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Almost finished, need reassurance

Discussion in 'Pickups & Electronics [BG]' started by Motoboy, May 24, 2005.

  1. Motoboy


    Nov 21, 2004
    Greer, SC
    My Warmoth P-bass project is almost finished. However, I am worried about my wiring. I tried to follow the advice of the guitarnuts.com star-grounding, but if I read correctly, it only includes one capacitor. It is from either pot to ground. Does that sound right? It seems to me that the tone pot requires one from the tab to the volume pot, not from the case to ground. Should I add another cap like the one in all the factory wiring diagrams, or finish assembly as-is and see what happens.

    Know this: I am an electronics moron.

  2. You only need one capacitor if you're only using one tone pot.

    I'll assume that your P-bass has a standard single volume, single pot wiring setup?

    The role of the tone capacitor is to bleed some of the high frequencies to ground (thereby cutting tone) ;) and you only need one capacitor per tone pot. For example, on my P bass I have one volume and one tone and only one capacitor....on my Corvette with J pickups I have it wired with a volume and tone pot for each pickup. In this case I have a capacitor on each of the two tone pots.

    The capacitor would normally be wired from one of the outside tabs of the tone pot to the back case section of your pot, as the case of the pot should be a ground source.

    It doesn't matter which of the outside tabs you use for the cap to attach to, choosing a specific side will decide which way you turn your pot to cut tone. For example, if the tone pot tabs are numbered 1, 2, 3 then if you use tab 1 you'll get to turn the tone pot one way (say counterclockwise) to cut tone, and if you use tab 3 your tone pot will cut tone by moving it clockwise.


    Good luck ;)
  3. Motoboy


    Nov 21, 2004
    Greer, SC
    Thanks! I am only using one volume and one tone.

    I put the capacitor on a large ring connector around the threads of the volume pot to the star ground. I think it's just for shock protection. Will it adversely affect volume or tone?

    I can then add a second cap like you suggest? Or should I eliminate the first cap?

    An avionics guy just suggested running the tone cap from the outer tone tab to either of the hot tabs on the volume pot, switching back and forth to see which sounds better. Does that make sense too?

  4. The cap you're talking about sounds like a treble bleed cap on the volume pot, which IMHO is quite unnecessary for a P-Bass. It's role is so that as you turn the volume down, your tone stays the same throughout the volume curve. And I'd say it'd be more often used in guitars than basses...

    Personally, I'd eliminate the cap you've suggested, and run one single cap from an outer leg on your tone pot to ground ;)
  5. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    The cap mentioned on guitarnuts is not a tone cap, but a way to prevent you from being shocked. Wire it up like it says on guitarnuts, then wire the tone cap as found in countless schematics.
  6. Ahh...sorry, my bad - I should have gone and looked at the site in question, yes Lyle is right, the 400V Cap mentioned is there to offer you protection if you ever plug into a malfunctioning vintage amp, and not a treble bleed circuit as I first thought you meant...add it if you like, but still go ahead and add the tone cap in addittion as I described.



  7. Motoboy


    Nov 21, 2004
    Greer, SC
    Thanks. But I have more to worry about than just the cap.

    I finished assembling the bass last night and it looks fantastic. Unfortunately, I plugged it in and got the worst series of pops, hums, howling and sonic garbage imaginable! I did something wrong somewhere.

    I tried a little rerouting of the pots and ungrounding some stuff, but to no avail. Tonight I'll pull the pups to see if I accidentally grounded the hot wire to the shielding. After that...? Maybe I'll take it to an expert.

    It sure is beautiful, though!

  8. First you should check and make sure you didn't wire your output jack backwards. That's comon and will make lots of noise.
  9. Motoboy


    Nov 21, 2004
    Greer, SC

    It's been awhile. I got frustrated and just put the bass away for awhile to work on my bikes. I actually bought an SX to play during the interum.

    Now it turns out that Searcy was right! I reversed the jack leads, and it sounds beautiful! Thanks! :hyper:

    I'll post pics soon.
    Thanks for your help on my first bass.


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