Shouldn't a P-bass be completely silent?

Discussion in 'Pickups & Electronics [BG]' started by EighthNotes, Nov 28, 2013.

  1. EighthNotes


    Feb 12, 2007
    So I have this MIM P with QP's in it. I thought at one point the tone pot was going bad so I disconnected it..just snipped the wire between the two pots. Now it hums/buzzes just a bit even with my hands on the strings. Is this normal? Did I negate the ground in some way when I disconnected the tone?

    Thanks, J
  2. gidbass

    gidbass Supporting Member

    Aug 5, 2009
    generally speaking, just "snipping" wires isn't a good idea. I am going to guess that you did short something...

    luckily, it is an easy fix...;)

    Good Luck!
  3. EighthNotes


    Feb 12, 2007
    It is indeed.
  4. petrus61

    petrus61 Supporting Member

    Why did you think the tone pot was going bad? How was it behaving? As was said, its never a good idea to just go in and start arbitrarily snipping away. You likely interrupted the grounding of the circuit. Simply resolder (if capable) the old connection back with a new length of wire or if you are convinced the pot was bad anyway, just replace it with a new one of the same value (probably 250k audio) and make sure all the solder joints are good.

    Otherwise, bring it to a professional.
  5. You un-grounded it. Re-ground it. Don't just snip wires.
  6. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    There's nothing wrong with snipping wires. You do have to snip the right one however. I can't tell from your comments if you have a ton of hum which probably means you snipped the wrong wire, or if it truly is just a little hum, as you say. The tone control has some effect on the signal even when the pot is dimed and so removing it entirely might let a tiny amount of hum appear. What you are hearing may be normal if you did indeed snip the right wire.
  7. Rusty G String

    Rusty G String

    Mar 19, 2013
    If you snip the blue wire instead of the red wire you will likely blow up. I saw it in a movie. Or was it the red instead of blue?
  8. Grab the cat....
  9. EighthNotes


    Feb 12, 2007
    I was experiencing some volume loss and a very muddy, almost fuzzy tone. Eliminating the tone control was the easiest first option at the time, seems to have been the culprit although much time has passed between then n now. I can easily undo what I did, and will this weekend.

    Its not alot at all, especially compared to my Jag (those are notorious for tons of hum). But, its a humbucking pup so it should be SILENT, yes? It is a very hot pup however. That's why I'm asking if its normal. Once I resolder the wire and test the output, I will report back.

    I thank everyone for your input so far. :)
  10. Jim C

    Jim C Spector#496:More curves than Sophia + better sound

    Nov 29, 2008
    A properly set up Pbass is as quiet as anything out there.
    Buy a new pot for $5 at GC, look up the schematic online, solder it correctly (sand the plating off the back of the new pot and use flux for a good connection), and Bob's your uncle.
  11. ReidK

    ReidK Jst sy n t lsy cmprsn.

    Your approach was correct.

    Khutch is right, there's nothing inherently wrong with cutting wires. As long as you cut the wire that connects the terminals of the pots (and not the cases), you did not "un-ground" anything.

    People do seem to be forgetting that pickups aren't the only part of the bass that can pick up noise. That's why we shield control cavities... right? That fact that a bass has humbuckers absolutely does not guarantee that it will not hum.

  12. Steve Dallman

    Steve Dallman Supporting Member

    My 64 P DID hum in a lot of the venues we played in...usually when there were neon bar signs right near me. I put in a Dimarzio P that was dead silent. The P pickup went into the junk box.

    Years later, when my electronics chops had progressed, I examined the pickup. One coil had far less windings than the other. They were mismatched and that is why that one hummed. Had I known that a few years earlier, I would have either added wire to match the weaker coil, or removed wire from the hot coil.

    But I believe your problem is a wiring one.
  13. EighthNotes


    Feb 12, 2007
    Ok. Thank you for the further input, guys.

    Tonight, I've done a little experimenting. First, I wired it back to stock config. The result was the reason for this whole misadventure..muddy tone. So I disconnected the tone pot again but went one step further..I unsoldered the ground from the back of the tone pot and relocated it to the back of the volume pot, taking the tone pot out of the circuit completely. Tone is where I want it, but still a bit noisy (I'm even trying this in a different room). Looking at the diagram for the Mark Hoppus bass, which has only a single volume, there is a second ground wire going to a lug in the control cavity. COuld this be the difference? I was never aware of a circuit needing more than one ground, though my knowledge is rusty.
    Thanks, J.
  14. jim777

    jim777 Tarantula Lobbyist

    Aug 7, 2006
    South Jersey
    It's comments like that that will get us all killed!!