P-bass hum?

[alanp]

Okay, so I've got this Squier Affinity P-bass. Bought it awhile ago, but my only amp (a little Marshall MG15CD) has been in Te Kuiti until yesterday. So, when it got back, I thought 'bugger the speaker' and hooked up the P-bass to it (since some way more professional bass dude ran HIS through Anvil's 20W Trainwreck and Fender 4x12 without it going boom.)

Whenever my fingers got close to the strings, the hummmmm went up! When they distanced themselves, the hum lessened, didn't go away totally though. And when I fiddled with what I presume was the tone knob, the only thing that happened was that it made the hum go away a bit more. This is with just a P-bass split pickup, no fancy PJ stuff.

Have I turned into a mutant, or should I check the wiring under the scratchplate? That was the first time I'd had that bass through any amplifier.

[ash]

What happens if you touch the bridge or the nut of the output socket? Does the hum go away or get worse?

It sounds like the bridge earth wire is either missing or connected incorrectly. There should be a wire going from under the bridge plate to the back of the volume pot (although it could go to the ground terminal of the socket or the back of the tone pot).