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Some help, please, on using aluminum tape for shielding

Discussion in 'Hardware, Setup & Repair [BG]' started by dryheatbob, Jan 8, 2004.


  1. Hey, thanks for dropping by! :D

    Here's what I've got going on:

    I'm about to put my Hamer Cruise back together after refinishing it. I planned on shielding the control cavity using aluminum tape, and now I've come up with some questions after searching the setup forum on shielding.

    First off, is shielding necessary when there wasn't any in it before and the bass was quiet? It's got single coil jazz pups and is passive. the control cavity and pup cavities had a black paint in them, but I doubt it was shielding paint. Is shielding this bass overkill? What would I be gaining?

    If shielding turns out to be a good(or necessary) idea how do I ensure that the sides and bottom of the cavity have good continuity(conductivity? sorry, I'm not sure what the proper word is) since aluminum tape can't be soldered? I know the tape on the sides and bottom need to overlap- is that all I need to do?

    What's the best way to ground the aluminum tape? I saw a thread that said to solder a ground to one of the pots and screw that wire into the shielding and another web site suggested screwing a wire into the shielding and running that wire to the bridge. Running a wire to the bridge seems the easiest to me, but if grounding the shielding to a pot is better, I'll do that.

    It just occurred to me that a third(and far easier) way would be to screw the existing ground that goes from the tone pot to the bridge to the shielding instead. Will that work or do I need both grounds(to the bridge and the shielding)?

    As far as gounding goes, should I be careful to not let the pots ground out to the shielding? I mean should I cut the shielding back so it doesn't come in contact with part of the pots that bolt through the front of the bass?

    I should mention that I salvaged the old pots and wires by snipping the pup wires and leaving the rest of the wiring alone. Everything worked fine so I saw no reason to to tear apart what wasn't broken.

    If I shield the pup cavities, I'm figuring I'll also need to ground these. Any suggestions how to do this neatly given the small space to work in? Especially the bridge cavity- I can't for the life of me figure out an easy way to put a ground wire in that little hole without messing up how the pup fits in it.

    A search of the forum turned up alot of great info, but the threads I found didn't really answer these questions, so here ya go!

    Thanks alot guys

    Bob
     

  2. First off, is shielding necessary when there wasn't any in it before and the bass was quiet? It's got single coil jazz pups and is passive. the control cavity and pup cavities had a black paint in them, but I doubt it was shielding paint. Is shielding this bass overkill? What would I be gaining?


    Shielding isn't necessary if the bass was suitably quiet before refinishing. The black paint most likely IS shielding paint since simply painting the cavities black is too labor intensive not to have another function. This might be the exact reason the bass is so quiet.

    If shielding turns out to be a good(or necessary) idea how do I ensure that the sides and bottom of the cavity have good continuity(conductivity? sorry, I'm not sure what the proper word is) since aluminum tape can't be soldered? I know the tape on the sides and bottom need to overlap- is that all I need to do?

    The adhesive covering the overlapping areas will keep the two layers from making contact. What I do is to use a sharp metal tool to punch through both layers and make a little "rivet". You'll probably have to do several in different places to get good conduction.

    What's the best way to ground the aluminum tape? I saw a thread that said to solder a ground to one of the pots and screw that wire into the shielding and another web site suggested screwing a wire into the shielding and running that wire to the bridge. Running a wire to the bridge seems the easiest to me, but if grounding the shielding to a pot is better, I'll do that.

    The best grounding method is the "STAR" method where each component (bridge included) is grounded to a single point. You'll automatically ground your shielding by putting the pots back in. The shoulder of the pot will contact the shielding.

    It just occurred to me that a third(and far easier) way would be to screw the existing ground that goes from the tone pot to the bridge to the shielding instead. Will that work or do I need both grounds(to the bridge and the shielding)?

    It would be better to directly connect the bridge ground to the pot rather than running through the shielding. The STAR method dictates the same length path to ground for all components.

    Hope this helps.
     
  3. Thanks, Hambone!

    In respect to star grounding, does your advice include running a ground from the pups? If it does, I'm assuming it would have to be added to the pup, that the pups' original ground still needs to be soldered to the pot. Is this correct?

    Bob
     
  4. Yes, any ground that is part of the pup wiring should be attached also.

    Dang, where's Merls or Pkr2 when we need 'em??
     
  5. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    I'm sure not needed here. Great advice and great explanation , Hambone.
     
  6. Thanks for the info, guys!

    Too many on call patients this weekend to finish rubbing out the paint on my Hamer, so it looks like I won't be able to put your advice to work until Wednesday or Thursday. Man I want to play that bass again!

    Bob
     
  7. WarriorJoe7

    WarriorJoe7 Banned

    Mar 12, 2004
    Syracuse, NY
    Why are star grounds better than other grounds?
     
  8. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Instrument Technician, Club Bass and Guitar - Toronto
    Star grounds insure that there are no ground loops. When there is more than one path to ground, ground loops are formed with associated noise.
     
  9. true...and if you can produce an appreciable ground loop within the confines of a bass control cavity, you've done something significantly incorrect...

    in other words, star grounds inside a bass is overkill...
     
  10. AlembicPlayer

    AlembicPlayer Im not wearing shorts

    Aug 15, 2004
    Pacific Northwet, USA
    use aluminum tape with conductive adhesive

    just sayin