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P Bass Shielding Issue


Pow_22
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My p bass has always has a slight shielding issue that ive just never got round to sorting.  Its just the usual mild hiss/hum that disappears when any of the metal components like the bridge or strings are touched.  However, the other day whilst finally replacing some old flatwounds I noticed somwthing weird.  When I touch any of the metal polepieces on the bass side pickup the hum went away just like when you touch the bridge or strings) but touching the treble side pole pieces actually amplified the noise!

 

Does this mean there is possibly something wrong with my pups (Alex Pribora handwound efforts) or just something that good shielding and checking the bridge/earth wire will sort?

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Is the earth wire soldered to the underside of the bridge, or is the wire just splayed out so that threads contact the bridge? I had a similar issue on a P which had the latter, and so I scraped back the bridge plate to reveal some copper, to which I could solder the earth wire: hum greatly reduced.

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I shielded my pbass with graphite spray and made sure all the wiring and soldering is okay, but touching the polepieces still generates funny noises (apart from that, shielding was a huge improvement). Also, the bass is still susceptible to the poor quality of electric wiring in the place I play.

So, I suppose it's normal.

Edited by shamrock198804
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Cheers for the replies.  Good to hear its not necessarily the pickup!  It could do with a good set up soon anyway so will book it in for a fettle and see if he's shield the cavity while its in too.  Might even treat it to one of them tonestyler tone pots :)

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The reason the hum/buzz reduces when you touch strings/metalwork is that you are grounding yourself via the bass/cable to the amplifier(etc) ground.

When you are near the bass but not grounded you become a source of electrical noise - generally mains frequencies and multiples thereof.

So the pole piece effect implies that some of the 'bass' side pole pieces are grounded whilst the 'treble' side pole pieces are not.

Test with a meter...

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