Discussion in 'Hardware, Setup & Repair [BG]' started by tenbellies, Apr 13, 2004.

  1. tenbellies


    Dec 17, 2003
    Whenever I let go of my bass (ie break contact with my hands and the strings) I have a very loud hum, which goes away as soon as I thouch the strings again. I am earthing the strings, or why does it do this? It is a pain when I play an open string as I have to keep my hand in contact with one of the other strings to avoid the hum? Am I electric or what?
  2. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Computer monitors, dimmable lights etc. in the vicinity and single-coils on your bass?

    Your bass is fine, it's supposed to go quiet when you touch it.
  3. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Like JMX mentioned, your strings are grounded through the cable to the amp. Is this a new bass or new amp or has it always done this? First we need to isolate what has changed.
  4. tenbellies


    Dec 17, 2003
    I think it has been there since the start, but I am starting to gig with it and it is annoying me. It is a yamaha RBX 260 (cheap and cheerful, but I love it) through an ashdown Mag. I does it even when there are no effects (Checked that).
  5. I had exactly the same problem with a Jazz Bass I customised. I was getting pretty scared it wasn't grounded properly, until I heard this, and realised that within a meter of the bass I have a laptop screen, a TV screen, and also have a dimmer light in my room! Well thanks for clearing that up! LOL :) :bassist:
  6. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Ok, lets try to isolate the problem.

    Have you tried this bass and amp in another location? Preferably another building.

    If you just plug a cable into the amp, do you still get the hum?

    Can you get access to another bass and/or amp?
  7. Sounds like a grounding problem to me. Although this could be a bad ground in the bass's electronics, it's probably wiring in your home.
    Any way you can try one of these options to isolate the culprit?
    Bring another amp and instrument to your place and try them for hum? This way you could try the other instrument on your amp, your bass on the other amp, both on your AC outlets, etc..
    Take your rig to another location that has grounded outlet plugs. Try it for hum there. Might not hum.
    Take a length of wire, and clamp (or clip) it to the metal chassis of your amp someplace, and then run it out to an outside ground pole at your place. Do not clamp it to the AC cord, plug, or any power output plugs or jacks. A screw would probably work ok, or if there is way to connect it to the metal frame of the head.

    This is what cured the same type of hum I have on a home stereo practice amp that I'm using here. Hum is gone, sound is crystal clear. Funny that I finally got around to trying it just today.

  8. pkr2


    Apr 28, 2000
    coastal N.C.
    I'd say that the ground wire to the bridge is not making good contact.

    Strip about 1/4" of isulation from a piece of wire and touch one end of the wire to the bridge and the other end to the nut that holds the input jack. If the humming stops , remove the bridge and clean the connection.

    Be very careful experimenting with chassis to earth grounds. Not only are ground loops possible, Some circuits can lose critical isolation with the chassis to ground rod scheme.
  9. As I said I experiance the same problem with my Jazz Bass copy, so I moved it away from the screens/lights and it reduced the hum significantly. However there is still a hum that is constant until I touch the metal control plate. And idea why? I'm gonna open it up and see if the ground wire is ok.....
  10. It IS some sort of a ground problem. I did the same thing. Checked out my wiring, removed the bridge to make sure the ground wire was making contact, etc.. Everything in there was OK, like I pretty-much already knew it would be.

    In my situation, I think it's the fact that my home wiring is older, and doesn't have the 3-wire wiring with the grounding wire that attaches to each outlet and gets grounded at different locations around the house.
    Newer grounded AC outlets should not pose this problem.

    If possible, you could try running a ground wire like I suggested in my previous reply. It fixed me up.