shielding causes noise??

Discussion in 'Pickups & Electronics [BG]' started by Ben Rose, Apr 26, 2005.

  1. Ben Rose

    Ben Rose

    Jan 12, 2004
    Recently, a repairman told me that shielding in the cavities (and especially around the pickups) can cause more noise than it shuts out, acting like a big antenna.

    I'll be the first to admit that I don't know what I'm doing with bass electronics, but I don't understand why shielding would cause more hum.

    Has anybody else heard of this?

  2. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    that's a new one by me, but I'm nowhere near as experienced as some of the folks here on TB. Just wait for David Wilson or Xylion (sp?) and this will be sorted instantly!
  3. luknfur


    Jan 14, 2004

    new one on me, but it definitely can cause more problems than it resolves, depending, cause any hot contact that touches it goes to ground. It's a good idea to throw a piece of electrical tape below all pot terminal rows and between the pot and the wall anyplace where a hot pot terminal is close to the wall.
  4. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    It's ok that you don't understand this, cause the repairman clearly doesn't, either. It would be "a big antenna" if it was tied in to the positive signal. But as it's tied to ground, it's a big, well, shield. Nothing to worry about.
  5. A9X


    Dec 27, 2003
    Sinny, Oztraya
    If it's correctly implemented it will only bring about an improvement. How much that will be depends on the implementation and the size of the problem to begin with.

    There was a thread here in recently months with lots of pix of copper shielding all the cavities that look pretty good iirc.
  6. Ben Rose

    Ben Rose

    Jan 12, 2004
    Thanks for the tip. I'll try that.

    Yes, I saw that thread and have been basing my grounding on those pictures, although I haven't figured out how to create the "copper tunnel" between the pickup and control cavities yet.

    Thanks. That's a key piece of information right there. Is there anything special I have to do to make sure it is not tied in to the positive signal? Will the tip that luknfur mentioned take care of that? I have already tied it in to the ground.

    I may end up taking the bass back and trying to complete the installation myself, but my soldering sucks. Maybe I can hook up with a local electrician for a soldering lesson.
  7. A9X


    Dec 27, 2003
    Sinny, Oztraya
    Try rolling a thin copper strip into a tube and soldering it along the axial joint. Push it into the hole/tunnel and when it's in there, flare the ends to get rid of any sharp edges and to give a good contact edge to solder any other copper elements to, such as the main cavity 'can'.
  8. eots


    Dec 18, 2004
    Morris, IL.
    When tying all your ground points together, try to keep from forming a loop. Instead, tie them in to form a 'chain' as it were, then connect the shielding at one end of the chain or the other but not at multiple points.
  9. Ben Rose

    Ben Rose

    Jan 12, 2004
    Do you remove the adhesive backing from the foil before inserting it into the tunnel?
  10. A9X


    Dec 27, 2003
    Sinny, Oztraya
    I don't normally use adhesive backed sheet at all.