Shielding a P90-loaded Gibson?

imalrightjack

After discovering that the source of all ills with my 'noisy' instruments and amps is actually the house I live in (long story, posted elsewhere with no conclusion!), I've today found that my Gibson Midtown (loaded with humbucker-sized Bareknuckle Mississippi Queen P90s) is pretty much silent at one specific angle.  This made me wonder whether some shielding might help tame the noise and, if so, the best steps to take.

Copper taping the cavities?

Xsmnmy

The idea would be to enclose the whole pot cavity, with no gaps and foil on the back of the cover too, so the whole lot is insulated. Could be quite awkward but should work. You could use conductive paint also.

imalrightjack

Are all foils pretty much as good or are there brands to look out for? And what about the pickup cavities?

Out of interest, I took the guitar outside and over the road with my Blackstar Fly and there's definitely one distinct angle where the interference clears up. Lots of overhead powerlines

merlin

Making a Faraday cage around all the electrics requires a bit of work but really helps. 
I used conductive paint on my Gordon Smith with P90s. I took off all the electrics and applied three coats of shielding paint, including all the wiring routes. I allowed each coat to dry for 24 hours, just to be sure and it really helped. I don't think you're ever going to make a P90 totally hum-free, but the pickups I have installed are Fralins and after the painting, the improvement was amazing. It's now totally manageable. 

I'm not sure how one would do it on a semi-hollow but I'm sure it's doable. Check out youtube for tips. 

equalsql

My 79 LP Pro Deluxe has p90s and all the electronics are contained in a metal tin whose shape matches that of the cavity. It must work as I not noticed any major issues with noise when playing it.

ICBM

imalrightjack said:

After discovering that the source of all ills with my 'noisy' instruments and amps is actually the house I live in (long story, posted elsewhere with no conclusion!), I've today found that my Gibson Midtown (loaded with humbucker-sized Bareknuckle Mississippi Queen P90s) is pretty much silent at one specific angle.  This made me wonder whether some shielding might help tame the noise and, if so, the best steps to take.

No. That's electromagnetic noise - shielding only stops electrostatic noise. Single coils will always pick that up unless you enclose the whole pickup in a ferromagnetic casing - which would stop the pickup working. (There is a very specific non-ferrous magnetic shielding alloy called 'mu-metal' too, but that would have the same effect.)

The clue is that it goes away at a specific orientation. If it's universal no matter how you orient the guitar, it's electrostatic noise or ground loop hum, in which case shielding and/or star grounding will help.

The solution to electromagnetic noise is humbuckers...

imalrightjack

Ah! @ICBM That's fine. I can live with it. I don't really understand it but can now read up on it! My humbuckers are all fine, so that's reassuring. 

Jack_

Copper shield all the walls in your house, turn it into a faraday cottage.

imalrightjack

http://www.ehx.com/products/hum-debugger

Worth considering?

ICBM

imalrightjack said:

Ah! @ICBM That's fine. I can live with it. I don't really understand it but can now read up on it! My humbuckers are all fine, so that's reassuring. 

The real problem is when you have to play a gig with a single-coil guitar and the stage is so electromagnetically noisy that the only way to not have an overpowering hum/buzz is to stand and hold the guitar very still at a specific - usually awkward, and stupid-looking - angle to the stage.

That's why any guitar I intend to gig with has at least RWRP single coils, if not full humbuckers - so at worst, the two-pickup sound is hum cancelling. Just occasionally you need it, even if it's not necessarily the sound you would want to use.

NelsonP

ICBM said: 
The solution to electromagnetic noise is humbuckers...

I have a tele deluxe with humbuckers and it makes a lot of noise until you touch the strings, or bridge. Then it's quieter.
Would shielding help with that?

ICBM

NelsonP said:

I have a tele deluxe with humbuckers and it makes a lot of noise until you touch the strings, or bridge. Then it's quieter.
Would shielding help with that?

Yes. If I remember rightly those are a bit of a rat's nest inside, and in particular the wiring from the jack to the switch is not shielded at all! If so, simply replacing that with a proper shielded cable will probably make a big difference. If that doesn't do enough, you'll need to fully shield the control cavity and switch cavity - I would use copper tape, I find it much more effective than shielding paint. Tidying up the excess wire length may help too, even of the shielded pickup cables.

NelsonP

Brilliant. Thank you.

Well not exactly brilliant, but you know what I mean.....