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This is a Shielding Issue, Right? (Nordstrand Pickups / Preamp)

Discussion in 'Pickups & Electronics [BG]' started by Modern Growl, Nov 9, 2012.


  1. Modern Growl

    Modern Growl Supporting Member

    Joined:
    Jun 7, 2005
    Location:
    NY/NJ Metro Area
    I'm pretty sure this is a shielding issue, but wanted to confirm you with you guys.

    Passive Nordy Pickups
    Active Nordy 3b-4a Preamp
    Conductive Paint Cavity (Factory Paint, Warwick Germany) < probably the issue - although when everything is all wired up and connected, when I touch the shielding paint with my finger, the noise goes away too... so my guess is the paint is connected to ground, but it's a week "shield"... and that I need to take an hour or so and bust out the copper...

    Everything works great - but I get some Buzzing when not touching ground with my fingers. Without touching the strings (bridge, etc... anything metal connected to ground) - I get a slight buzzing. When I touch the bridge, strings, or any of the pots inside the cavity - it goes away.

    Thoughts? Bust out the copper shielding?
     
  2. megafiddle

    megafiddle

    Joined:
    May 25, 2011
    The fact that touching the shielding paint eliminates the noise would indicate
    that it is grounded. But it would also indicate that it should be effective as a
    shield.

    Is there any difference depending on your relative position? Is the buzz stronger
    when it's in the normal playing position? Or is it worse if the bass is turned so that
    the string side is facing you (without touching anything grounded)?
    That could indicate where shielding is needed.
     
  3. Modern Growl

    Modern Growl Supporting Member

    Joined:
    Jun 7, 2005
    Location:
    NY/NJ Metro Area
    I think the shielding is uneven... I'm just going to open her up and spend some good ol' time making her shiny & copper.
     
  4. Modern Growl

    Modern Growl Supporting Member

    Joined:
    Jun 7, 2005
    Location:
    NY/NJ Metro Area
    Alright - well that was frustrating... I just spend a good time shielding the entire cavity and connected to ground and I'm still getting the buzzing.

    :mad:
     
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  6. DieterVDW

    DieterVDW

    Joined:
    Sep 19, 2012
    Location:
    Gent, Belgium
    Probably your amp is not plugged into a grounded outlet.
    I have this too, no grounding in the outlets in my appartement :( .

    If you can, try plugging it into a grounded outlet and you'll see the noise disappears.
    If anyone has a solution to this, let me know!
     
  7. Modern Growl

    Modern Growl Supporting Member

    Joined:
    Jun 7, 2005
    Location:
    NY/NJ Metro Area
    No... I have 4 basses and all the others are dead silent. No grounding issue with my home electric either...
     
  8. Modern Growl

    Modern Growl Supporting Member

    Joined:
    Jun 7, 2005
    Location:
    NY/NJ Metro Area
    Here is a shot of the shielding job:

    [​IMG]
     
  9. Means2nEnd

    Means2nEnd Supporting Member

    Joined:
    Jun 27, 2010
    Location:
    somewhere between York, and Lancaster PA
    I’m assuming the bare ground wire from the bridge is now soldered to the copper shielding? Even the supposed conductive adhesive shielding tape needs to be soldered where is joins pieces. I would bet money it’s none of those things. You must eliminate one thing at a time. Make sure none of the tabs wires are soldered too are touching the shielding. Even one small hair of wire will do this. Did you wire a ground between all pots? Only one wire to the main ground at jack not more than one?

    For sue it is a wire or pot that touching or not grounded well or something like that.
     
  10. David Jayne

    David Jayne

    Joined:
    Jan 16, 2006
    Location:
    Brookfield, CT
    Like in the pickup cavities, for example. Single coils?
     
  11. Modern Growl

    Modern Growl Supporting Member

    Joined:
    Jun 7, 2005
    Location:
    NY/NJ Metro Area

    Hey there - no, none of the above.

    All pots are connected with a common ground wire that ends at the jack (came pre-wired this way).

    All pots are making good contact with shielding as well.

    Bridge ground is connected to the jack ground. There is a wire connecting the jack ground directly to the shielding as well.

    No lugs or wires from any of the pots are touching ground.

    This is one of the cleanest jobs I've done... I'm stunned that I still have noise. Doesn't make sense....
     
  12. Means2nEnd

    Means2nEnd Supporting Member

    Joined:
    Jun 27, 2010
    Location:
    somewhere between York, and Lancaster PA
    I have done 4 preamp re wires in the last two weeks. 3 for a fellow TB’r and my new Streamer Stage 2 and every single bass I had to re-do something I always run into something new something different always an issue it is so frustrating but I always track it down 1 thing at a time.

    I had a ground issue before like that on the one I did there was a single strand hair wire touching the other tab at the jack I tried everything rewired all the pots and at the end it was the last and only thing. Now when I re=do the jack I put a small piece of heat shrink over each tab. There is a tech at BestBassGear I have called him a couple of times with similar issues. He suggested while the bass is plugged in with nuts off all the pots pull each pot out one at a time to find out one thing at a time. This helped me before. One time in the wires from the pickup I didn’t cut away enough of the shielding and when I soldered extending wire from the thin pickup wires I didn’t peel away enough of the foil and the foil was exposed and touching the hot wire. There is an “ah-ha!!” thing to track down I’m 100% sure.
     
  13. Modern Growl

    Modern Growl Supporting Member

    Joined:
    Jun 7, 2005
    Location:
    NY/NJ Metro Area
    ^ from the time I posted, I keep probing and probing.... everything looks as it should.

    No hot signal (hair) pot, wire, etc.. is touching anything ground.

    Ground is extremely secure on all pots and at the jack - and the jack is soldered directly to the shielding (in addition to making contact with it at the bolt.

    I just don't get it...
     
  14. Modern Growl

    Modern Growl Supporting Member

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    Location:
    NY/NJ Metro Area
    I have the bridge pickup ground connected to the jack ground (along with the bridge wire)....

    think grounding the pickup directly to the shielding (or a pot) would be a better spot?
     
  15. Means2nEnd

    Means2nEnd Supporting Member

    Joined:
    Jun 27, 2010
    Location:
    somewhere between York, and Lancaster PA
    One thing to try I had similar grounding issues before now I do the same thing by soldering a common ground to all the pots and then the ground from the preamp to the last pot then a single wire from there to the main ground on the jack seems to reduce grounding problem I don't solder the main ground to the shielding anymore try that. Or it could be a bad pot that isn't grounded correctly.
     
  16. Modern Growl

    Modern Growl Supporting Member

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    Thats exactly how it came pre-wired.
     
  17. Syco_bass

    Syco_bass

    Joined:
    Aug 13, 2008
    Location:
    Tucson, Arizona
    Disclosures:
    Custom builder - Arizona Bass Company/Curcio Custom Basses
    I would re-wire all of the grounding connections. Is this a "pre-wired" pre-amp from Nordy? I use them a lot and the first thing I do is remove the bare grounding wire and re-wire with sheilded wire. I also use a "star" ground and run everything to a common lug. I would also start with a clean slate. Remove everything from the cavity, clean it all up and scrap the sheilding foil (not needed). You don't have a sheild issue, IMHO you have a grounding issue. Cold solder joints might be an issue too. Once you remove the grounding wire that came with the pre-amp, and run new grounding wire to a comon lug, you should get better results. Good luck
     
  18. Modern Growl

    Modern Growl Supporting Member

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    I don't see how replacing the bare ground with a shielded ground is going to make any difference. The bare ground isn't touching anything it shouldn't.

    I went over every single connection from the preamp (pre-wired and the ones I made) - everything looks absolutley perfect.

    I'm not running a star ground... perhaps that is the issue?

    Could you walk me through the Star ground? Both pickups to it, right? Ground from all pots... anything else? Jack ground? Metal bridge ground?
     
  19. Syco_bass

    Syco_bass

    Joined:
    Aug 13, 2008
    Location:
    Tucson, Arizona
    Disclosures:
    Custom builder - Arizona Bass Company/Curcio Custom Basses
    Yes that is correct. Everything to one common lug. The bare wire thing doesnt seem like an issue, but it makes a difference. Good luck.
     
  20. Modern Growl

    Modern Growl Supporting Member

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    Jun 7, 2005
    Location:
    NY/NJ Metro Area
    I don't have an official guitar part to make a star ground. Anything you recommend? I see in my Sadowsky there is a metal prong with a circle everything goes to... anything metal like that?

    Or do you suggest something else? (trying to work with what I have an not place an order) - want to get this done tonight.
     
  21. bongomania

    bongomania Gold Supporting Member

    Joined:
    Oct 17, 2005
    Location:
    PDX, OR
    Disclosures:
    owner, OVNIFX and OVNILabs
    It doesn't require anything official--just a blob of solder, a piece of wire, the back of a pot. Any conductive metal tidbit that is not connected to the signal path.
     

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