Guitar EMI RFI

Well, I've made a few pounds diagnosing noise issues, and have some kit to do this - scopes and a spectrum analyser, which I use to detect and usual solve interference issues on marine radio systems. I'm quiet aware of the vagaries of EMI and RF noise sources.

The bass was noise sensitive from new - a fairly common problem with jazz basses, and a pickup swap and the usual sticky copper cavity shielding totally cured it. If you can stop your noise with a lump of metal that's great, but as the noise source path is always a straight line, spend some time localising the noise source - move the guitar and see if you can locate it. Common sources I have found are No.1 Switch mode wall wart style power supplies. No.2 network wifi routers. No. 3 Cheap lighting dimmers.

Screening is a tried and tested tool, and some designs are just inherently sensitive to it. Single pole pickups of the Strat type are the worst because their design is looking for the presence of a disturbing force within it's capture area. As in a vibrating string. This leaves them wide open to any other local electro-magnetic fields and in a way, their doing what they were designed to do. My bass picked up the big transformer in my old favourite amp, so the crude cure was put the amp to one side so when I faced the audience the field from the transformer was at right angles to the pole pieces. That's just impractical. The screening helped, but the front of the coils were still unscreened. The side and back routes to the pickups were screened. A change of pickups was the total cure - not to something ultra good and expensive, but ones recommended as being less susceptible to e-m fields.
 
Yesman said:
Hmm i may just try and unplug it really quick and see if it goes away. would be faster to test. Then just plug it back in
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As Spantini has said.....don't just unplug the fridge. Unplug it only when you hear it running....then go and check for the noise.

Mick
 
Mickster said:
As Spantini has said.....don't just unplug the fridge. Unplug it only when you hear it running....then go and check for the noise.

Mick
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I have the guitar plugged in and its making the noise and i am shutting all kinds of things down lol, i'm not that clueless. No change with the fridge unplugged.
 
rob aylestone said:
Well, I've made a few pounds diagnosing noise issues, and have some kit to do this - scopes and a spectrum analyser, which I use to detect and usual solve interference issues on marine radio systems. I'm quiet aware of the vagaries of EMI and RF noise sources.

The bass was noise sensitive from new - a fairly common problem with jazz basses, and a pickup swap and the usual sticky copper cavity shielding totally cured it. If you can stop your noise with a lump of metal that's great, but as the noise source path is always a straight line, spend some time localising the noise source - move the guitar and see if you can locate it. Common sources I have found are No.1 Switch mode wall wart style power supplies. No.2 network wifi routers. No. 3 Cheap lighting dimmers.

Screening is a tried and tested tool, and some designs are just inherently sensitive to it. Single pole pickups of the Strat type are the worst because their design is looking for the presence of a disturbing force within it's capture area. As in a vibrating string. This leaves them wide open to any other local electro-magnetic fields and in a way, their doing what they were designed to do. My bass picked up the big transformer in my old favourite amp, so the crude cure was put the amp to one side so when I faced the audience the field from the transformer was at right angles to the pole pieces. That's just impractical. The screening helped, but the front of the coils were still unscreened. The side and back routes to the pickups were screened. A change of pickups was the total cure - not to something ultra good and expensive, but ones recommended as being less susceptible to e-m fields.
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I did this exact thing. i unplugged the wifi and router and a few other things and didnt help. Although i didnt actually unplugg it from the wall wart side only the dc plug side. I should disconnect the wall wart itself from the power.
 
You mentioned that an 1/8 inch thick piece of aluminum blocks the signal. You never mentioned if it blocks it from both sides of the bass. In other words.....you hear the noise....you move the aluminum in front of the pups...the noise goes away......then in back of the pups/bass body without turning the guitar at all.........what happens? Don't mean to irritate you...just trying to help out. Don't rule out a pup cavity shield install or upgrade.

Mick
 
Mickster said:
You mentioned that an 1/8 inch thick piece of aluminum blocks the signal. You never mentioned if it blocks it from both sides of the bass. In other words.....you hear the noise....you move the aluminum in front of the pups...the noise goes away......then in back of the pups/bass body without turning the guitar at all.........what happens? Don't mean to irritate you...just trying to help out. Don't rule out a pup cavity shield install or upgrade.

Mick
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Its an acoustic guitar with a dimarzio acoustic sound hole pickup. Its a great sounding pickup just getting this issue. I can place the sheet metal somewhere else. where should i place it? I would have to take out the pickup and test putting it behind it to see what happens. The sheet metal is too big to fit behind the sound hole at the moment. I would have to cut it down. Let me trying taking it out and test that.
 
Sorry...for some reason I thought it was a bass.

If the pickup is one of those removable types......that would be easy to test. As well.....while you have it out.....test shield just the portion of wire that goes from the jack to the pup. It could be that as well. And...of course.....you've tested different cords as well right? Sorry if I missed that. Any cheap cords I have seem to pick up noises. The best ones usually won't. Hang in there....you'll solve this.

Mick
 
Mickster said:
Sorry...for some reason I thought it was a bass.

If the pickup is one of those removable types......that would be easy to test. As well.....while you have it out.....test shield just the portion of wire that goes from the jack to the pup. It could be that as well. And...of course.....you've tested different cords as well right? Sorry if I missed that. Any cheap cords I have seem to pick up noises. The best ones usually won't. Hang in there....you'll solve this.

Mick
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I tried under the pickup and didnt have the same effect. When the sheet is over top of it is when it stops the noise. When i disconnect the 3.5MM plug it just does the normal buzz like any guitar cord would do when disconnected. when connected i put the shield over the string path and the buzz still happens. the sheet really only works if block the front of the pickup it self it seems.
 

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spantini said:
Although this is not about acoustic guitar pickups, it does have some interesting reading about the RFI / EMI noise problem and possible causes in a studio environment.

The poster by the name of 'dbbubba' goes into some interesting detail on the subject.

https://gearspace.com/board/so-much...being-picked-up-humbucking-guitar-pickup.html
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Yup looks like he knows his stuff. He understands how buildings function holistically. Its a tough task. Sometimes you cant control where it is coming from as it may not even be in your suite.

In the meantime i will continute to track at buzz free times and see about doing some sheilding to my workspace area. The buzz is not that loud its tolerable but i definitely wont track guitar with it. I dont want to have to process it out as that takes away tone and clarity from the track.

There really is no fix all solution with this stuff.

Will keep yall posted
 
Buzz free time indicates a switched noise source, so pop the pickup out, and use its directionality to find the cause, you seem to be responding to the end result, when if the cause is something you might be able to cure (it could be a utility company transformer that is faulty, but nobody has noticed) it’s a win. In terms of shielding from EM interference, everything metallic had an effect, but some materials work better. Mu-metal often quoted as the best, but one thing is clear. Surface area, density and distance from the transducer is the key. Fender basses ( it was me who mentioned basses, not the OP) used to have their bridge pickup with a metal cover. This was horrible to play but did quiet external noise.
if a one foot square metal panel reduces the noise at a foot away, it becomes a two foot square if you double the distance and gets progressively bigger as it moves away. That’s an entire wall of screening if you need to be able to spin 360 degrees on the spot! Making it smaller means a Fender like cover over the strings so not practical.

find the source and maybe it can be fixed?
 
I have tried that and turned off as many things in the direction it is coming from (That i can control of course) The only other thing i can do is just shut the breakers off but then how would i track without my gear powered? Theres nothing else in my control that i can shut off that could be causing the noise. If its something in another apartment i cant control that. or if its something in the building that switches off and on i cant control that either. That is why i am resulting to blocking the noise instead of running to everyone's apartment and telling them to shut something off lol. But your right it is definitely something switched i just dont know what. and its definitely not in my apartment as it comes and goes even within the same session without me changing anything and i have tested everything. If its a utility transformer that is something i cant control.

In short you are right in that its better to find the source but whatever the source is its not in my control. i cannot stop it on my end. the only thing i can maybe do is move my entire rig away from this adjacent wall i have with my neighbor. its possible they have a lamp or something that is causing it. but even then it might make it all the way to where i put my rig next.

i hear what your saying on the size of metal. I was thinking i just do the back wall that my guitar faces when i record about half way up as it seems to stop the noise when i place the shield in between my guitar and the wall. its about 6.5ft by 5ft area. not too big. I think if i did that little piece it will help alot. Just a hunch though i would have to test that. If that works, i would probably cover a small portion of the adjacent wall as my rig is tucked in a corner.

Again i can rotate the guitar and it drastically goes away but still hear remanences of the noise. with the shield it goes away completely. Turning the guitar sideways the noise seems to sneak in through the side of the pickup somehow. Also I rather block the sound than having to rotate uncomfortably to reduce the noise. when I'm recording for hours on end i want to be comfortable and know that i dont have to have the guitar in a specific spot. That is tremendously annoying when you are trying to get a take down.

I will look into the MU-Metal seems like what i need.


PS. that back wall happens to be my neighbors kitchen. so idk if there is a light or something there that they have on sometimes. Maybe its their fridge that is clicking on and off. who knows
 
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I've had several of the small CFL bulbs that produced horrible buzz. Turn on the light and BUZZZZ.... I pulled one and replaced with an LED and it was silent. If you are in an apartment, it could be a neighbor with some particularly bad lights. The other big offenders that I have found are motors. Since things like A/C compressors, refrigerators, washers and dryers cycle, that's a possibility.

I doubt that it is from a wall wart or other power supply since they would typically be on all the time. You wouldn't have the cycling that the OP mentions. Even a computer power supply will still be active since all computers today have logic controlled soft on/off control, not a physical switch to disconnect the power like in the old days. On the other hand, the computer boards themselves can create EM and RF interference. When fired up and running at full speed, it could be causing the problem. Again, that's hard to track when you are dealing with neighbors in an apartment.

The idea of pulling the pickup from the guitar and using it to narrow down the possible sources is a good one.

I
 
Does this buzz happen on any other guitars with pickups?

At any other location with the same gear?
 
Again i have followed the source to the wall lol. I cant investigate further its not in my apartment. I would say its traveling through the powerline or in my neighbors apartment. i can really only block at this point. I dont think its from a wall wart either nor my pc. I tried putting the pickup close to my pc and it gives me a differenct distinct EMI noise but i have to be really close for it to happen. My pc also has a seasonic very high quality power supply. other than that i turned of my LCD monitors wifi everthing i can think off.



Guys its not in my apartment and i have already moved the pickup around to see if it takes to anything i can pin point and nothing. i trace it to the walls. So lets proceed with the premise that it is outside of my apartment That way i can get some real ideas that may work.

I was also looking into the LR braggs M80 humbucker pickup. but i know i wont like the sound of the pickup and i like the way the one i have sounds. Also i am not certain that it would be immune to the noise just because it is a humbucker. I rather nip this issue at the source
 
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