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Shielding - How do you know it will help?

Discussion in 'Pickups & Electronics [BG]' started by Killed_by_Death, Dec 8, 2017.


  1. People seem divided on this subject & I can't seem to find a resource online that would verify my thoughts on it...

    Shielding, how do you know you need it?

    IME, if the noise is being induced in the atmosphere (electromagnetic waves), then shielding will help, but...

    all possible sources of interference (within your control) should be eliminated first

    i.e. turning off all electrical devices in the area, including battery operated things, such as cellphones, computers, tablets
    turn off any UPSs that are running w/o power (on batteries)

    Yeah, if you're in the studio, you need some of this equipment, so maybe just jump straight to shielding if you've turned off all non-essential sources of noise already.

    The same would apply to gigging...

    Humbuckers aren't immune to noise, as many of us have learned.
    In this case I think the noise is a result of being induced in the wiring as well as the pickups.

    As far as 60 Hz hum goes, or dirty power, wouldn't that source easily be discounted if you ran your instrument battery-powered & disconnected from the suspected source?
     
    Last edited: Dec 8, 2017
    mobdirt and ZenG like this.
  2. Convert your practice room into a Faraday cage and connect all electrical grounds to a huge steel spike in the lawn out back?
     
  3. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
    It can only help!

    picture-72.
     
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  4. ofajen

    ofajen

    Apr 12, 2007
    92.4W 38.9N
    No guarantees it will help, but I suppose you “need” it if the induced noise in the wiring bothers you. My passives aren’t shielded, but the noise doesn’t bother me.

    Otto
     
    DiabolusInMusic likes this.
  5. Lesfunk

    Lesfunk Supporting Member

    IMG_0186.JPG I don't see why people should not agree on this.
    It works.
     
    Last edited: Dec 9, 2017
  6. Axstar

    Axstar SUSPENDED

    Jul 8, 2016
    East of Eden.
    Turning off sources of interference is a noble idea, but venues might not be so receptive if you ask them to turn off their TV, lighty uppy beer advert, fruit machine...

    I've really only found shielding to be effective in instruments where I was getting a screed of noise whenever I took my hands off the strings. Then again it is hard to describe the benefits of something that seems like it is doing nothing when it is working effectively. It is hard to say with certainty that Bass X would sound way noisier if it weren't for the shielding!
     
    DiabolusInMusic likes this.
  7. I touched on that, but I guess I should have been more clear...

    If you have a noisy instrument you're probably better off just shielding it, if you're gigging.
     
    Last edited: Dec 9, 2017
  8. jebmd

    jebmd Gold Supporting Member

    May 4, 2009
    Lothian, Maryland
    I agree it works. It will do nothing for 60hz single coil hum, but if you do it right and ground everything correctly it keeps RF out.

    692B2078-AE6C-4718-B725-845BB6677E0D. E02CF818-22C0-4B12-8FC6-AC29CA4BA646. 69740D74-BC8A-41CE-9011-0ED2351D3939.
     
  9. Vinnie Boombatz

    Vinnie Boombatz Banned

    May 26, 2010
    If you're having issues with RF interference and you shield it correctly, it will work!

    I personally like the paint. I found this stuff...

    9YNKRDb.

    ...and have been pleased with the results. I also have a roll of copper foil, but the paint is way easier and faster, in my opinion. I guess the negatives are it's a touch on the expensive side at $15 for a really small 20g bottle, but you could get 1.5, MAYBE 2 Fender-style basses shielded from a bottle. But you can get a much larger 250g can for like $32, which is a much better value, especially if you have multiple basses. Just make sure you shake the bottle often to keep the metal particles from settling. It also smells pretty bad/strong, but if you don't put the pickguard back on right after painting and let it air out for several hours or a day would be even better, it's not that bad. Then ground it properly and you're all set. I just soldered a piece of wire to one of these (ground ring terminal)...

    EgTiVKJ.

    ...then just used a Fender pickguard screw and anchored it into the shielded cavity, then slapped a quick coat of paint over the screw and ground ring terminal (the coat of paint over the screw and terminal probably weren't necessary).

    I did this to my Classic 50's Precision and it's DEAD QUIET. Definitely had noise before, and now it's gone. Just understand that this is NOT, as others have mentioned done to get rid of 60 cycle hum. My G&L JB-2 Tribute was already had painted cavities, so I just grown dad it properly. IT has VERY hot pickups so you get a noticeable 60 cycle hum, otherwise, again, it's dead quiet.
     
    Last edited: Dec 14, 2017
  10. My P/J Jaguar had a hum when I first got it. I shielded it wlth copper. Now its super quiet.
     
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  11. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    To make a bass quiet in almost any electrical noise environment, it needs to have both humbucking and shielding. They are two different things. If you only have one of them, you will get noise in some situations. The techniques of humbucking and shielding are well known and proven. I'm not sure what your question is?
     
  12. Humbucking pickups have taken care of noise problems for me at home, except in the case of the Mexican Fender Blacktop.
     
  13. SoonerBill

    SoonerBill Supporting Member

    Aug 27, 2017
    That could create a ground loop problem. You would need to first make sure that the grounding system of your building electrical system is good and then connect your Faraday cage to that. Over the years I’ve seen ground loop problems do some really odd stuff.
     
    ZenG likes this.
  14. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    if your problem is extra noise that happens when you let go of the strings, then shielding will help.
     
  15. So if the noise doesn't go away by touching the strings (with a grounded bridge) then shielding won't help?
     
  16. One of the main problems with copper shielding tape - the self adhesive stuff - is that people do not use it properly.

    In the main, guys stick pieces inside the control cavities using as many pieces as fits the cavity (which, of course, is exactly correct). They then assume they have shielded their bass. But they haven’t. This tape has an adhesive layer on the underside ... which is great for sticking it inside the cavity, but rubbish for making an electrical contact between it and adjacent pieces of foil.

    In other words, the control cavity comprises a number of copper foils **that aren’t connected together** at all. They’re electrically separate and therefore aren’t earthed.

    To get around this I’ve bridged two or more foils with a small blob of solder. Every time one foil overlaps another I go along the join line and make a small soldered joint - say, every inch or so.

    If there are control cavities that can’t be joined electrically, I run a piece of wire from the shielding to (what’s known as) a star earth: this star earth ultimately gets joined to the jack socket earth (signal low) point.

    Shielding is a complicated electrical subject. It’s also one that is changing for musicians. At one time, only mains frequency noise (hum) was an issue. But now, with digital systems everywhere (amps, effects boxes, etc) that part of the noise spectrum could start to be an issue. In that case, copper foils will need to be well bonded to keep radio fields away from on-board wiring, and pickups may need to be build in shielded boxes - like the familiar chrome or brass enclosed pickups we see on many guitars.

    RJ
     
  17. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
    Right on. The copper foil is sold as having conductive adhesive, but a quick check with an ohmmeter shows that to be optimistic. Spot-soldering adjacent pieces is a wise approach.
     
  18. tlc1976

    tlc1976

    Aug 2, 2016
    Michigan
    IMO, it's if the bass isn't shielded. It's easy enough to do, can be done for next to nothing, many times makes a difference and if not, it hasn't hurt anything. I'd rather just do it and have the best possible chance of a quiet bass. Rather than say no problem it's quiet in the home practice room, then have it make a ton of noise when I take it somewhere.
     
  19. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    I stopped using copper tape for shielding on my basses many years back because it's too unreliable. The problem is that the adhesive on the back isn't very strong to begin with, and it dries out and lets go over time. Pieces of tape, particularly on the side walls of the cavity, come loose over time. They lose electrical bond with each other, and can curl in and contact lugs on the wiring, shorting things out. Unless the side walls of the cavity are carefully sanded and finished smooth (which is a lot of work), the tape won't stick well to the routed wood side grain.

    When I was using copper tape, I'd always cover it with a layer of clear packaging tape. That would help keep the overlaps stuck together, and provide a layer of insulation so that nothing could short against it.

    In recent years I've been using SuperShield nickel spray shielding. Fast and simple and absolutely reliable over time.
     
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  20. tlc1976

    tlc1976

    Aug 2, 2016
    Michigan
    When I shielded my first 3 basses over 20 years ago, I used aluminum foil and glue stick. When I recently rewired the Ibanez, I noticed that foil is still holding up excellent.

    I haven't used the copper tape, but I'd imagine it's similar to the super sticky aluminum HVAC tape. When I shielded my 2 recently acquired basses, I used the HVAC tape. I noticed the same thing, it does not want to stick very well to a cavity rout that isn't super smooth. I'll have to check it later, and rip it out and do it how I did the others if need be.

    I'm guilty of layering foil or tape and not checking whether or not the conductivity is present throughout. But in any case, the shielding I did is a night and day difference compared to no shielding, the basses are quiet, never seen any ill effects, so I'll keep running with it.
     
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