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Discussion in 'Pickups & Electronics [BG]' started by sublime0bass, Feb 27, 2008.

  1. sublime0bass


    Aug 2, 2007
    Boone, NC
    So I have a grounding issue.

    The setup:

    Squier P --> Peavey Tmax head -(line out)-> Crown xti 100 --> ampeg 1832he

    The facts:
    -The squier's insides were all solidered by myself. I did a good job in connecting it correctly and linking everything to string ground, BUT I have since put on a BAII, which I believe is electrically nonconductive. I also tried abrasing the bottom of the [black anodized] Badass to get a better electrical connection, to no avail. The body cavity is also completely unshielded. I am also open to the idea that I wired this incorrectly (although I used the Seymore Duncan instructions that came with my QPs).

    -So, if I'm touching the strings, there is massive hum. If I touch the pots, any part of my instrument cables, and either of the chassis of the amps, the hum disappears completely. This is not an issue when playing my relatively new EB0. Also, hum can be eliminated by rolling off the tone pot.

    -All devices involved are connected to the same power conditioner, so I don't think the hum is entirely local.

    Some stipulations:

    - The Tmax head (Which I am effectively using as a 60lb preamp) has 2 depression buttons near the line out: Ground lift and Pre/post EQ. If I do pre-eq, the buzz isn't evident but there is also almost no volume. If I do pre-eq, the volume is massive, but there is the hum (This is what I believe to be the "correct" volume level, based on the amp and cabinet's respective specs)

    -I've been thinking about the electrically isolating rackmount tabs. Good idea/bad idea/ no point with this application?
  2. joelb79


    Mar 22, 2006
    Lansing, Michigan
    Well for starters, the BAII is conductive. It sounds like you have a bad ground somewhere in the bass. It could also be the amplifier or the electrical in the house. I would double check your grounding first off especially to the jack and the pots.
  3. sublime0bass


    Aug 2, 2007
    Boone, NC
    This was not a problem with my old std bridge. It seems like the black powder coating wouldn't transmit the ground.
  4. Use a multimeter to check electrical connection
  5. lamxyz


    Mar 21, 2006
    Does the hum level changes when you

    A) touch the strings only and nothing else ?
    B) totally touch nothing at all ?

    If hum is louder when A and softer hum when B
    most probably its some wiring gone wrong

    If hum is louder when B and softer when A
    means got some grounding to strings
    but not as much as to the stuff in the control cavity.

    If hum is same in scenario A and B
    means prob no grounding to strings or
    that the cavity needs to be shielded better,
    try turning off all the room lights and move around

    If that helps.... means you should do more shielding

    btw, what kind of hum is this : )
  6. sublime0bass


    Aug 2, 2007
    Boone, NC
    its the kind that goes buuuZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ (ad naseum). ie the thread title

    from what i can tell the ground is the problem. as i said, when i touch the pots, the jacks on the instrument cable, or the cases of the amps the hum goes away (less so with the amps than the others)

    Ive tried to ground the strings, but its not really working. it is a black badass 2, though
  7. sublime0bass


    Aug 2, 2007
    Boone, NC
    going back to this same problem

    the ground is no longer a problem when i touch the chassis of my amps. I can touch the volume or tone knobs to eliminate hum. The ground is correct, HOWEVER, I am now sure the black badass 2 is not conductive, as i removed the ground from under the bridge, and then wrapped it around a string. upon touching the string, the noise is eliminated.

    I have already done some sanding to the back of the badass, do i need to do something to each of the saddles? im really really lost
  8. Try using a piece of that copper foil ( which BTW, I lined the full cavity of my mexi P with that stuff and did a star ground right into it, and its the quietest bass I own,and I;m a sound nazi!"), stuck down to the body right where teh ground wire comes on up. This will help keep the wire from imbedding in the finish. Use a small 1/2"-1/4" square is all.

    I got the copper foil from stew-mac.com for $17. I'm sure someone can mail you a small piece. Also, I put a beefy 22ga multistrand wire in the bridge ground, not the oem little thing. I also took a dremel to the spot where the wire ground to the bridge and cut the surface chrome plate off. Dont gouge it, be easy so as not to leave a depression.

    BTW, a standard VOM ( like my automotive ones), can't measure the mico ohm resistance of a a good ground.
  9. Matthew Bryson

    Matthew Bryson Guest

    Jul 30, 2001
    I've been through this. I had exactly this problem with a black BAII bridge.

    You are correct.

    I found that the bridge plate (once scratched) does have a good connection to the saddles and the saddles, once slotted, do have a good connection to the strings.

    The problem is with the bridge plate and the screws that they provide.

    I just posted this in another thread - I'll copy it for your convenience. This is a simple fix - I'm being detailed here - it's really not that hard.


    What we did to fix the problem was to scratch the coating off the bridge plate around one of the mounting holes on the bottom, and under the screw head on the top side. Then a ground wire that attached under the bridge plate was wrapped around the screw to keep it secure (we added an extra "jumper" so that I could take the pick guard off more easily in the future without being tied by short ground wire.) We found that the screw was also a poor conductor - we scratched the color off of the bottom of the screw head to correspond with the screw hole which now had exposed metal and we made sure to do the same along the threads where ground wire attached underneath the bridge plate. We found that once the ground wire made contact with the screw which made good contact with the bridge plate, the saddle already had a good contact with the bridge - so all was fine.

  10. Matthew Bryson

    Matthew Bryson Guest

    Jul 30, 2001
    LOL - I just realized that you ARE the other guy from the other thread.

    What is this star grounding you are talking about? Will that make your strings grounded?
  11. sceloporus


    Jan 3, 2008
    I have a similar problem, but in my case if I touch any metal component on my bass hum goes away. This hum only happens if a turn my treble knob up. It also only happens inside my house, Does mean it's a problem with my house's ground?
  12. Matthew Bryson

    Matthew Bryson Guest

    Jul 30, 2001

    If you touch any metal part of the bass it quiets the hum? Does this include the strings? If so, then I'd say everything is normal. If touching your strings does not quiet the hum, but touching other metal parts does (jack, volume knob, tone knob...) then I'd say your bridge / strings are not grounded and they need to be.
  13. sceloporus


    Jan 3, 2008
    Yes, touching the strings will quiet the hum But what I thought was so weird was that the problem only happens in my house.
  14. Matthew Bryson

    Matthew Bryson Guest

    Jul 30, 2001
    Then I think your ground is fine.

    Fluorescent lighting in your home by any chance? Radio station or Airport or anything that uses radio frequencies nearby?

    Single coil pick ups with no shielding in the cavity?

    It sounds like interference.

    You could probably fix it by shielding the cavity.
  15. sceloporus


    Jan 3, 2008
    Haha, there is actually a giant tower next to my house, I believe it is a cellular broadcasting station, but I'm not sure.
  16. crijan

    crijan Supporting Member

    Jul 6, 2005
    Dallas, Texas
    Endorsing: JH Audio IEMs
    I had the same problem as the original poster.

    Thanks to this thread, I sanded off some of the black coating from the Badass II Bridge where the ground wire would be touching and it fixed it right up.

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