Help- Gtar Hum is just to bad!!!!

[JohnGardner]

Guys,
I have a really bad hum coming from any electric Gtar connected to my mixer.
I have tried two Gtars, two cables, micing an amp and direct into my mic pres and it's still there.
I turned off everything in my studio except the desk, the active monitors and plugged a Gtar straight into the HiZ input on the DAW. No better, it's still there.
I am not sure if its a grounding problem of some kind? I notice that it's not only the desk. If I plug direct into an amp the noise happens from the amp as well so it seems to be from the GTAR or cable.
Is there anything I can do to stop this. I have no flouresant lights, no dimmers but the power comes through the house first I think before it makes it's way out bto my detached studio.
My system is really quiet except when a electric gtar is plugged in to anything. Then it sucks.
I see my desk has a grounding terminal on the back but what do I connect this to in a wooden room and what kind of wire do I use?. I am not convinced it's the desk anyway.
It's a big problem as Gtars at the moment are un-recordable with the hum.
Can anyone let me know the steps to tracking down and fixing the hum like this. It's alot better when the strings or the gtar plug is touched but still really bad.
Thanks and help!!!
JohnG

[Sideshow]

just had a quick read - you got a beauty here huh!?

I put gtrdad onto this the other day - might be some ideas in here..

http://www.analog.com/UploadedFiles/App ... AN_347.pdf

Also this

http://www.evor.com/askrick_54.html

Take Care

[Aaronw]

John,

Is your computer monitor for your DAW a CRT?

What is your grounding for all the electric, and electronics?

What kind of desk or console are you using that has a grounding lug?

[guitardad72]

Is your computer monitor for your DAW a CRT?

IF the monitor is the source of the problem then turning the guitar to a different angle to monitor OR by backing away from monitor the noise should decrease until it's almost gone. A PITA to work that way, but this is my experience with monitor noise in a guitar.

Another way obvioius to decrease most noise in a guitar (eliminate sometimes) is to use a double coil PU guitar or with a Strat style use PU position 2 or 4 so that 2 PU's are on, out of phase. But that all depends on if the guitar is wired modern (80's and on, middle PU is reverse polarity) or older (pre 80's middle PU same polarity as other PU's) OR if someone decided to go there own route and reverse either just neck or bridge PU... and still this a PITA if you just want a single coil bright quaky sound.

Plugged in acoustics with piezo PU can also have this problem.

It's a lot better when the strings or the gtar plug is touched but still really bad.

The guitar is "looking" for a ground. Another method, until you find actual source of problem, you can try this:

1. Make sure your hand is on string or metal part of guitar.
2. Take your shoes and socks off.
3. Find something metal attached to your gear near the floor, I've used the bottom rail of a rack, I think I also used something that was not attached to gear but can't remember.
4. Plant your bare foot on the metal.

This has worked for me at least 5 times or more in my life recording guitars in not the best of situations. I can't remember it not working, except in situations where computer monitor, or lights are the cause.

I do wonder if it's possible to get shocked trying the above?

Also note a cheap guitar in some situations will be noisy where a more expensive well built guitar will be almost noiseless. I love Fender guitars with the "noiseless" PU's.

Sorry I can't tell you how to find the actual problem.

Marc

[JohnGardner]

Guys,

I think that I tracked most of the problem down to a cheap wall adaptor that the gtar amp was plugged into. The power cable was a US two pronged version and we had one of those airport adaptors on the end of it to convert to our three prong triangle plugs.

I unplugged everything in the studio except for the amp and the hum was still there so it was not the computer or any other gear in the control room that I could hear.

I think that the house aircon and dishwasher/washing machine are not helping the cause as well but I need to do some more tests. In short if they bare the problem I can turn the aircon off on the main switch board in the house and tell the misuss to stop cleaning when I am tracking!!.

A hollow body electric probally does not help as well.

I will keep you posted.

JohnG

[John Sayers]

JohnG - sounds like the guitar's problem. I've always had a sheet of unetched copper circuit board (buy from radioshack type store) with a wire soldered to it that you attach to the bridge of the guitar. When you want to record you place your bare foot on it to earth you to the guitar.

cheers
john

[guitardad72]

oop I double posted somehow and can't delete the 1st of two.

[guitardad72]

A hollow body electric probally does not help as well.

Just cause it's hollow body doesn't make a difference. In fact most hollow body electrics have humbuckers/ double coils so they should make less noise. Hollow body's have a higher chance of undesired feedback at loud volume, when over compressed or with lots of gain for dirt/overdrive. The "hollow" body picks up more sound>more sustain>higher chance of feedback loop.

I've never enjoyed doing an electrical repair to a hollow body, got to take PU's out to get at anything and jam your hand into PU hole. I have a 335 copy on hanging on the wall I've not live gigged with for 2 years cause it needs new pots. I don't think it's common for hollow bodies to have a shielding around the electrical components like solid body USA Strats (or other guitars) do in there electrical chamber. That's what I was referring to earlier with "more expensive OR well built guitar will be almost noiseless"

BTW I am a Strat man

Here's an excellent web site on DIY shielding an electric guitar and guitar noise problems in general:

http://www.guitarnuts.com/wiring/index.php

John Sayers

I've always had a sheet of unetched copper circuit board (buy from radioshack type store) with a wire soldered to it that you attach to the bridge of the guitar. When you want to record you place your bare foot on it to earth you to the guitar.

I figured out the bare foot thing by accident, had my hand on guitar and touched some metal on gear and noise went away. Requiring my two hands to play, I placed my bare foot on the rack... I've not presumed I'm the only one to figure this out, actually kind of relieved someone else does this too.

But John your method is different then mine I've found the ground path: guitar > body > gear. You're finding the ground: guitar > body > guitar.

Would someone care to elaborate on this bare foot grounding of a guitar in order to overcome guitar noise problem? Would I be correct in saying this would be like the star grounding system: the guitar player becomes the equivalent the grounding bar where we "star" or "home run" attach every ground wire too eliminate the ground loop? OR is it guitar players body mass is enough to ground out the loop?

This topic I find really interesting

Marc

[tmix]

I had a wire with an alligator clip I hooked to the bridge and then slipped a bare end of the wire inside the elastic band of my shorts.

I know.....dont say it!

It is not glamorous by any means but worked on problem guitars.

Tom

[leecow]

If you're running guitars with single coil pickups, it's almost certain to not be adequately shielded or grounded properly from the factory. Visit http://www.guitarnuts.com/index.php for some great information on the topic.

Even with good shielding and star grounding, some single coil rigs will still buzz/hum/etc. I had a Tele that got the full treatment and was dead quiet when used in front of a CRT and only buzzed when playing in an old (100 years) building with same vintage wiring. On the other hand, my Strat is as shielded and cleanly grounded as it can get (without playing inside a Faraday cage) and it still picks up some noise. Ah well, if you love the single coil sound, you have to live with a bit of noise.

Lee