Metal Pickguards...noise issues?

[thebryman]

do metal pickguards cause hum problems? i have a bass that hums and makes noises when i touch the pickups...tried replacing the tone pot but that didnt change anything... checked all the grounding wires and that is all fine...

however i noticed when tapping the pickups and holding the metal pickguard with my hand at the same time... the noise isnt there...

any advice?

thanks in advance

brian

[gfxbss]

bry, i think you can find your answer in this thread. guitarnuts2.proboards45.com/index.cgi?board=repair&action=display&thread=1162292536

i also noticed that you posted a slightly similar questions a while back that if i remeber right ux began to help you with. did you try the quieting the beast mod? also, i noticed in the last post that you replaced the input. are you positive you wired this correctly? if you wired them backwards you could get some noise back.

Tyler

[avoriaz]

I think that when you are touching a grounded metal part of the guitar, your body is increasing the grounding effect and this quietens the hum.

I get the same phenomenon on my Aria strat. My room lights run off dimmers and they do create an irritating hum via the sc pickups. The hum reduces or disappears as soon as I touch the strings or any grounded part.

In fact I am considering making a grounding wire that I will wear around my wrist and connect to the bridge or other grounded metal part to reduce or even eliminate this hum.

I would welcome advice on this. My main concern is that I might be putting myself at risk of electric shock. If there is an electrical fault in the amp and the ground goes live with 230 volts (UK voltage), I can’t just drop the guitar as the wire will keep me connected and cooking.

I don’t want to die a rock and roll death just yet. ;D

[ChrisK]

I would welcome advice on this. My main concern is that I might be putting myself at risk of electric shock. If there is an electrical fault in the amp and the ground goes live with 230 volts (UK voltage), I can’t just drop the guitar as the wire will keep me connected and cooking.

I don’t want to die a rock and roll death just yet.

"connected and cooking"

Well, I wanted to be many things in life, but never a fuse......


"Drive carefully", the life that you save just might be your own...

[gfxbss]

i would most deff not put a ground wire around your wrist. read chris' sig. 230 is deff not low voltage.

[sumgai]

chrisk said:

.....
Well, I wanted to be many things in life, but never a fuse......

I was once informed that I have a short fuse.... does that qualify?

;D


sumgai

[JohnH]

I think that the reason touching the strings causes hum to be reduced is that then your body is acting as a shield behind the guitar. So a good foil-shielding job to the rear and sides of the cavity, touching either a foil layer on the back of the pickguard (or a metal pickguard), and all grounded, should do the same. There should be only one connection between the shield grounding and that for the signal ground, being a star-ground position.

John

[sumgai]

John,

If my body were a shield, then in theory, if I were to reverse the wiring on the output jack, and then touch the strings, I wouldn't increase the level of hum, would I?

Thought not.

It's been decided by researchers that our bodies are more or less giant re-radiators. That is, we are antennae, we pick up and re-broadcast (or more properly, we re-radiate) the AC field normally encountered in the environment. We merely concentrate it a bit, due to our size, and then let it go, so to speak.

When we touch a grounded part (and that needn't be something directly connected to the amp, it could be from another circuit run, so long as it is ground), we are indeed grounding our bodies, just as if we were discharging a build-up of static electricity. Same principle, different results. But we aren't acting as giant radiation blockers, that's QED by simply moving between a fluorescent light and your axe, then moving away. (Don't just turn your body while holding your guitar, that'll change the guitar's position within the AC field. Lay the guitar down, and while touching the strings, walk between it and the source of hum. Now walk away, still touching the strings. Your mileage shouldn't vary.

Or so say the pundits. At this point in time. Subject to revision, due to additional research. Of course. ;D


sumgai

[avoriaz]

Further to my post above about wearing a grounding wire, I actually got the idea from this site.

www.singlecoil.com/shop.html (second item)

It does look like a recipe for serious shocks if an amp develops a fault.

I think I will QTB my guitar or learn to live with the slight hum rather than die wearing a ground wire.

On a related point, is using a RCD (Residual Current Detector) on the amp power supply a good idea? I usually use them on irons, garden electric equipment etc but I do not have one on my amp mains plug.

I don’t know if RCDs are common in the US with your 110 volt supply. Here in England with 230 volts they are widely used. Many new build houses have them integrated in the consumer unit.

[sumgai]

avoriaz,

Further to my post above about wearing a grounding wire, I actually got the idea from this site.

www.singlecoil.com/shop.html (second item)

It does look like a recipe for serious shocks if an amp develops a fault.

I predict that the author of that article, the site's webmaster, the host provider, the ISP, and the whole WWW in general will all be sued into oblivion after the first death caused by advertising such insanity.

I think I will QTB my guitar or learn to live with the slight hum rather than die wearing a ground wire.

Good plan! ;D

On a related point, is using a RCD (Residual Current Detector) on the amp power supply a good idea? I usually use them on irons, garden electric equipment etc but I do not have one on my amp mains plug.

I don't know if RCDs are common in the US with your 110 volt supply. Here in England with 230 volts they are widely used. Many new build houses have them integrated in the consumer unit.

Oh, we have them too, but we call them GFCI - Ground Fault Current Interrupt. Same thing, different name.

We can buy them to install into existing outlet boxes (removing and tossing out the old outlet), and we can also buy extension cords with them built right in. That's handy! I've not seen any household appliances with such devices built in right from the factory, but I don't doubt that I will soon.

However you make it happen for your amp (presumably so that you can gig out with it, safely), do so. It's a small investment in a large item - your life!

Search past GN2 threads on the topic of safety. Go back at least 300 days, more if you've got some time.


sumgai

[avoriaz]

Thanks Sumgai.

I have a few little RCDs (GFCIs) that sit between plug and socket. You plug the RCD into the socket and the amplifier or other device into the RCD.

I will start using one for my amp from now on.

[sumgai]

avoriaz,

Thanks Sumgai.

I have a few little RCDs (GFCIs) that sit between plug and socket. You plug the RCD into the socket and the amplifier or other device into the RCD.

I will start using one for my amp from now on.

I foresee a long and prosperous membership here, due to your smarts. ;D


sumgai