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Old 11-22-2012, 04:40 PM   #1
Psy8cho
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Figuring out Noise Problem

Wasn't sure if I should post this thread in the Gear section or Gear build section.. so if anyone thinks I am at the wrong place, please let me know

Anyway I am facing a noise problem wich I can't seem to figure out..
At first my socket wasn't grounded, now it is but (almost) nothing changed.
I tried both of my guitars, Ibanez RG870QMZ and my Epiphone Les Paul special II on my Peavey Vypyr Tube 120W and tried different cables. But I keep having noise.

Let my try to describe the noise that I am having.
I always have a constant buzz, it increases when my hand nears the pickups and (almost) vanishes when I thouch something metal on my guitar. Still a little buz though, but bearable. So my first thought was grounding, fixed that part on the socket's end. Also tried two guitar's so unless both aren't grounded properly inside, something else is wrong.
I made some photo's of the insides of my main guitar, the Ibanez:

https://www.dropbox.com/s/sjug3g1gmr4grc7/IMAG0448.jpg

https://www.dropbox.com/s/a22h6yrddvp4ojc/IMAG0447.jpg

https://www.dropbox.com/s/ijyf26yu16n5qjy/IMAG0445.jpg

https://www.dropbox.com/s/21ev4grnp7rokn0/IMAG0446.jpg

As you can see the insides of the guitar are shielded, wich is weird considering the big buzz from the pickups.

But my biggest problem is that I am having trouble finding out what the 'actual' problem is. I am unsure of what to do in what order to test my signal chain and find the problem.

Hope you people can help me!

Edit:
I might have found a solution, let me try

Edit2:
The solution I thought I found was false, I had no sound at all.. interconnected something so no signal came through..
How can I check if my socket is really grounded?

Edit3:
You can tell I am trying to fix this :P
update, ground wire attached or deatached from bridge does not make a difference in noise. So I would say that's a definite ground problem right?
strange, if i touch it it almost disapears even without the ground wire attached. Also ground(attached to bridge) directly to extension socket's ground (empty socket) does not make a difference, does this mean my socket is not properly grounded?

Edit4:
Don't think it's the guitar ground is properly connected to the volume knob, which is good right?
Could it be the amp? How can I check this?

Last edited by Psy8cho : 11-22-2012 at 06:10 PM.
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Old 11-22-2012, 05:41 PM   #2
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What else is in the room. Flour lights, old style CRT TV, any other interference? Move the amp to another room and see what happens
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Old 11-22-2012, 06:13 PM   #3
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I tried this and I do notice a difference in hum if I put my guitar closer to the floor (it increases). But my noise completely disapears when I thouch something metal in the guitar and hold it high enough. but even when I don't hold it high enough, me touching it reduces the hum by 90% and moving my hand closer and from the pickups does not affect the noise much anymore.
How would you explain this phenomenon?

Edit:
if I connect a multimeter first to the ground of the socket and then either one of them, I get 0 or 230V which is correct right? so my socket is grounded?

Edit2:
Tried different amp, my SS Line 6 Spider IV 15W, still the same...
Could still be the guitar, how is the ground supposed to be connected?
Just can't find the problem...

Last edited by Psy8cho : 11-22-2012 at 08:00 PM.
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Old 11-23-2012, 12:10 AM   #4
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Quote:
Originally Posted by Psy8cho
I tried this and I do notice a difference in hum if I put my guitar closer to the floor (it increases). But my noise completely disapears when I thouch something metal in the guitar and hold it high enough. but even when I don't hold it high enough, me touching it reduces the hum by 90% and moving my hand closer and from the pickups does not affect the noise much anymore.
How would you explain this phenomenon?

Well, unsure. Is this a new problem or have you had this the whole time you've had the amp / guitar combo and only just now decided to write about it?

Edit:
if I connect a multimeter first to the ground of the socket and then either one of them, I get 0 or 230V which is correct right? so my socket is grounded?

I assume you mean the mains power socket? yes you should measure mains voltage between earth and active and close to zero between earth and neutral

Edit2:
Tried different amp, my SS Line 6 Spider IV 15W, still the same...
Could still be the guitar, how is the ground supposed to be connected?
Just can't find the problem...

If its still the same with a different amp, then it points to the guitar. Need to know is this a new problem or a long time problem you never solved.
..
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Old 11-23-2012, 02:06 AM   #5
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it has always been a problem. Decided to write about it because now I can actually test something because my socket is now grounded. Otherwise it would have been futile anyway
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Old 11-23-2012, 06:21 AM   #6
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Both of my guitars are schielded and seems that the ground is connected properly(https://www.dropbox.com/s/21ev4grnp7rokn0/IMAG0446.jpg), how can I test if they really are?

Last edited by Psy8cho : 11-23-2012 at 06:58 AM.
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Old 11-23-2012, 06:06 PM   #7
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Quote:
Originally Posted by Psy8cho
Both of my guitars are schielded and seems that the ground is connected properly(https://www.dropbox.com/s/21ev4grnp7rokn0/IMAG0446.jpg), how can I test if they really are?


Get a multimeter and set it to low ohms range.

From the output jack ground ring, test to all the pot bodies, the bridge, the pickup grounds, the switch grounds and also all points of the shields themselves in the cavities.

They should all read very very close to zero ohms. Test the ground continuity through your output jack and guitar cable also.
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Old 11-23-2012, 06:36 PM   #8
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Ok so I looked into that, most of it is zero or near zero. But when touching the shielding(faraday cage) and the ground it gives me huge resistance, this is normal?

Quote:
Originally Posted by Phoenix V
Test the ground continuity through your output jack and guitar cable also.


How can I test this part?
thnx for your responses btw!
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Old 11-24-2012, 12:21 AM   #9
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Quote:
Originally Posted by Psy8cho
Ok so I looked into that, most of it is zero or near zero. But when touching the shielding(faraday cage) and the ground it gives me huge resistance, this is normal?

If you mean the paint then possibly. If you mean the copper sheet under the controls then this sounds very odd. Any of pots and switches chassis mounts would also come into contact with the inner shield and so it too would be grounded also I'd think?

How can I test this part?

test the ground continuity from your output jack ground with the cable plugged into the guitar to the ground at the other end of the cable without it plugged into the amp

thnx for your responses btw!
..
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Last edited by Phoenix V : 11-24-2012 at 12:28 AM.
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Old 11-24-2012, 09:10 AM   #10
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Yes the paint gives a big resistance, the coppersheet gives around 0.3-0.6 on the 200 ohm setting.

Ok tested the continuity, from every where on my guitar, strings to the ground of the cable(base of the plug) it's around 0.3 or like from the tuning pegs it's a little more 1-3 ohms, touching the tip of the plug gives around 10-13 ohms everywhere.
Only part that didn't give result on the 200 ohms setting are the pods, but when touching the pots on the inside of the guitar it does gives 0.4 again.

This means my guitar is grounded properly?
how can I test the ground of my pickups?
Ground loop in my guitar maybe? How to test?
next test subject will be the amp? how to again? (Before I started this thread I never even opened the back of my guitar so i am sorry for the many noob questions)

Last edited by Psy8cho : 11-24-2012 at 09:12 AM.
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Old 11-24-2012, 09:23 AM   #11
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Quote:
Originally Posted by Psy8cho
Only part that didn't give result on the 200 ohms setting are the pods, but when touching the pots on the inside of the guitar it does gives 0.4 again.



Not sure what this means. Are you saying you get a high reading when you test from a pot chassis to the far end of the guitars cable ground ring with the cable plugged into the guitar?
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Old 11-24-2012, 09:30 AM   #12
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a little typo, "The only part....."
Yes like on the outside of the guitar, where you normally adjust volume or tone to the base of the plug of the guitar cable plugged into the guitar. and correction I didn't get a reading on the 200 setting but I checked I don't get a reading at all not even on 200K or 2000K
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Old 11-25-2012, 01:47 AM   #13
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Going out on a limb. Have you tried a different guitar cable?

If you dont have one, try wrapping your hand around the guitar cable itself. Does the noise increase?
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Old 11-25-2012, 05:49 AM   #14
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Yes I did and that one is supposed to be better quality even
But measured the Ohms for this one too and it's about the same 0.5 that kind.

Haven't tried wrapping my hand around it, cuz everyone is still sleaping here.

Other idea's?
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Old 11-25-2012, 06:21 PM   #15
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Well it still has to be something within the guitar, the cable or something within the house thats spitting out electrical noise. Light dimmers, flouro lighting, CRT TVs or monitors, etc.

As the amp is earthed (I'm assuming your using the 3 pin earthed plug with it), if the noise source was purely the amp, it would continue to buzz / hum even when you touched the bridge. Moving the amp around or to another room should notice a level of change in the noise.

Since you touch the bridge and it all goes quiet, or when you move the guitar around the hum/buzz gets better or worse theres something going on with the guitar or noise sources in the room or house getting into it. But even still a good shield should negate that somewhat.

If I had it in front of me I could go through it all and resolve whats going on, but if you're convinced there are no nearby noise sources (I can't check this) it just doesn't sound like your ground and shield is working as it should. Check to see there are shields within the pickup cavities.

You're just going to have to go through it systematically.
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Last edited by Phoenix V : 11-25-2012 at 06:23 PM.
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Old 11-25-2012, 07:10 PM   #16
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It is true that my room has more noise then the other room I tested it in, but that still bearable. But in both situations touching something metal reduced the main noise.
Also I found out that bringing the tone knob down, almost the whole way to about middle, reduces the noise significantly. Maybe that is of help?

I want to go through it systamaticly, I have been trying, but there are just so many things that keep popping up I didn't know existed. But I am learning a lot here
Also that other guitar of mine has the same problem, the noise goes away when I touch something metal.

Is there also a way to check if my pickups are grounded?
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Old 11-27-2012, 01:21 AM   #17
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You have a continuity meter, so asking how you know if something is grounded is kind of a moot point when you can just test the ground continuity on the spot. There's no need to guess.

Systematically test as in use a logical process of elimination through the whole circuit, starting from the very start.

IE: Desolder the final cable at your output jack. Record which way around they were soldered so you can reconnect them later. Then desolder your bridge pickup cable from inside the control cavity (again record how and where it was soldered so you can reconnect it later) and connect it directly to your output jack. If the cable is too short to reach then undo the output jack and move it to the cable, or buy an output jack and connect it. Get your guitar plug, plug it in and test for noise. If there is noise then make sure its not the amp itself by disconnecting the guitar plug from the amp. Else the pickup cabling is either rubbish, the cable shield has been damaged / broken, there is no shield in the pickup cable, too much shield has been stripped away exposing too much hot wire or there is no copper shield in the pickup cavities. Check for all possibilities.

If it is quiet, then the pickup and the cable is fine. Reconnect the pickup back to where it was. Then do the same with the neck pickup, etc, etc. After each successful test follow the cabling through the circuit to the next component and connect the next component direct to the output jack, replug and retest

As each component further down the line tests quiet after connecting it directly to the output jack, then reconnect that part back to how it was, then isolate to the next part and connect that to the output, etc, etc until you identify which component then introduces the noise.
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Last edited by Phoenix V : 11-27-2012 at 01:36 AM.
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Old 12-01-2012, 01:46 AM   #18
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Sounds like it isn't the guitar. You have another guitar that does the same thing. It would be very unlikely for both of them to be faulty.

It's not the cable, so you've narrowed it down.

It seems unlikely to be the amp, unless the internal earth connection is loose (not common).

If you are touching the bridge/strings, then you are effectively grounding them via your body, which will eliminate the spurious signals (buzzing).

Something easy to check:
Can you find the Earth peg for your house? Usually, it is a green wire coming out of the outside cladding, attached to a steel pin that is driven into the ground.. If the connection is loose here, you won't have the benefit of Earth grounding (passing any stray signal/noise to ground). This is also a safety issue.

I actually had a similar problem and it drove me mad for a while (not to mention the little annoying earth leakage tingles), until I tried a different outlet. The one I was using was wired up really weird - one black wire and 2 red!... I measured 150V differential between the earth on my tv and the earth on my lamp (other side of the room)!
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