mic2002
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Post by mic2002 on Sept 3, 2009 8:44:47 GMT -5
I'm usure you guys have heard this before but I am getting the dreadful 'when I touch the metal parts the noise goes away' problem. On reading the Guitar Nutz advice this is due to the guitar working ok but the operator acting like a bucket of noise! I take it the solution is to isolate /shield the guitar? I'm using a gibson.On looking inside theres no shielding at all which was a surprise. I just want to check this is the right thing to do.Thanks.
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Post by newey on Sept 3, 2009 10:32:48 GMT -5
mic02-
Hello and welcome!
Usually, if the noise goes away when you touch the strings, it's a bridge grounding problem.
What model of Gibson is this, and of what vintage? And does it have HB pickups?
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mic2002
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Post by mic2002 on Sept 3, 2009 11:15:22 GMT -5
Hi the guitar is a 2008 Les Paul standard (not one of the new type) - has standard PAF pups.
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Post by newey on Sept 3, 2009 19:43:14 GMT -5
HB pickups such as PAFs should be pretty noise-free to begin with, and shielding is not likely to make too much of a difference. As I said, sounds more like a bridge ground problem.
You can easily test to see if this is the problem, without any destringing or disassembly (well, you do need to take a knob off).
Just get a piece of wire long enough to reach from the bridge to one of the controls. Strip about 3/4" of insulation off each end (if insulated- it doesn't need to be, any wire will do).
Wrap one end of the wire around one of the bridge posts and secure it temporarily with a piece of electrical tape. Remove one of the control knobs and wrap the other end around the pot shaft. Secure with a bit of tape. Plug in and play.
If this reduces the noise when you are not touching the strings/bridge/anything metal, then further exploration of the bridge ground is in order.
If the noise is the same, double check the connections on your temporary wire. If there's still no difference, then the problem likely lies elsewhere.
If you have a multimeter, you can also check the bridge ground for continuity between any part of the bridge and the shaft of the output jack. Using the meter is probably a surer method, but the wire method should tell the tale if you don't have a meter. Just make sure you have a good connection at both ends.
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Post by ashcatlt on Sept 3, 2009 23:55:49 GMT -5
Seriously, now. Am I just completely wrong about how the bridge ground thing works?
I asked in a fairly recent thread for confirmation/refutation, but got nothing. Maybe this time.
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Post by sumgai on Sept 4, 2009 2:09:55 GMT -5
ash, I don't recollect exactly what you're looking to have corroborated or denied, but I suspect that you're working up to shellacing newey for propounding the theory that touching the strings and thereby reducing the hum is somehow a bridge/strings 'grounding problem'. Or am i mis-reading your mind here? mic2002, Hi, and to the NutzHouse! What you've read so far is correct - touching the strings and then experiencing a reduction (or elimination) of hum is a sign of proper string grounding through the bridge. If any other metal parts also give you this result, so much the better, but then again, how often do you play by touching the (metal) pickup covers, or the screws, or whatever.... It's no accident that Gibson didn't shield that guitar - they don't make it a habit of "second-guessing" the ability of their humbucking pickups to buck hum. "It's supposed to work, so don't give the customer any reason to doubt it." Long story short, you can do the "Quieting the Beast" modification to your LP, just as if it were, say, a Tele (more than one cavity, etc.). Unless you are in an industrial zone with lots of power fluctuations, then this mod will probably take your humming and noise down to pretty near zero. No shielding job is ever perfect, but it's a sure bet that if you don't do this job, the noise won't go down all by itself...... We've covered in the past what you're requesting, so let me suggest that you use the Search function (above, the top-most menu on this page), and take a look around. Just be sure to use at least 700 or 800 days to go back - the default is only 7 days. HTH sumgai
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mic2002
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Post by mic2002 on Sept 4, 2009 3:46:01 GMT -5
Thanks, Sumgai! This makes sense to me. What is therefore happening is that the guitar is actually grounding me!. So what I need to do is shield the guitar from me and any extraneous noise. I'll do the search and come back when I've treid this.Thanks for all the replies.
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Post by newey on Sept 4, 2009 6:00:43 GMT -5
Will a shellacking hurt more than a Brazilian wax job? ;D
I had thought we had pretty well explicated this in the past, but apparently I'm wrong.
Beyond galvanic skin response, I have difficulty seeing the human body as a significant source of EM radiation. So what am I missing here?
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Post by JohnH on Sept 4, 2009 7:24:22 GMT -5
Do you have covered pickups? Usually a well wired LP is almost entirely shielded inherently, just by the use of braided wire for all th erunsand grounded pots. The only parts not shielded are the very tips of the wire at the joints and the caps.
On my '93 LP I have one covered and one non covered, and its all fine but the the uncovered one picks up a little more buzz than tho other
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Post by ashcatlt on Sept 4, 2009 11:25:18 GMT -5
SG - I didn't intend to shellac anybody, but you got my gist.
newey - does this hurt more than a waxing? (warning explicit lyrics)
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Post by sumgai on Sept 4, 2009 13:07:08 GMT -5
....... I had thought we had pretty well explicated this in the past, but apparently I'm wrong.
Beyond galvanic skin response, I have difficulty seeing the human body as a significant source of EM radiation. So what am I missing here? The human body is one hellaciously big antenna (in the scope of the guitarist's world) for all kinds of electromagnetic phenomena. The FNG has it correct, we are actually using the guitar's connection to the amp, thence to the real earth ground, to provide an easier path for all that radiation we've collected, and are now freely redistributing to anywhere and everywhere (notwithstanding the MafIAA's argument about making available.....). As in all things electrical, it's never as simple as we would like. That leads to some signficant portion of our instantiational generator-like capability leaking into our guitar's signal path, instead of going where we think it should. Thus we have "Quieting the Beast", and derivatives thereof. HTH upon further reflection..... JohnH is correct, the only time I've ever seen a Gibby hum more than about 5% of a stock SC-equipped guitar is when there's a big problem. That's usually either a connection that's gone south, or else an alleged "mastermind" that has failed to properly connect all the dots before buttoning it back up. Look for the obvious stuff first. Most often, it's not really all that subtle. And of course, the final word in trouble-shooting is to always test by substituting with Known Good Parts. This means that you test with another guitar that's known for a Gospel fact to have little to no hum in the same environment (location, amp, cable, etc.), or that you know the guitar doesn't hum under different circumstances (again: location, amp, cable, etc.) Only then should you play Mad Scientist (i.e., GuitarNut ;D)! HTH sumgai
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Post by newey on Sept 4, 2009 20:10:48 GMT -5
SG- Thanks for the explanation, that does make sense. Since this seems to be a topic we've gone around a bit on, your definitive explanation merits a +1 in my book! Thinking scientifically here ( Danger Will Robinson!), if our bodies act as antennas, and, if ungrounded via the strings/bridge, induce that noise through the pickups, then I would expect the resultant noise to be seriously reduced if the player in question were to remove his Keds and stand barefoot on a metal plate which was in some fashion earthed. No? NOTE: This is a "thought experiment". DO NOT try this at home, and especially not with that vintage 2-pronged Supro that's been in the back of your closet for 40 years. (And if you insist on trying this, use wireless) And Ash: I'll take a post-punk powerchord Shellacking over a Brazilian hot wax job any day . . . A hot Brazilian, now that's another story!
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Post by ashcatlt on Sept 4, 2009 21:22:17 GMT -5
I've been threatening to tie a wire around my bassist's (sanidar, one of our newest members here in the Nutzhouse) ankle and connecting that to some grounded point on our rack. He doesn't like that idea. I guess we'll just have to get around to actually shielding his axe. I'm afraid, newey, that when your wife finds out about the hot Brazillian, you'll be begging for the hot wax!
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Post by sumgai on Sept 5, 2009 3:07:47 GMT -5
newey,
Leaving aside the safety aspects of this 'theory', a person standing on a well grounded metal plate won't be any quieter, so far as the guitar is concerned. The main reason is that in order to stand barefooted on a metal plate, one's skin will be involved. That skin-to-metal contact patch will have anywhere from several hundred to hundreds of thousands of Ohms. I'm pointing out here that there will never be a "perfect" contact with ground that will force all collected EMI to be dumped down the "easiest path" of our hypothetical metal plate. Translated, that means that our bodies will always have enough EMI "left over" to radiate into the guitar's signal path, all other noise-reduction schema notwithstanding.
This goes to explain why, when we touch the strings, we get some (or perhaps a lot of) noise reduction, but not nearly a perfect kill of all noises - it's the skin resistance, compounded along with the resistance of the rest of the path heading towards 'earth' (real ground).
Not to mention that our bodies are not the only source of noise detected by our pickups. If you put down your noisy guitar and walk away, you'll note some reduction in noise, just from being further away - but you'll still hear something, the noise won't all disappear. Sad, that.
Fortunately, we can "head 'em off at the pass" with a Faraday cage! ;D
HTH
sumgai
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Post by sydsbluesky on Sept 5, 2009 11:48:34 GMT -5
Not a terrible idea for a recording studio.
Metal roof, metal siding and metal screens in every window + Some hours of tedious soldering + A big metal rod and a sledge hammer =
The perfect house for jamming?
Either that, or that old axiom about living under power lines might solve your problem. Then again, you could probably slow the electric meter down a little with an inductance coil...
Either way, eating the lead paint chips is still a bad idea.
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mic2002
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Post by mic2002 on Sept 7, 2009 4:06:40 GMT -5
Well I thought I would let you know that my fairly basic attempt at shielding has WORKED!! . This model of Gibson was the last of the 2008 older style - ie not the new edition 2008. What I did was used aluminium foil in the control and switch cavities and then gave a brush of conductive silver paint to bridge the tape joins. Then added the same to the covers. A big reduction in noise. Still have a little bit of noise as before but nowhere near as bad. I replaced the stock (covered) pickups at the same time with Bare Knuckle Mules (uncovered).Wow! It is worth noting that this model of gibson has a metal plate that the pots are mounted onto which may not have helped with the original problem - but ended up being a useful central gounding point since it sat right onto the new shielding so acting like a star ground for everything. Anyhow it worked for me. Thanks for all the replies.
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Post by ashcatlt on Sept 7, 2009 9:51:54 GMT -5
Glad to hear you're happy with it now.
Of course, we have no idea if it was the shielding or the new pickups. It's also possible that in re-wiring you managed to fix (replace) a cold solder joint somewhere.
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