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Concentric pots with different values.

Discussion in 'Pickups & Electronics [BG]' started by diegom, Apr 29, 2019.

  1. diegom

    diegom Supporting Member

    I just got a new preamp for my bass. Since I can't leave well enough alone, I want to add a passive tone control. Ideally, I'd like to have it stacked with the volume. As is is common on active preamps, the volume uses a B50K pot. The perfect part for this project would be a B50K/A500K pot, which do not exist. I don't think I'm particularly skilled to "make my own", by taking apart a dual 50K and a dual 500K and swapping parts. Is there any other way I can make this work?
    Can I get a dual 500k and parallel one of them with a 56K resistor? Would the taper suffer too much?
    I'll bow to your collective expertise.

  2. okabass


    Mar 19, 2005
    I think it has high probability to work. Try it. If the taper suffers value like up to 100 kΩ may work better.
    diegom likes this.
  3. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    You can get custom pots from a few vendors. Try Banzai Music, Noll, or Potentiometers.com. Sticker shock should be a given...[​IMG]
    diegom likes this.
  4. That's strange. Which preamp is this? At 50K, the volume pot is clearly wired to the preamp output.

    So perhaps you could put the volume up front before the preamp. This way you could use an A250k or A500k pot. In this case a stacked pot is available off the shelf. And as a bonus, you'll be able to add an active-passive switch.

    It's not as hard as you think. I've done it many times in all sorts of situations over the years. In fact it's such a useful skill for bass modding, I made a video about it...

    diegom, okabass and Matt Liebenau like this.
  5. okabass


    Mar 19, 2005
    Yes. Old radios have sometimes stack pots, and I remember me doing right value stack pots that way for my Jazz Bass some 40 years ago. That was actually after I saw a photo from a stack pot JB. That was so cool that I had to make the pots, control plate and the knobs. My father had a lathe so the knobs were not a big problem. ;)
    Last edited: May 1, 2019
    diegom likes this.
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    Return the new preamp and get one with what you want on it.
    diegom likes this.
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