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Electromagnetic Interference - Help!!

Warrior

Power User
I am trying to pinpoint the source of the EMI that is making it's way into my DAW in my home studio. The funny thing is that if I sit facing my computer monitor with my guitar I get the EMI, turn 90 degrees and nothing as long as I stay within a degree or so of the sweet spot. Now, if I face the monitor and rotate just my guitar 90 degree's (like a clock) the EMI goes away. As long as my guitar is pointed towards the ceiling or floor.

The EMI does not go away when I turn off the computer monitor.

If I face away from the monitor (180 deg) I get the EMI.

Turn all lights off and no difference.

If I am standing close to my dimmer switch the EMI is high as the light ramps up but not when full on or off.

I tried using an AM radio to pinpoint the source of the EMI and found several sources when close. However, if I face away from my monitor I do get the EMI but no lights, monitor are on. I even shut the other lights in the other room off.


I really want to solve this because it is making my recording life insane!

Does anyone know how I can go about this?
 

Greg H

Inspired
I assume you get the interference when you are using headphone plugged into the Axe in addition to whatever you use for a room monitor.
Usually, in RF interference troubleshooting, you would start with turning off everything in the house, one at a time. Including your computer. If it still does it, it's not coming from your house. Most likely it is. Assuming it is not too disruptive for the other people in your house, you can start with turning off all the breakers (except the Axe) and (assuming the noise is gone) turn them on one at a time until you find the noise maker. Then see what is on that circuit. If it still does it with all circuit (other then the Axe) shut off. Move the power source of the Axe to another circuit and shut off the one the Axe was plugged into before.
Using the AM radio is a good troubleshooting method (for those who do not own a spectrum analyzer) but if the noise is radiated through the air (rather then carried by the power lines, changing with your guitars position is a good indicator that it is radiated noise) then the RF can be redirected by other metal objects, such as other power wires or appliances which is a reason you can get false indications in other parts of your room.
The computer is a likely offender. Some of those florescent lights (like the screw-in light replacements) can be very noisy. Light dimmers can be bad but usually turning them off eliminates them as a problem.
That is a start.
Good luck
 

JJunkie

Power User
If your issue is purely defined by what direction your guitar is facing then it is an electromagnetic field (EMF) issue.

I have a gauss meter. Its pretty useful. Everyone says don't use the energy saving lights, but they actually don't emit EMF that is measurable over the ambient levels.

Modern computer monitors don't appear to emit much EMI beyond 0.5m away. Where is your computer tower located? The power supply in it will emit a bit. Are you using anything like a e.g. step-down transformer to power your gear? those will emit a lot but should be OK about 2m away.

I have noticed in some old houses that the ambient levels are just high and get higher the closer the detector is to the ceiling. I suspect it is old/dodgy wiring.

If you have overhead electricity lines in front of your house / studio, depending on the voltage, they can emit EMI quite a long way, e.g. 30m. Overhead transmission lines can emit a lot even from hundreds of metres away.
 

Sean Ashe

Power User
I've unfortunately had/have this issue in my home as well.

I'm 99% sure it's actually the wiring in the walls, i believe there are grounding issues with the main lines.

I have tried everything, turning all the circuits off except for my room, and nothing works. What's very strange is sometimes it goes away.. and other times it is EXTREMELY strong.

if you have the $, I would suggest calling an electrician to come take a look at the wiring in your home.
 

maxdown

Fractal Fanatic
I have tried everything, turning all the circuits off except for my room, and nothing works. What's very strange is sometimes it goes away.. and other times it is EXTREMELY strong.
That could indicate that a device has been turned on elsewhere that is causing the issue - dishwasher, heating boiler, dimmer lights elsewhere in the house, security lights etc etc. It might also be something downline from your house of course - so you'd need to contact the power supplier to see if they can detect where it's coming from.

There are isolation sockets/adaptors you can get which safely isolate the earths if it was an earthing noise issue. Years ago we were recording in a BBC studio and the whitecoated techs put one of these between everything electrical and the power sockets in the studio - standard operating procedure for that studio was all they said .... bet it was because the power was noisy.
 

Sean Ashe

Power User
That could indicate that a device has been turned on elsewhere that is causing the issue - dishwasher, heating boiler, dimmer lights elsewhere in the house, security lights etc etc. It might also be something downline from your house of course - so you'd need to contact the power supplier to see if they can detect where it's coming from.

There are isolation sockets/adaptors you can get which safely isolate the earths if it was an earthing noise issue. Years ago we were recording in a BBC studio and the whitecoated techs put one of these between everything electrical and the power sockets in the studio - standard operating procedure for that studio was all they said .... bet it was because the power was noisy.

It's not the gear picking it up from the sockets, it's being picked up by the pickups as its in the air.
 

dabert

Member
In my case it is an electric cattle fence in the neighborhood that I pick up with P90s in form of a click every 1.2 seconds or so (noticable when not playing or when paying attention to it). Before, there was a short in the fence (metal touching metal) and I could pick up the click even with humbuckers.

There is a sweet spot that I have to hit exactly in my room to get the lowest noise and click ratio (actually no click). Lucky for me, that spot is convenient and I do not have to stand on a desk or something.

Before I figured it to be the fence it drove me nuts and I really tested every piece of electrical gear in my house. EMI sucks big time! (and I do not mean that in a Sex Pistols kind of way).
 

Warrior

Power User
I assume you get the interference when you are using headphone plugged into the Axe in addition to whatever you use for a room monitor.
Nope. It does it with or without headphones.

Usually, in RF interference troubleshooting, you would start with turning off everything in the house, one at a time. Including your computer. If it still does it, it's not coming from your house. Most likely it is. Assuming it is not too disruptive for the other people in your house, you can start with turning off all the breakers (except the Axe) and (assuming the noise is gone) turn them on one at a time until you find the noise maker. Then see what is on that circuit. If it still does it with all circuit (other then the Axe) shut off. Move the power source of the Axe to another circuit and shut off the one the Axe was plugged into before.
Using the AM radio is a good troubleshooting method (for those who do not own a spectrum analyzer) but if the noise is radiated through the air (rather then carried by the power lines, changing with your guitars position is a good indicator that it is radiated noise) then the RF can be redirected by other metal objects, such as other power wires or appliances which is a reason you can get false indications in other parts of your room.
The computer is a likely offender. Some of those florescent lights (like the screw-in light replacements) can be very noisy. Light dimmers can be bad but usually turning them off eliminates them as a problem.
That is a start.
Good luck
I'll try shutting circuits down but I don't think it's an RF issue.

Most LCD monitors use fluorescent back lights, which are huge sources of EMI.
I have the EFI with the LCD off.

If your issue is purely defined by what direction your guitar is facing then it is an electromagnetic field (EMF) issue.

I have a gauss meter. Its pretty useful. Everyone says don't use the energy saving lights, but they actually don't emit EMF that is measurable over the ambient levels.

Modern computer monitors don't appear to emit much EMI beyond 0.5m away. Where is your computer tower located? The power supply in it will emit a bit. Are you using anything like a e.g. step-down transformer to power your gear? those will emit a lot but should be OK about 2m away.

I have noticed in some old houses that the ambient levels are just high and get higher the closer the detector is to the ceiling. I suspect it is old/dodgy wiring.

If you have overhead electricity lines in front of your house / studio, depending on the voltage, they can emit EMI quite a long way, e.g. 30m. Overhead transmission lines can emit a lot even from hundreds of metres away.
No overhead electric lines in the neighborhood.

Turn off your monitor. Does the noise level drop?
Nope.

I've unfortunately had/have this issue in my home as well.

I'm 99% sure it's actually the wiring in the walls, i believe there are grounding issues with the main lines.

I have tried everything, turning all the circuits off except for my room, and nothing works. What's very strange is sometimes it goes away.. and other times it is EXTREMELY strong.

if you have the $, I would suggest calling an electrician to come take a look at the wiring in your home.
If I can locate an electrician that specializes in studio wiring, I might just do this.
 
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maxdown

Fractal Fanatic
Power supplies can be culprits too - such as external ones for phone charging, computers (internal and external ones), monitors etc.

Best bet to check is to turn everything off and remove all from the wall sockets except the Axe and use headphones to see if it's still there ... if it improves then start plugging other stuff in sequentially to see when it reappears.

An old G4 MacBook I owned had an unbelievably irksome power supply - a new power supply from the Apple Store fixed that
 

Warrior

Power User
Power supplies can be culprits too - such as external ones for phone charging, computers (internal and external ones), monitors etc.

Best bet to check is to turn everything off and remove all from the wall sockets except the Axe and use headphones to see if it's still there ... if it improves then start plugging other stuff in sequentially to see when it reappears.

An old G4 MacBook I owned had an unbelievably irksome power supply - a new power supply from the Apple Store fixed that
I'll give this a try but I did take my Axe-FX to a different room upsatairs, plugged in the headphones and still had the noise.

What happens to the noise when you unplug your guitar cable from the Axe's front panel?
I'll have to try and let you know. I don't recall.
 

Warrior

Power User
OK.... more questions about "Symptoms" and trying to find the source of my noise.

If I unplug my guitar (at the guitar) and move my guitar cable around I get variations in the noise.; much like when I have the guitar plugged in and move around. Is this normal?

Wondering now if it's some other issue.... other than EMI?

Also, I notice the noise is less when I have my bridge PUP in parallel compared to hum bucker.

Here's the WAV form

 
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Rex

Legend!
What happens to the noise when you unplug your guitar cable from the Axe's front panel?
 

Zwiebelchen

Fractal Fanatic
If I unplug my guitar (at the guitar) and move my guitar cable around I get variations in the noise.; much like when I have the guitar plugged in and move around. Is this normal?
That actually shouldn't happen, except if you cable has a magnetic pickup. ;)

Have you tried using a different cable?


Do you have a WLAN router in your house? If so, have you tried turning it off? Just asking, because sometimes the most obvious issue tends to be forgotten...
 
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