Shielding pickups

[kevinT]

Once and a while, I'll receive radio signals when i'm playing the geetar and i am thinking that shielding the coils with copper conductive foil tape might help prevent this from happening especially on high output pickups, which seem to be more prone to it.

Seymour uses conductive tape on his Duncan Custom model which is a high output ceramic pickup. Before disecting the pickup to find out what is going on, i was wondering if anyone has any experience with shielding humbuckers?

Do you just wrap the tape around the coils and it shields the pickup from noise? Or, do you have to solder a lead from the tape to the baseplate to ground it?

[Spence]

That's not radio kevin. It's the voices in your head.
But if you want to do some shielding you can use the self-adhesive copper foil from AllTwats. You can do a complete wrap as the adhesive insulates the layers. I always cut a little leg in the final part of the wrap that I then solder to ground.

[David King]

You can do a complete wrap as the adhesive insulates the layers.

most real copper shielding tape comes with conductive adhesive. Then again I don't care about eddy currents on my basses.

[black_labb]

why not put a bit of electrical tape to insulate the overlap? thats what i plan on doing.

[Joe Gwinn]

Once and a while, I'll receive radio signals when i'm playing the geetar and i am thinking that shielding the coils with copper conductive foil tape might help prevent this from happening especially on high output pickups, which seem to be more prone to it.

You have a loose connection somewhere, and it's acting as a rectifier diode. Make sure all solder joints are solid, and all mechanical joints are tight.

[Possum]

...

I use copper tape that stained glass crafts people use, works real well. Its useful to darken up bright pickups, solder the tape closed and solder to ground and it kills alot of high end....

[soundmasterg]

This problem could also be coming from your amp.

Inside the amp there is usually a 68k resistor on the input that is supposed to supress those type of signals. Unfortunately the manufacturers often don't install these resistors correctly and the amps are then susceptible to radio frequency interference. These resistors should be installed as close to the tube socket as possible and they are almost always installed on the board or at the input instead, where they don't really do much good.

Greg

[Possum]

....

Could be your guitar/pickups or your amp. Can you get these signals only with a certain guitar, can you get them with the guitar unplugged from the amp? I've gotten them before only using a certain gain pedal, could be anything, isolate each part first....

[greenfingers]

Paint it black

To keep the electronics properly shielded you can give the pickup pockets in the guitar body a coat of graphite based screening paint.

[Earl Norton]

Make double sure you don't use a speaker cable for an instrument cable. That will do it every time.

[PoorMan]

That's not radio kevin. It's the voices in your head.
But if you want to do some shielding you can use the self-adhesive copper foil from AllTwats. You can do a complete wrap as the adhesive insulates the layers. I always cut a little leg in the final part of the wrap that I then solder to ground.

Does this increase capacitance dramatically?

[David Schwab]

Does this increase capacitance dramatically?

If you wrap the foil all the way around the coil, so it's a closed loop, it will take some high end off the tone because it's generating eddy currents. If you leave a split, or insulate the two ends so they don't touch, that will prevent the problem. This is true of metal covers that wrap all around the coil too.

As Possum pointed out, you can use this to warm up an overly bright pickup.

[PoorMan]

If you wrap the foil all the way around the coil, so it's a closed loop, it will take some high end off the tone because it's generating eddy currents. If you leave a split, or insulate the two ends so they don't touch, that will prevent the problem. This is true of metal covers that wrap all around the coil too.

As Possum pointed out, you can use this to warm up an overly bright pickup.

Interesting. So if the foil is not a closed loop (even though you ground it) this keeps the highs from bleeding to ground?

[David Schwab]

Interesting. So if the foil is not a closed loop (even though you ground it) this keeps the highs from bleeding to ground?

Yeah, it actually has nothing to do with ground. it's eddy currents. When you have a conductor in the presence of a magnetic field a current will flow... this is obvious, since that's how we get the current flowing in the copper wire. With eddy currents, they are small swirling currents on the surface of the conductor, and these currents produce their own small magnetic field which opposites the main field. This is what kills the high frequencies.

There's actually an old patent by Rowe that shows a metal open top pickup cover, with a slit though one side to stop this from happening.