My first guitar shielding

[omg81]

Heyo,

I've never done shielding before but I'm going to try it soon. I'll use my 20 yo. Epiphone SG G-400 which I also use for my wiring experiments, I'm not going to inflict my first attempts on my Gibson/Charvel/Jackson/etc.

I'm planning to apply copper tape (with conductive adhesive) to both control cavity and cavity cover, but I'm open to trying graphite paint for the cavity instead if there's a significant upside. I've heard copper tape provides more reliable shielding than graphite paint (unless you're applying many layers of paint), and this guitar's control cavity has very simple geometry so it shouldn't be that much of an effort. Also, I won't have to add a screw for proper earthing as they say it's easy to solder an earth wire to copper tape. I really appreciate your opinions if you think I'm wrong.

Questions:

A) Does it make a difference if I also shield the pickup cavities? I mean, on top they're open anyway so there's no full Faraday cage anyway. Also, the SD pickups (Black Winter) are shielded to start with if I'm not mistaken, I guess that's what the bare wire is for that I've soldered to earth. The secondary issue here would be the pickup wire tunnel in the guitar which is obviously unshielded as well, but I believe the SD wires are shielded and my amateur assumption would be that it doesn't make much of a difference if tunnel and pickup cavity are shielded if the pickup and its wires are shielded and soldered to earth. Please correct me if I'm wrong.

B) The control cavity already has a thin layer of graphite paint, sadly with some ~1cm² open spot. Can I just put copper tape on top of that or may there be some complication/would I have to remove the paint? (interestingly, my 10-yo. Gibson SG Special has no shielding whatsoever--it's just bare wood inside the cavity. Probably that's trademarked authentic Gibson shielding technology or something)

If you're wondering why, I want to get rid of hum on high gain that seems to be caused mostly by a badly shielded control cavity. Just putting my hand on the cavity cover produces noise. With the completely unshielded Gibson it's even worse, putting my hand on top between the pots causes noise too--the graphite-covered Epi doesn't do that at least.

Many thanks in advance!

 

[hamerfan]

Re: My first guitar shielding

Shielding an Humbucker guitar with already shielded pickup cables is not worth the effort imo. Are you experiencing any increased hum in your setup?

 

[Hollywood Rock]

Re: My first guitar shielding

When I work on my wiring with humbuckers and I have the shielded pickguard out and upside down and it buzzes then when I put it back in the shielded cavity and it doesn't buzz indicates that shielding helps.

 

[Chistopher]

Re: My first guitar shielding

Shielding is a great way to negate the noise created from shoddy wiring, but if the guitar doesn't make noise already, there's little use to it. It also won't stop the 60 cycle hum from single coils if you ever feel like shielding a Strat in the future.

But to answer your questions:

A) Shielding the pickup cavities doesn't make a noticeable difference unless you plan to split the pickups and they are uncovered. The cover on a humbucker does quite a bit of shielding anyway. If you do shield the cavities, make sure not to make a 100% closed loop or else you will risk treble loss. The long and short of it is that it is better to avoid shielding a humbucker cavity unless you can point to that as the source of the noise.

B) That small spot of unshielding wood is not going to cause any trouble. The main thing you should be worried about is a complete circuit. Touch the probes of a multimeter to varying spots of the conductive paint to make sure that there are no breaks in the circuit anywhere.

And one other thing, high gain hum is pretty tough to avoid even with a perfectly quiet guitar. Your cables, pedals, and amplifier will all add hum to your signal. That's just the nature of the beast and the reason why I always have a noise gate in my signal chain.

 

[Mincer]

Re: My first guitar shielding

If I already have the guitar open, I shield everything. There is no reason only to do one part if you are going to take the time to do it.

 

[omg81]

Re: My first guitar shielding

Thanks for your replies!

Yes, I do have noise issues with humbuckers, in all guitars. I'm no expert, but I think that's 60Hz/cycle/whatever hum, at least it sounds similar to what I found on Youtube when searching those terms. It is kinda tolerable but a little annoying. To give you an idea, I've got a Katana amp and in that PC control software I have to put the noise gate to 40-50% to silence it (edit: brown channel with gain halfway up), but that interferes with my playing/sustain so it's not an option.

When using coil split on a single HB it becomes extreme (both HBs coil split in middle position obviously reduces it again)... but since I very rarely use coil split (and never with high gain) this isn't really an issue.

I don't know, maybe it's because I live in a relatively old house in a city and there may be some nasty EMI source somewhere around here. In my previous flat I had a tram wire about 10m in front of the window and I could only play with the guitar at a roughly 90 degree angle to it because the noise was unacceptable. All with humbuckers. I noticed that it's kinda similar in this flat, there's a "sweet angle" where there's the least noise, and 90 degrees to that it's the loudest. The angle is always the same no matter where I go, so it's not caused by anything in the room and I guess it's somewhere in some distance to the house. Probably there are a thousand small sources but there also seems to be a big one in a certain direction.

So back to the guitar, as I said putting my hand on the cavity cover raises the noise level considerably. Putting my hand anywhere else on the guitar does nothing, and only very little if I hold it over the pups. So I'm pretty sure that's the main culprit that lets most of those stupid waves in.

So I will cover control cavity and cover plate in copper tape and leave the pickup cavities alone. I think I'll make a few recordings so I can do a before/after comparison. Again, thanks for your input.

 

[omg81]

Re: My first guitar shielding

Update:

I've covered the control cavity in copper tape (and slightly rewired according to some guidelines I found online) and it definitely makes a difference. Low frequency hum is still there but high frequency buzz is almost eliminated. I've made before/after recordings, I will shield the pickup cavities next and record again (although I suspect this will make less of a difference) and for comparison's sake I will also record those other (Gibson/Charvel) guitars. After all that I'll make a comparison video for anyone who's interested.

 

[OLDERBUDWISER]

Re: My first guitar shielding

Shielding an Humbucker guitar with already shielded pickup cables is not worth the effort imo. Are you experiencing any increased hum in your setup?

My ALT8 Epi tends to howl pretty easily?