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Talk to me about EMFs

Scott Lynch

Scott Lynch

Supporting Member
Nov 27, 2002
1,490
1,884
#1
My wife and I recently moved into a new home. It's been an adventure, in many wonderful ways, but there have also been some challenges.

One issue I am trying to solve in our new home is to figure out where a good place would be to put our music studio. Unfortunately, in just about every room in the house that's been a feasible location, I've been having issues with EMF noise through my bass and guitar. Some rooms are worse than others (the first location I decided on happened to be the noisiest room, haha!) but in every case, if I turn an instrument a certain way, there's inevitably a hum that is transmitting through the pickups. Although I could probably live with just sitting in a direction that cancels out most of the hum, turning down my tone knob, etc., I'd like to see if there are some things I can do to make my studio setup more guitar friendly.

What are some ways I can mitigate this issue? What have you tried in your own homes that has worked for you? Any resources to share that explains this issue in layman's terms?
 
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#2
If it's in every room you move your recording gear to - then maybe it's your recording gear. Move away from the computer.

If you have ground lift on your interface of DI, try that.

It may be your lighting. Do you have dimmers everywhere? Maybe "smart" switches that also dim?

Try to find out if it is 60hz, or 120hz, or includes other harmonics of 60hz.
60hz would likely not be from amplifier power supplies. 120hz could be from a rectified power supply (line voltage power supply bridged diodes). Other higher harmonics can come from Dimmers, CFL's, LED power supplies.

Power conditioners won't help. Don't go there. If you plug in a power conditioner and your gear works better, then your gear is broken.
 
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#3
Thank you, @seamonkey. I have not hauled my Mac and audio interface all over the house, but have been testing with instruments and amplifiers. How can I test to see if it’s 60 hz, 120 hz, etc.?
 
#4
upload_2023-1-29_19-3-20.jpeg
 
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#5
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#6
Got it, thank you. To provide some more info, I am not getting definable hum but broad spectrum noise. I highly doubt that it is from any fault in my equipment - I gig often and rarely have this problem, and when there is noise coming from my amp on gigs it usually has to do with crappy power at the venue, like being plugged into a circuit with lights on dimmers.

The broad frequency noise is directional, as in if I face a guitar or bass in one direction it is at its most audible, but when I turn 90 degrees it is barely audible or gone. The noise also diminishes when I roll off the tone control, which very much leads me to believe that my pickups are sensing some kind of magnetic field somewhere. Additionally, I should add that while my guitar has true single coils, my bass has noiseless pickups in it.
 
#7
I was getting quite a bit of hum in my amps, seems the power circuit in my house is particularly noisy. I ended up purchasing a pair of these one for my office where I have a couple of small practice amps and another for my pedal board and amp in my studio. While not perfect it made a significant difference in noise reduction. Mine was noise as soon as the amp was turned on and not directional. I purchased mine from Amazon for about $24.

Good luck with it, it can be frustrating. I'm going to upgrade the power to my shed\studio down the road and will try my best to isolate and ground the circuit. The Furman power string was an inexpensive improvement.
Cheers...

 
#9
You’re wide open… Baby monitor? Do you use repeaters for Wi-Fi? Are your light switches dimmers? I’m assuming that as a new home, an inspector would have checked your grounding at your box, but individual outlets mebbe not. Are there overhead power lines nearby? If you want to be absolutely certain, you could isolate one outlet, identify the breaker, turn off ALL other breakers and see if you’ve got the hum. This would eliminate ambient hum, and point to your rig.
 
#11
Is it E or M? Electrical or Magnetic? If you can affect the sound by facing one way vs another, it may be magnet being picked up by the pickups and improving it through shielding & grounding isn't very effective if I understand correctly.

I had issues with a bass several years ago. It improved with 100% copper shielding in the control cavity AND the pickup cavity, wired together and grounded, but it didn't disappear completely. I just learned to live with it at home (face that way to reduce it) and on my gigs never had a problem.
 
#13
Can you hear it on recordings? I record loud guitars while the wife uses the treadmill. But the treadmill motor creates a slight noise when I track. She told me just to embrace it as an effect that no one else will be able to pin down.
 
#14
If you can null the hum - make it pretty much go away from a certain orientation of your bass, then it's magnetic hum, and hum cancelling pickups are the fix - single coil pickups will hum in this scenario, and there is no amount of shielding that will fix that.

If it doesn't go away with orientation, then it's most likely electrostatic, and shielding is the answer. A lot of places, you will have both. If you have both, I'd suggest putting in hum cancelling pickups first, then shielding. If you do it in that order, when you're doing shielding (which is the tougher thing to do right), you'll only be dealing with one problem.

Living in a house with a lot of hum is actually a blessing (once you get past the initial cursing) - it makes you figure out how to make your bass quiet. As a result, you can go to a gig, and not be surprised by how noisy your bass is. The company I worked for for decades was located very close to a high power AM radio station. We made audio gear. We had a reputation for making stuff that was bulletproof as far an interference goes - those two things are not a coincidence, the radio station actually gave us an advantage.
 
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#18
micguy said:
If you can null the hum - make it pretty much go away from a certain orientation of your bass, then it's magnetic hum, and hum cancelling pickups are the fix - single coil pickups will hum in this scenario, and there is no amount of shielding that will fix that.

If it doesn't go away with orientation, then it's most likely electrostatic, and shielding is the answer. A lot of places, you will have both. If you have both, I'd suggest putting in hum cancelling pickups first, then shielding. If you do it in that order, when you're doing shielding (which is the tougher thing to do right), you'll only be dealing with one problem.

Living in a house with a lot of hum is actually a blessing (once you get past the initial cursing) - it makes you figure out how to make your bass quiet. As a result, you can go to a gig, and not be surprised by how noisy your bass is. The company I worked for for decades was located very close to a high power AM radio station. We made audio gear. We had a reputation for making stuff that was bulletproof as far an interference goes - those two things are not a coincidence, the radio station actually gave us an advantage.
Click to expand...

Thank you for the input.

What if I’m getting directional hum, but my instrument has hum cancelling pickups in it?
 
#19
Scott Lynch said:
Thank you for the input.

What if I’m getting directional hum, but my instrument has hum cancelling pickups in it?
Click to expand...

Good hum cancelling pickups won’t do that, provided they’re a few feet or more from the source. If you’re really close to the source, the field is a bit different at each coil, so the cancellation isn’t perfect.
 
#20
Ok, progress -

Yesterday I plugged by bass into my amp, hit the power switch and pointed my bass in the direction of the hum. Then I systematically switched each breaker in our electrical panel off, then on, to see if there would be any reduction in hum. Lo and behold, there were two breakers that, when switched off, resulted in a substantial, almost complete reduction in noise. They were the ones that controlled most of the lights on the first floor, which are controlled by dimmer switches.

A previous owner went to town installing recessed lighting throughout the house, mostly on the first floor. There are a total of five dimmer switches controlling different banks of lights. So my question now - is it possible to upgrade the switches to something that does not hum like these do, or is the only solution to a) turn dimmers off when recording and b) reinstall regular on-off switches for more frequently used lights?
 

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