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What to do about the mini pots in my CIJ 54 P-bass?

Discussion in 'Pickups & Electronics [BG]' started by timeconsumer, Nov 1, 2020.


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  1. timeconsumer

    timeconsumer

    Jul 1, 2020
    I’m looking at upgrading the pickup and electronics in my Japan-made 1954 Precision bass reissue (the one in my profile photo). However, the control cavity is only 20x80mm wide and the bass has mini pots (16mm diameter) since nothing else will fit. I’ve sprayed them twice with contact cleaner but the signal keeps dropping, so they’re not very high quality.

    What are my options here? I really don’t want to drill out the control cavity or do any other invasive mods. Are there any good mini pots out there? I’d really like the electronics to match the quality of the pickup.
     
  2. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    What's the width of a standard good pot?
     
  3. timeconsumer

    timeconsumer

    Jul 1, 2020
    I couldn’t even answer what defines a “good” pot since I’m new to guitar electronics, but from what I’ve googled it seems like a standard size pot is around 24mm in diameter.
     
  4. FunkHead

    FunkHead Supporting Member

    Mar 10, 2007
  5. Slater

    Slater Leave that thing alone.

    Apr 17, 2000
    The Great Lakes State
    Bourns and Alpha both offer quality mini pots.
     
  6. timeconsumer

    timeconsumer

    Jul 1, 2020
    Thanks, I had a look and they would definitely fit my control cavity. Will mini pots always be a compromise over standard size pots, or could I install a pair of Bourns or Alpha and be happy with the results?
     
  7. FunkHead

    FunkHead Supporting Member

    Mar 10, 2007
    They’re fine. USA G&L SB2T’s come with one(Alpha) for tone pot. They are great.
     
  8. timeconsumer

    timeconsumer

    Jul 1, 2020
    Thanks, appreciate the input. I think these will also fit my control plate without modifications.

    I found these 250k Alpha mini pots. Sorry, but what's the difference between audio taper and linear?
     
  9. FunkHead

    FunkHead Supporting Member

    Mar 10, 2007
    One’s better for tone and one for volume but I am not sure which is which. Paging @Killed_by_Death
     
    Killed_by_Death likes this.
  10. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    If you're going to 'upgrade', make all the pots 500k Ohm,
    unless you don't like the extra top-end that would give you.

    f5P1V.png

    in general, Linear taper are for Volume, & Audio/Logarithmic are for treble-cut,
    but just as soon as I post this someone from the peanut-gallery will chime in that they've always used Linear for treble-cut, or that Linear taper is not suitable for Volume.

    Audio taper is alright for Volume if you like to 'clean up' the sound by rolling the volume back a little, since it's not Linear it will 'clean up' sooner than a Linear taper.
     
    FunkHead likes this.
  11. Dominic DeCosa

    Dominic DeCosa Habitual Line-Stepper Commercial User

    Mar 9, 2008
    Winter Park, Florida
    DiCosimo Audio
    Pots come in a bunch of different sizes. The size doesn't determine the quality. You'll find a lot of quality amps and pedals using 9mm pots. It makes no difference. Just stick to a quality brand.
     
    kodiakblair likes this.
  12. timeconsumer

    timeconsumer

    Jul 1, 2020
    Thanks @Killed_by_Death , very useful! I'm aiming towards a woody, warm and organic flatwound tone, so I guess 500K would be a bit too much top end for me? I usually play with the volume on 10 and the tone either on max or completely rolled off, depending on the song. So your recommendation is linear for the volume and audio/logarithmic for treble cut then?
     
  13. arbiterusa

    arbiterusa

    Sep 24, 2015
    San Diego, CA
    The opposite. Audio for volume, linear for tone. And a 500k pot will do fine. For me, brings out the thump in flats.
     
  14. micguy

    micguy

    May 17, 2011
    500K pots give you more treble when the volume is full up, but LESS treble when the volume is not full up.
     
  15. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    500,000 pots wouldn't even fit in the controls-cavity
    :roflmao:
     
    MustangWally likes this.
  16. 250K for P bass pups. Pot tapers are identified by a letter (A250, B250, etc.):

    The A, B, C, M, N and V refer to the shape of the taper. A is a log taper. B is a linear taper. V is a Vintage taper, C is a reverse log taper. M and N are a type of sigmoid taper that are mirror images of one another (in blend pots generally).

    Taper definitions: Audio, Vintage and linear (B): 10%, 30%, 50% respectively. That tells you the percent of change when the knob is at 50% travel. My personal preference is below, but an audio taper for tone would be just fine. I use a linear taper for volume simply because I prefer it.

    For the tone cap: .022uF is more middy, .047uF is the P bass standard.

    Given the choice I would take Bourn pots over Alpha, again just personal preference. Using quality pots will certainly clean up your sound, excellent move!

    Tone wiring.JPG
     
    Last edited: Nov 2, 2020
    StayLow and Killed_by_Death like this.
  17. timeconsumer

    timeconsumer

    Jul 1, 2020
    2B1A3700-5B5F-4653-897A-EEB3370D1C57.jpeg

    @MustangWally this is awesome, thanks!

    Here’s the control cavity. The right pot says A250K. I can’t see the letter on the left pot, but I think it also says A. The cap says TK 104K. I’m going for the Bootstrap Palo Alto to replace the original pickup. I’m thinking I should just stick to 250K if the original pickup is quite bright already?
     
  18. Yeah, 250K is fine for single coil pups, at least it works for me :smug:. From your pic the right pot is your tone, which is usually Audio taper.

    Get yourself some good quality wire and do everything at the same time. I like to use the vintage cloth insulated stuff, 22awg from memory. Unless your pup is actually broken don't be in a rush to replace it - oftentimes just putting in good quality pots and wire will fix a lot of stuff all by itself. Are you OK with soldering? Lots of 'how to' videos online, cleanliness is the key. PM me if you need help.
     
  19. timeconsumer

    timeconsumer

    Jul 1, 2020
    @MustangWally Thanks, looking forward to trying it! I've never soldered before, but I'll make sure to practice a LOT before I go near my bass with the iron. :D It's good to hear that there are good mini pots out there, I was dead set on having to replace the control plate, pots, caps and even the output jack.
     
  20. Good for you, happy to help in any way I can. If you are in Houston I can come by if you want. And yeah: buy a good Switchcraft jack as well, do it all at the same time.
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    May 16, 2021

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