P-bass tone pot question...

Discussion in 'Pickups & Electronics [BG]' started by fretlessman71, Jul 1, 2008.


  1. fretlessman71

    fretlessman71

    Joined:
    Aug 8, 2005
    Location:
    Fort Collins, Colorado
    Got a Squier P-bass with Quarter Pounder pickups. Now the tone pot is getting very scratchy and must be replaced (cleaning and turning it back and forth does little for very long).

    I'd like to be able to make an informed choice as to exactly what pot to choose and what the differences are between them (250K? 500K? Something else?), and any other simple mods that I could make that would do a good pickup justice instead of making up for what isn't there (which I suspect is a characteristic of Squier electronics). I'm apparently lousy at searching, or maybe I'm just using the wrong words to do it.

    The tone I'm going for could be described as "dark and happy"... think Jamiroquai's bass tone. (Yes I know he's not the bassist, but I can't think of his name.) I've got flatwounds on the bass which seems to be a big part of it, but I want to keep going.

    Help TBers! Thanks!
  2. fourstringdrums

    fourstringdrums Decidedly Indecisive Supporting Member

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    I can't remember the differences betweek 250 and 500k right now. I think 500k is supposed to be brighter. I don't have time to search for the answer.

    I would get a 250k pot. That is the standard pot in Precision basses. The pickup swap will make a huge difference but the other upgrade you can do is to put in a different tone cap. I don't know what you have now but .1uf is very dark and you may like that. It also has a lot of variation I found. But .047 or .050 is also good and the norm.

    *edited cap values*
  3. Mushroo

    Mushroo

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    Slight correction, .047 is the norm. :)

    250k is the standard P bass pot. 500k is recommended for humbucking pickups (that's what's in my EB-0) although some people use 500k in Fenders to get a slightly brighter sound.
  4. fourstringdrums

    fourstringdrums Decidedly Indecisive Supporting Member

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    Oh it's .047? My bad :)
  5. 60bass

    60bass Supporting Member

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    Hi

    Use CTS solid shaft pots. I think they hold up better. If your bass uses split shaft knobs, change them out. Keep the set screws tight on the knobs and they wont wiggle around which can put stress on the shaft. You might as well do all the pots and put in a quality Switchcraft input jack too.

    250K audio taper is the standard for passive Fender's. You might be able to use 500K with the Duncan's. Check their website to verify. A 500K might give you more highs than a 250K so consider that.

    If you want a "darker" sound, use a .1 tone cap which is what the early Fender P's used. Fender later switched to .05 caps to get a slightly brighter sound. Any good quality ceramic disc cap will work. When I had the QP's in my P bass, I found them to be not so dark, so if want that really dark and woody P bass tone, I'd swap tham out for a set of Lindy's or even the Fender 59 Custom Shop P bass PU's which really do sound nice and warm. For sure stay with flatwounds for the dark Fender sound. Try different types to see what you like best. I can't advise you on those as I only use RotoSound RS66 roundwrounds on all my basses.

    Hope this helps and stay low.
  6. Nighttrain1127

    Nighttrain1127

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    Near Worcester MA
    You can use either pots with just about any pickup. the Difference is that the 250k pots are darker and the 500k pots are brighter. If you are looking for a darker sound use a .060+ cap with the stock 250k pot. if you are changing out pots CTS and Alpha are good ones. Solid shaft vs split shaft I Guess what has been said makes a lot of sense when you tighten the knob screw it won't crush the shaft. I think the splits were mainly used before for the press on knobs.
  7. DavePlaysBass

    DavePlaysBass Supporting Member

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    Decimals mean a lot :)


    Orignal P-Bass cap value: 0.1uF or 100nF or 0.1mfd

    Modern P-Bas cap value: 0.047uF or 47nF or 0.047mfd


    The main thing you will get with a 500K pot on your tone control is a more coarse adjustment.

    I have a 0.1uF and a 250k on my P-bass. I like it. I roll off just a smidge almost everytime I play. It fattens things up and makes the phase change from the A to the D less noticable IME. I think the 0.1uF on a P gives me more milage than the 0.047uF on my J.

    Dave
  8. fretlessman71

    fretlessman71

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    When you say darker or brighter, do you mean at the full rolloff point? I'm assuming so, because I always thought that a passive knob turned "full up" was essentially a bypass... Is what you're saying that a 250 will be even MORE of a high end rolloff? Or does the cap have more to do with that?

    Edit: Maybe the pot has to do with the speed of the change, and the cap has to do with the amount of high end rolloff. Is this right?
  9. fourstringdrums

    fourstringdrums Decidedly Indecisive Supporting Member

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    I'd have to agree. Ever since I put a .1uf in my HW1 P I have more versatility in the tone sweep. Anyone who says a P isn't versatile doesn't know what they're talking about :)
  10. Nighttrain1127

    Nighttrain1127

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    No Pot except No Load pots are ever out of the circuit. The 250 is more tone roll off from full off to full on. The coarse/fine adjustment depends more on the pot taper Audio or Linear. Linear is more gradual and audio is more coarse IIRC. The 500K pots are brighter the same way. The Cap if I remember my electronics is a filter and controls the percentage of rolloff for lack of a better description. The Passive pots do not go to bypass. Fender/CTS has no-load pots that are bypass.
  11. Mushroo

    Mushroo

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    The 500k pot will be brighter at every setting than a 250k pot at the same setting. It's not a huge difference, though... for example, 500k with full cut is not the same as 250k with no cut. :)

    Edit: And no, the pot still affects the sound even if turned all the way up. This is why some players remove the pots from the equation and wire the pickups straight to the jack.
  12. fretlessman71

    fretlessman71

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    okay... so how do I know what kind of cap is on there?
  13. Bass Mule

    Bass Mule

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    You have to open it up. I have a MIM P w/ a SD 1/4 lb and a 500k pot. I'll probably go back to a 250k sometime, since the tone is a little too harsh for my tastes (not at all what a P should sound like IMO).
  14. fourstringdrums

    fourstringdrums Decidedly Indecisive Supporting Member

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    The Fender website parts list for the Standard P lists it having a .05uf cap. That's pretty standard. Their American Standard and Re-Issues have a .1uf cap. Like I said, the .1's are darker and I think have a wider tonal range. If you replace it you can just get a generic ceramic cap from Radioshack, but I put an Orange Drop cap in my Highway One. I got it from www.basspartsresource.com You can buy the pots there too. They are awesome in terms of speedy shipping, stock, and service.
  15. DavePlaysBass

    DavePlaysBass Supporting Member

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    If going thru the trouble of replacing the capacitor. Spend the extra $0.50 and use a film capacitor (polypropylene or polyester). They are more accurate and less noisy. You probably cannot hear the difference between them ceramics are notorious for being very non ideal capacitors with lots of variation. 10 of them, depending on the dieletric choice (X7R Y5U, et), may have a wide spread in there actual performance. X7R, NPO, and COG are the only ceramics I would consider but still go film. Its not a big deal if you are buying a new cap. And ceramic capacitors break easier than film because they're made of ceramic.
  16. DavePlaysBass

    DavePlaysBass Supporting Member

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    I think you and I are heading towards the same sweet spot. P bass with flats, high mass bridge, and 0.1uF tone. Mine is a 50's P with 760FLs and a Gotoh 201. And she can cover some ground.
  17. fretlessman71

    fretlessman71

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    So we're talking about a .1uF cap and a 250K pot, is that it? Is this the way to go?

    And another thing: What's the difference between uF and mfd? Is it the same thing?
  18. DavePlaysBass

    DavePlaysBass Supporting Member

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    Depends and who you ask and what you want.

    Advantage of the 0.1uF is that it gives a more dramatic roll off and it sound different (which is not necessarily and advantage).

    Advantage of the 250K pot is that it is a finer adjustment if you like to roll off tone than a 500K.

    Advantage of the 500K pot is that it will pass more highs (not by a whole lot) when the tone pot is full on (max treble).

    Advantage of the 0.047uF is that it will pass more highs at all positions. Maybe you will like its tone roll off better.

    You could easily experiment with two different cap values. If you solder two 0.047uF capacitors in parallel you essentially have 0.1uF. You could then clip one of the leads and have a 0.047uF. You would then remove the second 0.047uF or tack solder it back together depending on what you like better.

    uF and mfd are the same thing: micro Farad (Farad being the unit of measure of capacitance and micro implying a millionith of a Farad. A 1F capacitor is huge amount of capacitance)
  19. DavePlaysBass

    DavePlaysBass Supporting Member

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    Fretlessman. I dropped you a PM. Looks like we're neighbors.
  20. fretlessman71

    fretlessman71

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    Fort Collins, Colorado
    Got it. I went for an Orange Drop .1uF and a 250K pot. Not a bad experiment for under $6. :hyper:

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