me a reading of 524k.

500k pot....1 meg and 1 meg in parallel gave me exactly 250k.

for your 1 meg pot to 250k try a 2.2m resister,or a 3m and see where u are.
you can also combine resistors too,to get it at exactly 250k if your a picky bastard,i know i am.:lol:
one thing,make sure you test your pot,even if it says 1m it may not be,some of mine were 860,870k
 
Re: Modifying Pot Value

There is a way to figure this out:

1/(r1) + 1/(r2) = 1/(r3)

Basically, r1 is 1 meg (1000k), the value of the pot you have now. r2 is the resistor you need to modify it, and r3 is the value you want, 250k. Do the algebra here, and we get: 333k resistor. You can likely easily find a 330k, next step higher would be a 360k. Of course, you can do a little more math and dial it in a bit more. The 330k ought to get you in the ball park, though.

I will warn you, the taper will be real out of whack at that point, but it's definitely worth a shot to see if it's something you can work with. The further you modify the pot with that resistor from it's original value, the odder the taper will become.

BTW, you can get 250k stacked pots with those wacky Danelectro concentric knobs at places like AllParts: http://www.allparts.com/250K-and-250K-Concentric-Pot-p/ep-4485-000.htm

Old Jazz basses(like the 62's) had concentric volume and tones, with a 250k/500k dual pot. Those aren't hard to find either.
 
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Re: Modifying Pot Value

black sunshine said:
1 meg resister and 1 meg pot,gave me a reading of 524k.

500k pot....1 meg and 1 meg in parallel gave me exactly 250k.

for your 1 meg pot to 250k try a 2.2m resister,or a 3m and see where u are.
Click to expand...
How evenly does the resistance roll off as the pot is turned down?
 
Re: Modifying Pot Value

trevorus said:
I will warn you, the taper will be real out of whack at that point, but it's definitely worth a shot to see if it's something you can work with. The further you modify the pot with that resistor from it's original value, the odder the taper will become.
Click to expand...
Yeah, that's what I figured, but I thought it would be worth a shot. The tone controls don't work at all the way they come from the factory.

Danelectro instruments are such appalling crap, I swear.
 
Re: Modifying Pot Value

Bezmotivnik said:
Yeah, that's what I figured, but I thought it would be worth a shot. The tone controls don't work at all the way they come from the factory.

Danelectro instruments are such appalling crap, I swear.
Click to expand...

That is part of their charm. They look like they were built in a garage by a stoned kitchen counter installer while watching the Jetsons. And they sound phenomenal when set up properly. Good luck with it. Danelectros have a special place in my heart.
 
Re: Modifying Pot Value

Heres some info on this subject if it's any use.

bending-the-law-of-resistance2-ewww-091201.jpg


bending-the-law-of-resistance1-ewww-091201.jpg
 
Re: Modifying Pot Value

Danger, GV, that is an awesome find! I'm definitely saving that to print out to use later!
 
Re: Modifying Pot Value

If the 1 Mohm doesn't work at all something else is wrong. Has nothing to do with the rating.
 
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