25k dual gang stacked volume pots?

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adamrobertt
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25k dual gang stacked volume pots?

Post by adamrobertt » Sat Oct 23, 2021 10:52 am

I need to do a stacked volume/tone for a bass build. Problem is it's using EMG pickups, which need 25k or at most 50k pots. These don't seem to exist. EMG makes a proprietary version but it's $50 and I'm not going to be using an EMG preamp, so I'd like to avoid if possible.

Does anyone know of a source for such a pot?

Alternatively, I'm thinking of buying Fender 250k/250k pots and putting a 28k resistor across the outer lugs of each gang... according to my calculations, this should reduce the value of each gang to around 25k. Anyone ever do this or have any input in that regard?

Thanks!

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alexpigment
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Re: 25k dual gang stacked volume pots?

Post by alexpigment » Sat Oct 23, 2021 12:29 pm

In my experience, using resistors to change the value of pots often alters the sweep in an unpredictable (and potentially unusable) way. It's worth a try - for science, of course - but my gut tells me that the most cost effective solution is to spend the $50 and buy exactly what you need the first time.

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Re: 25k dual gang stacked volume pots?

Post by Steadyriot. » Sat Oct 23, 2021 3:33 pm

Depending on how handy you are, you can make your own!
(Allmost) all pots work the same, with a wiper running over a carbon track on the wafer. If you take the pot apart, you can switch out the wafers according to your own needs. It’s not easy (I think, never tried it myself) but doable if you’re careful. Here’s a TalkBass thread on the topic. I remember some Danelectro guys doing it too, as they used weird proprietary pots.
I’d use CTS, they seem the most accessible/modable.
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Re: 25k dual gang stacked volume pots?

Post by LVC » Mon Oct 25, 2021 11:03 am

If you're comfortable buying on AliExpress, GuitarFamily have got what you're looking for, in mini-pot format. They're a quite trustworthy seller (by AliExpress standards), and they sell mostly MIK parts.

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alexpigment
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Re: 25k dual gang stacked volume pots?

Post by alexpigment » Mon Oct 25, 2021 5:27 pm

What are the chances of an MIA knob fitting on an MIK pot?

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Re: 25k dual gang stacked volume pots?

Post by adamrobertt » Mon Oct 25, 2021 5:51 pm

Unfortunately I need to have this done much sooner than the end of November... thanks for the tip though!

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Re: 25k dual gang stacked volume pots?

Post by Sweetfinger » Mon Oct 25, 2021 9:45 pm

How many do you need?

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Re: 25k dual gang stacked volume pots?

Post by jorri » Tue Oct 26, 2021 3:55 am

alexpigment wrote:
Sat Oct 23, 2021 12:29 pm
In my experience, using resistors to change the value of pots often alters the sweep in an unpredictable (and potentially unusable) way. It's worth a try - for science, of course - but my gut tells me that the most cost effective solution is to spend the $50 and buy exactly what you need the first time.
Not unpredictable, i guess you can go and chart out every point on the pot rotation with a parallel resistor equation (or some clever-er calculus i don't know)

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Re: 25k dual gang stacked volume pots?

Post by alexpigment » Tue Oct 26, 2021 5:52 am

jorri wrote:
Tue Oct 26, 2021 3:55 am
Not unpredictable, i guess you can go and chart out every point on the pot rotation with a parallel resistor equation (or some clever-er calculus i don't know)
That's a fair point. Let's put it this way: *I* cannot predict the sweep even if I know the resistor value, whether the pot is linear/audio, and any other factors in the signal chain :)

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Re: 25k dual gang stacked volume pots?

Post by adamrobertt » Tue Oct 26, 2021 3:03 pm

Sweetfinger wrote:
Mon Oct 25, 2021 9:45 pm
How many do you need?
At least two, possibly more.

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Re: 25k dual gang stacked volume pots?

Post by jorri » Fri Nov 05, 2021 5:14 am

alexpigment wrote:
Tue Oct 26, 2021 5:52 am
jorri wrote:
Tue Oct 26, 2021 3:55 am
Not unpredictable, i guess you can go and chart out every point on the pot rotation with a parallel resistor equation (or some clever-er calculus i don't know)
That's a fair point. Let's put it this way: *I* cannot predict the sweep even if I know the resistor value, whether the pot is linear/audio, and any other factors in the signal chain :)

Imo with the thread situation it would get silly taper quickly as its around a tenth differencs of resistane between pot and resistor. Extreme S-shape.
Once you hit 10%ish on the 250k pot you half the resistance already (1/x=1/28+1/28) but that would happen on both ends (at least the volume control), while the middle doesnt really do a lot because the pot reaistance is too large in comparison e.g. (1/x=1/28+1/125)

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