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conductive sheilding paint

Discussion in 'Pickups & Electronics [BG]' started by dougray, Oct 30, 2004.


  1. dougray

    dougray Supporting Member

    Apr 16, 2002
    western maryland
    i recommend this stuff! :D
    i have 2 basses that #1-picked up an AM radio talk show,lol. #2-bass when i moved or turned made loud cracking sounds. i purchased the sheilding paint(stewmac).after disassembling everything i applied 3 coats,letting each coat dry completely.i even removed the foil backing on the cavity cover and applied 3 coats to that. all i can say is now both basses have zero noise! :bassist: great product! :hyper:
     
  2. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    I've never used the paint but I used the foil shielding and wouldn't use the foil again except on the floor of the control cavity to eliminate having to run ground wires. The floor's no problem but the sides are a pain and time consuming. The foil is also a problem regarding shorts as any hot lead (pot lug, whatever) that touches it goes to ground.
     
  3. slowburnaz

    slowburnaz

    Mar 27, 2002
    Tucson, AZ
    Hmm... I might have to look into that. I just had a Geddy Lee jazz bass modified by a shop. I had them do the parallel/series push-pull pot modification. It didn't buzz before, but now it buzzes like mad. If I touch the control plate, it goes away.

    Is this a problem with grounding?
     
  4. dougray

    dougray Supporting Member

    Apr 16, 2002
    western maryland
    yes that sounds like a possible grounding prob. ,check all connections, and could possibly be a "cold solder joint",bad control(pot),bad jack,cord,etc.
     
  5. slowburnaz

    slowburnaz

    Mar 27, 2002
    Tucson, AZ
    Well, the only things that have changed are the pot (push/pull instead of standard) and the wiring/soldering involved. Looks like I'll be taking it back to the shop...! :hyper: :crying:
     
  6. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    The paint does work, but I know for a fact that luthier Michael Dolan does not recommend it because over time the paint does not always hold up. The foil is superior even though it is more difficult to apply.
     
  7. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    if you use foil definetly throw a piece of electrical tape beneath each set of pot lugs and along the walls wherever the lugs may be close. That's what I did cause I wasn't about to rip it out after spending the time to put it in. And be sure any battery terminals are prevented from contacting the foil. I just use a piece of thin foam padding extending at least to the outer edge of the clip. With some clips the terminals are protected by design but I wrap the battery regardless.

    Even Sadowsky warns you about shorts that can occur through the use of foil even though he recommends foil shielding all cavities.
     
  8. dougray

    dougray Supporting Member

    Apr 16, 2002
    western maryland
    personally, i dont see how the sheilding paint would ever come off? when i was applying it,i left some dry on my finger,man it was he*l getting it off,it even says on the can water clean up until it dries... its a permanent application..:bassist:
     
  9. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    I don't have an answer to that question, but I do know that Michael Dolan advises against using it. I respect his opinion greatly as he has many years in the business as both an independent luthier and a former Alembic employee.
     
  10. chapito

    chapito

    Aug 26, 2008
    New York
    Can anyone describe the appearance of shielding/grounding paint?
    Once painted, is it like a black graphite, slightly chaulky?

    My bass has a graphite chaulky paint beneath the pups and I was wondering if it had already been shielded

    Can I foil tape over it, or clean it out first?

    Thanks
     
  11. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    The paint will do the same thing.

    I'm working on a Pedulla that had the output jack shorting to the paint.
     
  12. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    Yes, that's what it looks like. The problem with many factory basses is they paint the stuff on, but then don't have any connection to ground. The control compartment will be grounded, but often the paint under the pickups is not, and that wont act as a shield.

    You can put foil over it, but it might not stick well.
     
  13. chapito

    chapito

    Aug 26, 2008
    New York
    If I were to use the original fender grounding strips (70s Jazz) touching the paint, that would ground the paint, right?

    so.. Pickup/ground plate *touching* paint -> ground
     
  14. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    That should work fine.
     
  15. I use foil for the back of the pickguard. I use star grounding. I use 2 coats of Shielding paint on the bridge route and all the pickup and control cavities. Just make sure that your reading 0 ohms from any area that is shielded.

    If your going to use foil. I would recommend soldering the overlaps.
     
  16. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    The copper tape has a conductive adhesive, so you don't need to solder the over lap, but it doesn't hurt.

    Star grounding doesn't perform any function in an instrument.

    Also, always use a wire for the bridge ground. The paint has a resistance, and you want a low resistance path to ground.
     
  17. chapito

    chapito

    Aug 26, 2008
    New York
    I hear some don't like to ground to the bridge to reduce risk of shock with bad AC in unknown venues etc...

    http://www.guitarnuts.com/technical/electrical/safety/index.php

    Personally, I want my bridge grounded but with touring and playing around different clubs, it caught my attention.

    whats your take?
     
  18. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    You will get a lot of noise without the strings grounded. You can do it if you use EMG pickups, because they have built in faraday cages. I got away with not grounding the bridge on a bass that was extensively shielded, but it's difficult.

    To reduce shock hazards use a cap between the bridge wire and ground. HAS Sound sells a "Zap Trap Safety Circuit" that is pretty cheap. It's probably a cap and resistor network.

    My opinion of Guitar Nutz is a lot of the information there is flawed. Take it all with a big grain of salt. For example, you cannot have a ground loop in a bass or guitar. It's not possible. There is only one ground source... the output jack. Ground loops occur when you have two pieces of AC powered equipment on two different circuits with different grounds, and you plug them together. Then you get current flowing across the ground because one is at a higher potential.

    No grounds inside you bass are any different from any other. It's all a big ground plane.

    The surest way to avoid shocks is either transformer isolation, or go wireless. I've gotten a few really bad shocks over the years... it's not fun! I used to carry a small neon outlet tester with me. I'd touch it between the strings and the mic, and if it lit up, there was a problem with the grounds. Usually switching the ground switch on the amp helped. Sometimes I lifted the ground with a three to two pin AC adapter. But that's risky.
     
  19. chapito

    chapito

    Aug 26, 2008
    New York
    Thanks SGD Lutherie,
    I haven't had a ground (shock) issue, and I'm using quality equipment so I'm not too worried. But after finding threads and sites talking about it I thought I might be missing something. Thanks for the clarification.
     
  20. Actually, I'd like for someone to expand on this a bit more or to point to a link with Absolute Truth(tm) on it, particularly in reference to cavity-shielding to reduce noise.

    I have a Warwick with EMG/JJ & a BTC that I just cleaned up a noise issue with by re-soldering and using shrink tubing, but I've never been entirely sure what to do with shielding. The noise on the Wick is NOT gone, just reduced and doesn't pick up AM radio anymore.

    I have had the string<->mic issue before, particularly on cement & linoleum floors! In fact, I've been shocked so bad before that I used to snip the bridge ground on my passive basses before I ever plugged them into my rig. Most SS amps don't come with a ground lift switch... least they didn't used to.

    "*bzzzt* OMG I hope I can still have kids!"

    --G