Advice needed for shielding p bass

bat boy

I did up an old sunn made precision bass recently and I'm getting a terrible hum off it. Was wondering if anyone had any advice for shielding. Theres no shielding im either the cavity or on the back of the pickguard. Has anyone done a job like this before, any advice appreciated

Doctor J

It shouldn't really need it, the whole thing about P basses is the split pickup is a humbucker. You may have a faulty part, rather than an interference issue.

Dord

Doctor J wrote: »

It shouldn't really need it, the whole thing about P basses is the split pickup is a humbucker. You may have a faulty part, rather than an interference issue.

Well actually it's good to have it.

Even with a P-bass grounded properly it's still possible to get interference and noise. I shielded my fretless P with copper tape I bought from stewmac.com. Did the job great! watch your fingers though, it can cut you bad because it's really sharp. Alternatively you can use shielding paint.

My P-bass is super quiet now, even when my hands aren't touching the strings. :cool:

Here's a Jazz I shielded recently.

bat boy

Cheers for the reply doctor j. The hum is only audible when im not touching the strings or the bridge, as the bass is earthed when im touching it. Would this be the case if it is a fault somewhere?

Eoin Madsen

bat boy wrote: »

Cheers for the reply doctor j. The hum is only audible when im not touching the strings or the bridge, as the bass is earthed when im touching it. Would this be the case if it is a fault somewhere?

Yeah.

Is it a hum or a buzz? It's normally a buzz that comes and goes with the touching. There's a subtle but important difference!

bat boy

Joe Robot wrote: »

Well actually it's good to have it.

Even with a P-bass grounded properly it's still possible to get interference and noise. I shielded my fretless P with copper tape I bought from stewmac.com. Did the job great! watch your fingers though, it can cut you bad because it's really sharp. Alternatively you can use shielding paint.

My P-bass is super quiet now, even when my hands aren't touching the strings. :cool:

I was reading about copper foiling the cavity. Had a look in maplins y'day to see if I could get any but no luck. Do you know if its possible to pick it up in a shop or do ya have to order it? Also, what sort of paint would do the job? Cheers

bat boy

Eoin Madsen wrote: »

Yeah.

Is it a hum or a buzz? It's normally a buzz that comes and goes with the touching. There's a subtle but important difference!

Its a buzz I suppose.

Dord

bat boy wrote: »

I was reading about copper foiling the cavity. Had a look in maplins y'day to see if I could get any but no luck. Do you know if its possible to pick it up in a shop or do ya have to order it? Also, what sort of paint would do the job? Cheers

You might be able to find the shielding paint in a hardware or in Maplins. The copper tape can be bought from stewmac.com. The exchange rates are in our favour at the moment. Shipping is reasonable also.

http://www.stewmac.com/shop/Electronics,_pickups/Supplies:_Shielding/Conductive_Copper_Tape.html

I ordered the set of 3, at the bottom. It's enough to do several guitars or basses.

bat boy

Joe Robot wrote: »

You might be able to find the shielding paint in a hardware or in Maplins. The copper tape can be bought from stewmac.com. The exchange rates are in our favour at the moment. Shipping is reasonable also.

http://www.stewmac.com/shop/Electronics,_pickups/Supplies:_Shielding/Conductive_Copper_Tape.html

I ordered the set of 3, at the bottom. It's enough to do several guitars or basses.

Cheers for the link. Might put an order in. One more question, do ya have to use copper or can aluminium be used instead? Just asking as I know alot of pickguards come with aluminium taped to the underside.

Dord

You can use either.

bat boy

Just checked maplins website and they sell aluminium tape. Gonna take a spin out and get some. Thanks for all the advice guys. I'll let ye know how I get on.

Doctor J

bat boy wrote: »

Cheers for the reply doctor j. The hum is only audible when im not touching the strings or the bridge, as the bass is earthed when im touching it. Would this be the case if it is a fault somewhere?

It doesn't sound like an issue that shielding will have any effect on, tbh.

Voodu Child

Cavity shielding can be well worth the effort, but i'd agree with Doc that it's probably not the main issue in this case.

It just sounds like an earthing problem. Stray interference is hitting the bridge/strings, but isn't finding a great path to ground, so some of it is ending up travelling through your signal path and into the amp. When you touch the strings, it IS finding a good ground (your body) so is going that way instead, and the buzz goes away.

It could be the cable, the jack socket, internal wiring, amp, or even the actual ground connection in the wall socket. Im not saying these things aren't present, just not doing as good a job as they should. Its just a process of elimination to try and find where the bulk of the problem is, swapping guitars and cables and amps etc.

bat boy

Did the job. Made a huge difference. Can't believe it only cost me 3.50 for the aluminium tape.