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Shielding Issue?

mattattack187

mattattack187

Bass Enthusiast
Supporting Member
Feb 2, 2012
2,470
2,434
Ellsworth, ME
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#1
Had my luthier shield my Jazz Bass before he installed some new Area J pickups. I get home and the Bass is pretty noiseless when I'm not playing and the fingers off the strings. As I move the bass around, there's a crackling noise. Any time the bass is shook, or moved, there's a crackling. I loosened a screw just a tad on the control plate and although there's a small amount of noise when my fingers aren't touching the strings (kind of what I was used to before the pickup swap) the crackling stops. Tighten the screw again, back to the crackling.

My luthier shields with aluminum and he overlapped it around the edge of the route of the control plate, but did not tape the control plate.

Any ideas what could be causing the crackling?
 
#2
My guess is something is touching the shielding that shouldn't be. Like the input jack. If this is the culprit, it may need to be loosened and rotated so the contacts are away from the sides of the cavity. Or you could try covering the area around the jack with electrical tape.
 
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#3
Try taking one of those no static fabric sheets they use for laundry and wipe off the plastic pickguard. I have seen static build up in the plastic. Just one idea.

Edit: I misread the original post and, of course, this isn't the problem you have at all.
 
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#5
If the control plate is metal, it shouldn't need to be shielded. However, if there is paint or some other kind of coating on it, it might not be making good contact with the shielding of the control cavity. It might help to lightly sand the underside of the control plate where it contacts the shielding. (Of course, if the control plate is plastic or wood, then it needs to be taped on the underside.

My $.02 -- the shielding should be extended and bent over all the way around the cavity, so it touches the control plate all the way around. Also, there should be tabs extended over the screw-holes, so that the screws not only hold the control plate to the body, but also help create a solid electrical connection between the control plate and the shielding.

More $.02 -- I prefer to use copper for shielding. From what I understand, it's a better conductor than aluminum, and it's easier to solder. And it's not that expensive if you look for it on ebay.
 
#6
The way he shielded it was he taped the bottom of my Pickguard and had a tab extending from the pickup cavity to touch the pickguard. Control cavity all shielded, control plate makes contact. No soldering of a separate ground wire as I commonly see done around here.

The unshielded noise isn't bad by any means, just enough for me to ocd over. I practice through studio monitor headphones so I'm not even sure how it sounds through an amp/cab.
 
#7
Your shielding job is incomplete, take it back to the tech and have him complete it. If you paid for a complete job you should not be the one troubleshooting it. I would imagine he did not properly ground the shielding, particularly since you say there is no added ground wire. Did he shield the pickups as well as the individual routes?

On a side note, I wouldn't recommend a tech who uses aluminum, but that is just me. It does just as well reducing noise but it is very hard to solder to and it cannot be obtained with conductive adhesive, at least to my knowledge. I have used it with success many times but I would never do it again.
 
#9
mattattack187 said:
The cavities are shielded yes. I just electrical taped the tab/pickguard connection to defeat it for now until I have him look at it again. Luckily he works on his own and doesn't charge up the ace like music stores do.
Click to expand...

Are the pickups shielded? Some complain about the effects on tone but most basses I work on do not get silent without shielding the pickups. I have never noticed a change in tone personally.
 
#11
I gave up thinking about it. He's gonna fix it no charge next time I head over. Hate to tell a guy how to do his Job but maybe I should refer him to the Shielding Tutorial thread on this site lol....He does great work though and is a great guy, figured he wouldn't have an issue taking another look at it.
 
#12
Just to follow up, I noticed the shield would kick on/off by pressing the pickguard by the aluminum tab from the neck pickup. I scotch taped down a strip of aluminum foil to the tab and then to the foil on the pickguard and now everything seems to be fine....I tried something similar the other day by just folding up a piece of aluminum and putting it over that tab. I'm guessing the connection just wasn't holding between that and the guard too well?

it wasn't the most technical fix but it works....
 
#13
That's exactly why I don't like tabs. IMO the only tabs in a shielding job should be to extend the shielding out to the plate/pickguard screw holes. Other than that, the shielding should extend about 1/8" beyond the edge of the shielded cavity all the way around it. It's much more secure both in terms of the shielding doing its job well and the electrical connection between the shielding in the cavity and the shielding on the plate/pickguard.
 
#14
BlueTalon said:
That's exactly why I don't like tabs. IMO the only tabs in a shielding job should be to extend the shielding out to the plate/pickguard screw holes. Other than that, the shielding should extend about 1/8" beyond the edge of the shielded cavity all the way around it. It's much more secure both in terms of the shielding doing its job well and the electrical connection between the shielding in the cavity and the shielding on the plate/pickguard.
Click to expand...

I'm starting to see what you mean! I can't find any aluminum foil tape with conductive adhesive in my area, I'm most likely taking it back to him this weekend but at least the main issue has been pin pointed.
 
#15
I don't know if you think you might be anticipating more shielding jobs in your future, but it might be worth your while to get some copper shielding tape with conductive adhesive. In this particular situation, assuming the aluminum shielding in the cavity is good, you could just put the finishing touches on the bass yourself.

For future reference, using copper tape, I'm quite sure you could do at least as good of a job at shielding as your tech can do (better, actually, on the basis of this experience) if you simply are careful and take your time. You can get a roll of copper tape that's 1/2" x 55 yards (165 feet) for under $20 on ebay, and from a source located in the States if that's important to you.
 
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#16
BlueTalon said:
I don't know if you think you might be anticipating more shielding jobs in your future, but it might be worth your while to get some copper shielding tape with conductive adhesive. In this particular situation, assuming the aluminum shielding in the cavity is good, you could just put the finishing touches on the bass yourself.

For future reference, using copper tape, I'm quite sure you could do at least as good of a job at shielding as your tech can do (better, actually, on the basis of this experience) if you simply are careful and take your time. You can get a roll of copper tape that's 1/2" x 55 yards (165 feet) for under $20 on ebay, and from a source located in the States if that's important to you.
Click to expand...

Appreciate the reference. This is a Bass I've pieced together and I got the Dimarzio's for a very good used price. I was looking into the EMG J Set before I jumped on the Dimarzio's. The EMG's would obviously be the end all to the ground noise I wasn't too fond of before the shielding.
 
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#17
mattattack187 said:
The EMG's would obviously be the end all to the ground noise
Click to expand...
I don't know about this. I know active basses have no problems with line capacitance, and certain pickup/control arrangements that are problematic with passive basses, but I have seen a lot of active basses with shielding. That leads me to believe proper grounding is as important, possibly even more important, on active basses as it is on passive basses -- but I don't have experience with active basses, so this is speculation on my part.
 
#19
Just to give you a reference, here is a shielding job I did on my bass a while back. (It's the 3-pickup jazz in my avatar.)

BrozTone_zps5a35d94c.jpg


I used a few layers of tape. I used a tool to get the tape tight into the corners -- anything will work, like a popcycle stick or a spoon handle. I used copper tubing for the wire channels, then I taped and soldered the ends to both the control cavity and the pickup routes. I soldered the bridge ground to the shielding, and then covered it with more tape for a super clean look. My tech was highly impressed with it & called it bulletproof. I'm not a professional, I just took my time and was careful.
 
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#20

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