Fender P Bass grounding problem - help please

[Bassguy1]

I've got a 98 Fender MIM P bass. I replaced the stock pickup with a new Fender 62 reissue split coil and the bridge with a hipshot B style. Butch Ammons over at Bayou Audio crafted a new P bass harness for me with pre soldered pots and jack. I've now got a grounding hum that I can't get rid of (except when I touch anything metal on the bass when plugged in). I've checked the bridge ground wire as well as the connections to the pots and all seems well. Does anyone have any suggestions as to what it could be? I've tried using a different guitar cord but no luck.

 

[phall2112]

Having the same problem on a jazz. After all my research, im leaning to a shielding issue.

 

[Rocky McDougall]

You might get a schematic of your type of setup and see if something is miswired. If the instrument is making noise now, in the same environment (room) with the same amp and cable as before, I would think it is not wired correctly. Normally this sounds like a bridge grounding problem. Have you tried a seperate jumper wire to the bridge? Or, if you have a multimeter, check the continuity. Shielding the cavities is always a good thing to do but this was not your problem before rewiring.

 

[Bassguy1]

You might get a schematic of your type of setup and see if something is miswired. If the instrument is making noise now, in the same environment (room) with the same amp and cable as before, I would think it is not wired correctly. Normally this sounds like a bridge grounding problem. Have you tried a seperate jumper wire to the bridge? Or, if you have a multimeter, check the continuity. Shielding the cavities is always a good thing to do but this was not your problem before rewiring.

Good suggestion...I'll try a separate jumper wire to the bridge. Cavities are shielded with copper tape already.

 

[Son of Magni]

If touching the strings makes the hum go away that only proves the bridge IS grounded properly.

You have some other problem, like maybe the case of one of the pots is not grounded.

 

[Bassguy1]

If touching the strings makes the hum go away that only proves the bridge IS grounded properly.

You have some other problem, like maybe the case of one of the pots is not grounded.

Interesting...I never knew that about the strings. What should the two pots (V/T) be grounded to? Do you know where I can get a passive P bass schematic to make sure they are wired correctly?

 

[SubSectorSucker]

One of the most common misconceptions going around the internet (if you touch the strings and the hum stops, its a grounding issue). It's the exact opposite. If you touch the strings and the hum gets louder, THEN its a grounding issue! You have a shielding problem, my friend! Here is a great article that will explain what is going on with your bass.....I hope more people find it


http://www.guitarnuts.com/technical/noisebucket.php

 

[Bassguy1]

One of the most common misconceptions going around the internet (if you touch the strings and the hum stops, its a grounding issue). It's the exact opposite. If you touch the strings and the hum gets louder, THEN its a grounding issue! You have a shielding problem, my friend! Here is a great article that will explain what is going on with your bass.....I hope more people find it


http://www.guitarnuts.com/technical/noisebucket.php

Very interesting article. Thanks so much for your reply.

 

[Bassguy1]

One of the most common misconceptions going around the internet (if you touch the strings and the hum stops, its a grounding issue). It's the exact opposite. If you touch the strings and the hum gets louder, THEN its a grounding issue! You have a shielding problem, my friend! Here is a great article that will explain what is going on with your bass.....I hope more people find it


http://www.guitarnuts.com/technical/noisebucket.php

SubSectorSucker was right on. It was a shielding problem and not grounding. The control and pickup cavities were already shielded with copper tape so I went a few steps further. I extended the shielding tape in both cavaties so it folded over the cavity edges and onto the body by about 1 inch where possible. I then placed more shielding tape across most of the back of the pickguard making sure that each row of tape overlapped the one next to it by about 1/4 of an inch. I then placed a small drop of solder right on each tape seam so the entire back of the pickguard was "connected". When I installed the pickguard the foil tape on the back of the pickguard and control cavities are touching and are now one single "connection". I also placed some tape under the bridge, sticky side on the wood and made sure the bridge ground wire was resting on the foil before attaching the bridge. The bass is now as quiet as a mouse at all playing volumes whether I touch the strings/metal parts or not.

 

[SubSectorSucker]

Awesome! Glad it worked for you! Oh, and in the event of an alien invasion, I think Im going to hide inside the body of your bass!

 

[jeffbrown]

I've been trying to track down hum in my system, and discovered that one of my basses wasn't properly grounded at the bridge. Still, I have what I think is a 60 cycle hum from my amp (Fender M80 combo w/another Fender 1x12 cab) with my other two. I think my *house* isn't properly grounded.... I'm not an electrician, nor do I play one on TV; how do I find out if the circuits in my practice room are grounded?

 

[kev bass]

Interesting...I never knew that about the strings. What should the two pots (V/T) be grounded to? Do you know where I can get a passive P bass schematic to make sure they are wired correctly?

they should be grounded to them selves, and to be safe run a ground wire back to the bridge ground, that will guarantee a solid circuit

 

[kev bass]

I've been trying to track down hum in my system, and discovered that one of my basses wasn't properly grounded at the bridge. Still, I have what I think is a 60 cycle hum from my amp (Fender M80 combo w/another Fender 1x12 cab) with my other two. I think my *house* isn't properly grounded.... I'm not an electrician, nor do I play one on TV; how do I find out if the circuits in my practice room are grounded?

when your cell phone rings do you hear it in the speaker?
that might mean you have a problem in your house. also pbass are gonna hum. all non-humbucking pickups will. i reccomend running your power through a power conditioner at the front of your chain. that might help. alo i have had bad house power blow up my amp. power conditioners are great safety tools.

 

[Beej]

when your cell phone rings do you hear it in the speaker?
that might mean you have a problem in your house. also pbass are gonna hum. all non-humbucking pickups will. i reccomend running your power through a power conditioner at the front of your chain. that might help. alo i have had bad house power blow up my amp. power conditioners are great safety tools.

You know this is an old thread, right?

Cell phone? Seriously?

P-bass pickups are humbucking, that was their point in the first place many moons ago.

Power conditioners are glorified and expensive powerbars...

 

[jonno1707]

subscribed

 

[oddestfellow]

I just registered for this site to ask this very same question. I have a '96 MIM P-Bass Special with stock P/J setup that's having the same issue. I had an aftermarket neck (beautifully made by USA Custom Guitars) and a Badass bridge installed at the same time, so I thought it might be a bridge ground issue, but I'm thinking it's probably a shielding issue. If I'm facing the amp I get the buzz. If I turn away from the amp (I guess essentially "shielding" it) it goes away. Guess it's off to the store for some copper shielding tape!