Buzz, Me, the amp or the bass?

bandmaster188

So new fender rumble . I've done 2 rehearsals with it and no problems . Gigged with on Sunday and halfway through the 1st set I noticed quite a loud hiss/buzz. During the break I realised the tweeter was on so I switched it off and it all seemed fine even when turning the tweeter back on . Have been playing around with at home and I've noticed that there is a slight buzz up at gig volume which is more prominent with the tweeter on. With a stingray active pups the buzz is even greater still. And finally with my p bass, as soon as my thumb comes into contact with the plastic pickup cover the buzz increases significantly. What's occurring! Dodgy amp? Dodgy basses or dodgy bassist?
p.s have tried 3 different leads and different parts of the house.

Funkfingers

Skin contact with the rod magnet polepieces can induce a buzz. This is why they are often lacquered. For skin to plastic contact to cause noise suggests a conductive path across the plastic. Sweat would do.

Amateur attempts at screening single coil pickups can cause more noises than they reject.

Musicman Stingray pickups are not active - just the onboard equaliser circuitry. EMG replacement Stingray pickups are active. In either instance, the battery-powered pre-amplifier circuitry will generate a constant, low level hiss.

Signal compression will exaggerate background noises. 

Bridgehouse

Stop eating 9v batteries!

Have you tried a different lead? Edit - yes you have.

Could be you have a grounding issue with your electrics and it's not actually linked to the gig hum. Or the venue had a grounding issue as well.. (not uncommon)

ICBM

Possibly an earthing issue, although most of what you're describing is normal.

Does the P-Bass still make the buzz when you touch the pickup cover if you're also touching the strings (even with your other hand)?

bandmaster188

Not tried that icbm but did notice when thumb was on pickup cover and also touching the height screw, the buzz stopped. 

ICBM

bandmaster188 said:

Not tried that icbm but did notice when thumb was on pickup cover and also touching the height screw, the buzz stopped. 

That will happen if the height screw is grounded - it will be if the cavity has shielding paint in it.

Assuming it also stops when you touch the strings, it's either normal background noise or there's a bad earth where the amp is - you know the bass is grounded correctly to the amp. If it *doesn't* stop when you touch the strings, the bridge ground wire isn't making contact.