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High-shielded cables and EMI noise

rrhoads17

Member
I noticed if I stand on the other side of the room in a certain spot it kills down the noise. But if I turn it back towards the computer/screen/studio monitors it goes a little crazy. But it's odd because when I turn all of that stuff off there's still noise there. And I noticed if I aim my guitar near the brass locks on my door the noise goes away completely.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
I noticed if I stand on the other side of the room in a certain spot it kills down the noise. But if I turn it back towards the computer/screen/studio monitors it goes a little crazy. But it's odd because when I turn all of that stuff off there's still noise there. And I noticed if I aim my guitar near the brass locks on my door the noise goes away completely.
Classic EMI. There's a power supply or transformer somewhere radiating.
 

Tommy Tempest

Power User
I noticed if I stand on the other side of the room in a certain spot it kills down the noise. But if I turn it back towards the computer/screen/studio monitors it goes a little crazy. But it's odd because when I turn all of that stuff off there's still noise there. And I noticed if I aim my guitar near the brass locks on my door the noise goes away completely.
Noise interference can come from many different components. Since I use a 25 ft. 13 pin midi cable, when it starts to go bad, I will pick up noise dragging it on a concrete floor. As it slides across the floor, over the wire mesh in the concrete, it creates static and sparkles. I know it's time to replace. And since my Graphtech Ghost systems, installed in my guitars, have their own preamp, embedded in the guitar, keeping my cellphone in my pocket causes alien sci fi sounds.
 

Warrior

Power User
I've been considering shielding my Strat cavity with copper. I don't like the idea of possibly losing the highs from wrapping my single coils.
Is it a wasted effort if I only shield the cavity?
 

rrhoads17

Member
Maybe I have bad cables? They are pretty old. And I'm assuming wireless would make even more noise than cables. The only transformer that I know of is the elevator transformer down the hall but it doesn't seem to be noisier if I point it in that direction.
 

Rex

Legend!
I've been considering shielding my Strat cavity with copper. I don't like the idea of possibly losing the highs from wrapping my single coils.
Is it a wasted effort if I only shield the cavity?
No, you won't be wasting your time if you just shield the cavity. But you won't lose any highs by shielding the pickup cavities, too (you don't wrap the actual pickups).
 

rrhoads17

Member
Idk if this would work or not, but what if I put a small metal object between my guitar and the computer and studio monitors? I read on a forum where a guy had this issue and he noticed if he put a metal omelet pan over his pickups, the noise went away. I obviously dont wanna put cookware around my equipment, but putting something metal as a shield may work.
 

fractalz

Power User
Would this be outside or are you referring to items inside the home?
Could be outside. I had terrible EMI from my electrical box and a transformer outside the house.

Get a cheap AM radio, tune it to static and aim it around. It'll tell you where it is coming from.
 

fractalz

Power User
Idk if this would work or not, but what if I put a small metal object between my guitar and the computer and studio monitors? I read on a forum where a guy had this issue and he noticed if he put a metal omelet pan over his pickups, the noise went away. I obviously dont wanna put cookware around my equipment, but putting something metal as a shield may work.
I think the best you'll be able to do is figure out which way to aim your guitar to minimize the noise.

I went all out on my recent studio build and surrounded the space with conductive material. Nothing gets in or out. No EMI, but also no WiFi or cellular signal.

https://www.gearslutz.com/board/pho...sound-pdx-wes-lachot-design-build-thread.html
 

AdmiralB

Experienced
Ultimately you can't shield against EMI everywhere, because the 'M' means magnetic - if you shield the pickups from magnetic fields, you won't get any string signal.
 

solo-act

Fractal Fanatic
I have one gig where headset wireless, electric wireless & pickups, acoustic cable and pickups are each bringing in something with a high whine that only diminishes at a very specific angle. Whatever it is, it's broadcasting over about a 1/2 city block radius and only exhibiting at this one gig...bizarre.
 

Warrior

Power User
No, you won't be wasting your time if you just shield the cavity. But you won't lose any highs by shielding the pickup cavities, too (you don't wrap the actual pickups).
According to the instructions for the StewMac kit, you shield the coils and replace the wiring, etc. That's why I was asking about it.

"Wrap the coil with a strip of black electrician's tape. Start in the area of the two lugs on the lower bobbin plate and be sure to overlap the tape at least 1/2". Prepare to wrap the coil with the 1/2" copper foil tape by trimming it down to 7/16" then cutting a piece long enough to wrap once around the windings and overlap itself by 1/4". Remove all but 1/2" of the protective backing and start to wrap the foil around the bobbin. Start with the end of the foil that still has 1/2" of backing on it in the area of the solder lugs. Wrap the tape around the bobbin and overlap it over the part that still has the paper backing. From outside to inside in the area of the wire lugs you have the following layers: foil, foil, paper backing, black tape, black tape, windings. The paper is left in the area of the overlap because it reduces the risk of getting the area too hot when soldering and shorting out the windings. Before soldering you will want to check to be sure the cover can still be installed."
 

Rex

Legend!
According to the instructions for the StewMac kit, you shield the coils and replace the wiring, etc. That's why I was asking about it.

"Wrap the coil with a strip of black electrician's tape. Start in the area of the two lugs on the lower bobbin plate and be sure to overlap the tape at least 1/2". Prepare to wrap the coil with the 1/2" copper foil tape by trimming it down to 7/16" then cutting a piece long enough to wrap once around the windings and overlap itself by 1/4". Remove all but 1/2" of the protective backing and start to wrap the foil around the bobbin. Start with the end of the foil that still has 1/2" of backing on it in the area of the solder lugs. Wrap the tape around the bobbin and overlap it over the part that still has the paper backing. From outside to inside in the area of the wire lugs you have the following layers: foil, foil, paper backing, black tape, black tape, windings. The paper is left in the area of the overlap because it reduces the risk of getting the area too hot when soldering and shorting out the windings. Before soldering you will want to check to be sure the cover can still be installed."
StewMac says that this isn’t as effective as shielding the guitar, and I think they’re right. But still, they’re shielding the windings, not the entire pickup.
 

rrhoads17

Member
Would a Wifi router cause alot of EMI if its right beside of my rig? I've noticed if I use my cable to gauge noise, I get a lot of noise when I put it around my router whether its on or off.
 

Rex

Legend!
Would a Wifi router cause alot of EMI if its right beside of my rig? I've noticed if I use my cable to gauge noise, I get a lot of noise when I put it around my router whether its on or off.
Wi-Fi routers are some of the worst offenders in the house. It’s surprising, though, that it would cause EMI when turned off.
 

fractalz

Power User
Would a Wifi router cause alot of EMI if its right beside of my rig? I've noticed if I use my cable to gauge noise, I get a lot of noise when I put it around my router whether its on or off.
Have you tried a different cable? Guitar cables are shielded and shouldn't allow EMI in...
 
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