EMI Shielding
« on: March 11, 2019, 12:02:05 PM »
Not sure if this is the right area for this post.  My project studio in my garage has a strong magnetic field getting into my single coil pickups of my fender guitars and bass.  I can adjust my position to find the null point, but that is getting old staying in one position.  I've tracked the offending item to the overhead feed from the power lines to my neighbors main electrical panel.  If I move into my house away from the power lines, the interference goes away.   When I'm directly underneath holding the guitar at the exact angle of the power lines overhead, the noise is at it's greatest.  The null is when the guitar is perpendicular to the lines.

As a test, I've got a 4x10 foot roll of sheet metal that I've wrapped in a circle standing on end and placed one of the fender guitars in with it plugged into an amp and the noise disappears.   I'd like to wrap my room with the sheet metal as it's fairly small, 10x8x8, to eliminate the interference all together, but wanted to ask here first if there are any other options to shield this interference.  I've tried shielding the cavity of one the guitars but that didn't work.

Thanks for any help here.   Considering contacting Edison, the electrical company, to see if this is normal.  I'm just not sure how to go about talking with them about it.  Maybe I need to get a gauss meter or something like that.

Nate


JohnRoberts

Re: EMI Shielding
« Reply #1 on: March 11, 2019, 01:10:24 PM »
https://repforums.prosoundweb.com/index.php?topic=33770.0

here is an old discussion, may be easier to shield the guitar pickup...

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

Re: EMI Shielding
« Reply #2 on: March 11, 2019, 01:51:49 PM »
So I've already tried the pickup shielding but that didn't work.   The only thing that works is placing the guitar in a sheet metal cylinder.  I've got a roll of sheet metal that is wrapped around the guitar and clamped together.  Right when the guitar pickups enters the metal cylinder as I drop the guitar in from the top, the noise goes away.  I also tried metal mesh but that didn't work for the shielding...

ruffrecords

Re: EMI Shielding
« Reply #3 on: March 11, 2019, 02:24:01 PM »
Solid sheet metal is not cheap and it is heavy.  Have you tried using the kind of steel netting typically used for the front of a rabbit hutch.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

dmp

Re: EMI Shielding
« Reply #4 on: March 11, 2019, 04:18:23 PM »
Sounds like a Faraday Shield / Cage or magnetic shield . A mesh should work as well as a solid sheet for some types of interference.  If it is magnetic interference, you need magnetic shielding.  Since a mesh didn't work and the sheet metal is, it sounds more like magnetic interference.
https://en.wikipedia.org/wiki/Electromagnetic_shielding

Sounds like the roll of sheet metal is redirecting the flux around the guitar. Does it work in all orientations? i.e. if the roll of sheet metal is horizontal and you move the guitar in (with the guitar aligned along the axis of highest interference).

I would do a few more tests so you are confident shielding the whole room will solve the problem.


radardoug

Re: EMI Shielding
« Reply #5 on: March 11, 2019, 04:38:40 PM »
Or you could just buy humbucking pickups! Why are guitarists stuck in the dark ages?

pucho812

Re: EMI Shielding
« Reply #6 on: March 11, 2019, 06:10:46 PM »
Or you could just buy humbucking pickups! Why are guitarists stuck in the dark ages?

because single coil pickups despite having noise issues sound really good  8)
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

dmp

Re: EMI Shielding
« Reply #7 on: March 11, 2019, 06:26:35 PM »

How about midi triggered guitar sounds from your laptop? (sarcasm) 

i tried a fender  'noiseless' pickup and it did not sound as good.

Re: EMI Shielding
« Reply #8 on: March 11, 2019, 06:29:40 PM »
The interference is gone when laying down the roll of sheet metal and sliding the guitar in.   Again, the guitar is positioned in parallel or on the same axis as the power lines above the studio.  I have a gauss meter arriving later today so I will try it out.  Never used one before. 

As far as changing the pickups...I could do that in my tele and jazz bass, but my strat is a vintage family hand me down and I'm not authorized to modify it....only play and store it.

Re: EMI Shielding
« Reply #9 on: March 12, 2019, 12:09:43 AM »
Well the EMF or Gauss meter didn't show me much.  I tried sitting in the position I would normally sit in while playing my guitar/s and went around in a full circle.  The meter didn't show really anything.   So I placed it around my computers and some other household electronics and the meter went off like crazy.  So I know it works.  The meter says it will measure 30-300hz so maybe I'm dealing with some other kind of frequency.


radardoug

Re: EMI Shielding
« Reply #10 on: March 12, 2019, 12:41:23 AM »
Seymour Duncan makes good humbuckers, and he's a good guy and a good guitarist. You should try them before going down the current rathole.

Re: EMI Shielding
« Reply #11 on: March 12, 2019, 05:38:43 PM »
Decided not to cover my room in sheet metal...I didn't want to finish and find out that it didn't work.

So I ordered the Seymour Duncan Vintage Stack pickups for my telecaster and the Apollo Jazz Set for my jazz bass.  I also ordered some Fender Vintage Noiseless pickups for my strat.   Now all of my single coil guitar/s will be noise free or quieter than they currently are.  Thanks for the help here.

Nate


radardoug

Re: EMI Shielding
« Reply #12 on: March 12, 2019, 06:20:01 PM »
I think you will be happy with the Seymour Duncans, but report back to us here from the guitarists perspective. As a sound man, I hate hearing my music with hum.

dmp

Re: EMI Shielding
« Reply #13 on: March 12, 2019, 06:24:17 PM »
Quote
I also ordered some Fender Vintage Noiseless pickups for my strat.   

my strat is a vintage family hand me down and I'm not authorized to modify it

Depending on how vintage and original the strat is you might want to get an expert opinion before modifying it.

Squeaky

Re: EMI Shielding
« Reply #14 on: March 12, 2019, 09:34:40 PM »
As a guitarist first and foremost, my quite strong opinion is as as follows: single coil pickups are certainly noisier than humbuckers but they can sound absolutely divine and have a sound and response that humbuckers do not have (at least in my experience). I will never, ever mod my current (probably for life) strat  with humbuckers (been down that road in my youth when I couldn't play a strat properly - it was a '79 strat and a dog of a guitar admittedly). Many times I have had to sit patiently at a certain angle when recording in order to cancel the hum. I always treated it as a relatively minor inconvenience. Volume rolls can be challenging.

JohnRoberts

Re: EMI Shielding
« Reply #15 on: March 12, 2019, 10:38:28 PM »
Indeed a humbucker is a different sound.

Maybe you need to build an isolation booth out of steel...

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

Re: EMI Shielding
« Reply #16 on: March 12, 2019, 10:40:55 PM »
Ive seen a lot of different pickups , I never liked the noiseless strat pickups ,ok you get noise reduction ,but tone isnt as good as the real strat pickups .
Active set ups can beat noise down ,but I just find theres a roundness of tone missing from them too.

SCR lighting dimmers are possibly the worst offenders in a gig situation ,bigger venues will have the electric supply properly done to avoid noise , smaller venues generally dont .

Worst I saw was one time some of my pals played a gig , one of the mains outlets was detached from the wall ,and the earth must have broken , one of the guitar amps was picking up so much hash ,the anodes glowed red hot , yet no one in the band or audience was hearing anything wrong, I managed to take a look on the break ,and find a properly earthed socket and I informed the owners of the potentially deadly situation onstage .

What sort of lighting do have your in your studio ? could it be contributing to noise ,
Could an earthed  metal conduit be used along the ceiling where the wires are to contain the ethereal buzz?


radardoug

Re: EMI Shielding
« Reply #17 on: March 12, 2019, 11:22:19 PM »

Could an earthed  metal conduit be used along the ceiling where the wires are to contain the ethereal buzz?

Its a magnetic pickup, picking up a magnetic field! A conduit on the roof wont do f*** all!

Re: EMI Shielding
« Reply #18 on: March 12, 2019, 11:49:44 PM »
Well he did see some reduction in noise by screening the guitar , so the metal must doing  something .

radardoug

Re: EMI Shielding
« Reply #19 on: March 13, 2019, 01:28:30 AM »
Read it properly. You have to surround the guitar. Not very practical.


 

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