Guitar shielding - thoughts on it?

[Alex]

Last week I had a bit of time on my hands for a small DIY-project, nothing major.

I've noticed that there is quite some noise (hiss/hum/modulation) in my amp when on high gain. After looking into this, it became clear that it's from my guitar and not from anywhere else.

I went the conductive paint route, painting the cavities I could reach on my LTD baritone and my Gibson Voodoo LesPaul. I painted them twice, thoroughly and grounded the body underneath each pickup and in the electronics cavity.

Here are my thoughts on this:
- shielding doesn't really do that much, there's still almost the same amount of noise on both guitars; oddly enough the neck pickups seem to have benefited more from it than the bridge units.
- my ESP already came with this type of shielding. In direct comparison the guitar seems a bit quieter, which I think is probably due to the covered pickups (the other guitars have open coil pickups).
- it seems to be universally recommended that the body is grounded. This doesn't seem to actually do anything as far as I can tell.
- touching metal parts with my hand, especially on the Gibson, is still is audible through the amp (a slight tap/click). The physical contact also slightly reduces noise/hum. Placing a cable between where I touched the guitar (for example the bridge) directly to the ground however doesn't reduce noise. Why is this?

I'm just wondering, shielding doesn't seem to do that much on a humbucker equipped guitar, or am I missing something here? I'm not disappointed, because there is a slight reduction in noise here and there (like I said the neck pickups seem to have benefited), but I had of course hoped for more.

[FELINEGUITARS]

I generally find hat shielding works well if done correctly
Coverage is important, and each separate painted area must have a contact screwed into it with a wire leading to the back of the pot  where the earthing takes place - or the big stud on the aluminium plate in a Gibson where the earth from the jack goes to.
Ungrounded earth screened areas will simply act as an antenna for noise.
Also put copper foil on the back of the plastic control cavity plate and make it so that it contacts the screening paint.
This completes the faraday cage around the electronics cavity and rejects outside RF

There are also a number of possible sources for noise getting into a signal chain but careful screening can help reduce those from within the guitar.

[Dave Sloven]

With the shielding on my SG Junior I just made sure that the pickup cavity and control cavity were connected with the paint.  I painted all the way through the connecting channel and tested it with the continuity tester.  I then screwed a wire into the wall of the control cavity, painted over that, and soldered the other end to the back of a pot.  I painted the back of the pickguard over the pickup cavity etc and the top of the guitar a little where it would contact. I also painted the lip of the control cavity where the cover sits, the back of the cover, and made sure that the screw holes were also painted.

My shield is pretty solid. It's difficult to eliminate 60 cycle hum from a Stockholm P-90 with a plastic cover but I think I've stopped most of the antenna activity.  I guess the next stage would be a nickel cover for the pickup.

I use a Boss NS-2 to eliminate the hum, which was feeding back to my high gain amp.  I still get the classic feedback if I stand too close to my amp on the wrong angle, but otherwise it is good.

My humbucker SGs have no shielding in them at present and I don't have any noise issues with them. If the noise goes away when you touch the bridge be sure to check the bridge ground wire.


I am also assuming that you have checked things like the power supply to your pedalboard, which can be a terrible source of noise

[Alex]

I generally find hat shielding works well if done correctly
Coverage is important, and each separate painted area must have a contact screwed into it with a wire leading to the back of the pot  where the earthing takes place - or the big stud on the aluminium plate in a Gibson where the earth from the jack goes to.
Ungrounded earth screened areas will simply act as an antenna for noise.
Also put copper foil on the back of the plastic control cavity plate and make it so that it contacts the screening paint.
This completes the faraday cage around the electronics cavity and rejects outside RF

There are also a number of possible sources for noise getting into a signal chain but careful screening can help reduce those from within the guitar.

I did all this, but on the Gibson it is difficult to reach all areas, as the canal for the three-way toggle is only partially accessible.
Does the cavity of the toggle switch also need shielding and grounding (I'm afraid I already know the answer to this question as I write it  ).

In any case, the LTD baritone is very straightforward in terms of cavity, I will have another look at the bridge pickup cavity and replace the grounding wire I installed - maybe I did the painting correct, but not the grounding?

[Alex]

With the shielding on my SG Junior I just made sure that the pickup cavity and control cavity were connected with the paint.  I painted all the way through the connecting channel and tested it with the continuity tester.  I then screwed a wire into the wall of the control cavity, painted over that, and soldered the other end to the back of a pot.  I painted the back of the pickguard over the pickup cavity etc and the top of the guitar a little where it would contact. I also painted the lip of the control cavity where the cover sits, the back of the cover, and made sure that the screw holes were also painted.

My shield is pretty solid. It's difficult to eliminate 60 cycle hum from a Stockholm P-90 with a plastic cover but I think I've stopped most of the antenna activity.  I guess the next stage would be a nickel cover for the pickup.

I use a Boss NS-2 to eliminate the hum, which was feeding back to my high gain amp.  I still get the classic feedback if I stand too close to my amp on the wrong angle, but otherwise it is good.

My humbucker SGs have no shielding in them at present and I don't have any noise issues with them. If the noise goes away when you touch the bridge be sure to check the bridge ground wire.


I am also assuming that you have checked things like the power supply to your pedalboard, which can be a terrible source of noise

It was my surprise that after elimination of all other possibilities, it clearly pointed to the guitars as the source of the noise. I had expected the cables from the effects or the PSU to be the cause, or the amp itself.

You don't hear a slight, microphonic "tap" through the amp if you touch a metal part on your guitar, especially on high gain?

[gwEm]

I must admit I was a shielding sceptic until this weekend when I noticed one of my strats had a good quality pickguard shielding plate fitted. I must admit, it is a quiet strat.

[Dave Sloven]

It was my surprise that after elimination of all other possibilities, it clearly pointed to the guitars as the source of the noise. I had expected the cables from the effects or the PSU to be the cause, or the amp itself.

You don't hear a slight, microphonic "tap" through the amp if you touch a metal part on your guitar, especially on high gain?

Not that I remember.  Unfortunately I haven't had a chance to check since your post.  I definitely get a big noise if I touch the lead to my own body at all, is that the kind of thing you mean?  I definitely don't get any such noise tapping metal parts of my guitar with the cable plugged in.

The bad bridge ground noise is just a hum that goes when you touch your finger on the bridge.  I have a similar noise in the active preamp of my Jazz bass at the moment, because its ground wire is not touching what it should.  That's a constant mmmmmmm sound.

You might also have a problem with your jack

With shielding I don't think shielding the selector switch cavity is necessary.  I know it can be a PITA on Les Pauls.  SGs are easy.

[Alex]

After checking things over and over again and doing various comparisons/experiments, I think the shielding is doing what it can and that there are simply some limits when it comes to high gain. However, I also think that some solder connection or pot/output jack is not ok on the Gibson. Unfortunately my soldering iron is not very good (lots of cursing today!) and I don't have any proper replacement parts for this guitar, so I will need to look into both of this at some later time.

I think now that this posts probably should have been in the Tech section instead. My apologies.

[Dave Sloven]

You might have a cold solder joint somewhere.

I usually use a 40W iron for this kind of work.  Just be careful not to leave it on the pots for too long.  25W is a bit low.

[pac90]

I know factory guitars come with conductive paint, but that aluminium duct tape is cheap, really easy to apply at home, and looks great