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P-Bass Hum

#42
steve_rolfeca said:
- The adhesive on adhesive-backed foil is non-conductive. Wherever separate pieces of foil overlap in a shielding job, you need to puddle some solder across the join.
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The copper foil sold by StewMac has conductive adhesive. it has flecks of copper in it.

I have some copper foil I bought on eBay that also has conductive adhesive.

But if the foil you have doesn't, then you need to solder it where it overlaps.
 
#44
Chef, just as a 'sanity check,' do this please: plug bass into amp. Do not plug amp into wall. Using your meter, set to 'continuity,' check between the ground lug of the amps' power cord and the strings on your bass. You should have solid continuity here. You can check your shielding, etc the same way. Everything should be tied to ground.
 
#47
Any news ?

I bought a Blacktop Jazz Bass one month ago and encountered this problem. I shielded the cavities with copper field, then installed an Audere preamp running in Low Z mode, then had an intuition that the grounding the poles might help, but in the end, it only reduced it.

When the palm of my hands is close to the pickups (without touching it), the noise is still audible, when I touch any metal part of the bass or remove my hands far from the pickups, the noise disappears. The other problem is the "clank" noise that occurs every time I put a finger on the strings or controls.
 
#49
bronislas - If you touch the strings/bridge/metal and the hum goes away it is a shielding issue, which is what chef had on the lakland.

If you touch the strings/bridge/metal and the hum gets louder you have a grounding issue.

Is the blacktop jazz a separate control and pickup cavity? If so, you will have to solder a ground wire from the foil in the pickup cavity to the control cavity. You shouldn't have to ground the pole pieces, that really only reduces the noise made when you physically touch the magnets.

Also, if the pickup covers can be removed from the pickups, ensure you shield the pickup covers without touching the copper foil to the solder leads.

Should solve your issue.
 
#52
Make sure you are shielding the pickguard as well as the body screw holes where the pickguard screws down. I put foil right over the holes so the screws actually pierces both pieces of copper foil to ensure the best contact.

Have some foil again go through the pickup cover screw holes so the screw acts as the connection to the copper shield lining the cavity.

And yea, I am not good with electronics I just hate buzzin basses, so I can shield them pretty darn good at this point.
 
#55
I've done just about everything mentioned above , except for shielding the pickup covers, and my Lakland still hums (not buzz)! It happens in most older buildings that have lesser quality wiring . . . our house is very new, and there is NO hum! I play at chruch too (an older building), and all my Fender and Lakland basses hum . . . I have just learned to roll volumes controls on/off between songs . . .
 
#57
but have you tried a different amp? Maybe you have a practice amp that you have laying around...or a friend that may let you borrow theirs, for testing purposes.
The only reason I say this, is because you mention that when you turn the lights off, the hum/noise goes away. You could be getting induction from the amp.
 
#58
monti2889 said:
but have you tried a different amp? Maybe you have a practice amp that you have laying around...or a friend that may let you borrow theirs, for testing purposes.
The only reason I say this, is because you mention that when you turn the lights off, the hum/noise goes away. You could be getting induction from the amp.
Click to expand...

No, that's a bass in need of shielding. I'm sure if the bass was unplugged from the amp the noise would go away. The the pickups that induce signal into the amp.
 
#59
dmusic148 said:
Yes. The new shielding will have little or no effect until you ground it all. Solder wires to each section and connect them all to ground(they don't have to all go to the same point if its not convenient to do so). And yes, doing what you suggested to the pickguard is wise.
Click to expand...

yes, if you want it to work you have to finish the job! That would be running a wire from the control cavity copper to the copper under the pickup. If you have copper with CONDUCTIVE glue, you can run a strip down pole pieces to ground them too. That strip must have a wire going to pickup cavity copper.

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Also put copper foil on pickguard under controls large enough so it makes a "lid" for the control cavity. Pots will ground it. But you need to run a wire from back of controls (or jack ground) to copper in control cavity. That makes it all sealed in a grounded copper box which should solve the shielding problem. Whenever hum goes away when you touch ground that is a sure sign that you have a shielding problems somewhere.

Hum in venues can be quite variable so what you "get away with" one night may not happen the next if your shielding isn't up to par.
 

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