How to shield a single coil pickup?

[voodoochild]

Hello,

I hear about some manufacturers who claim they can shield the single coil pickups without affecting the tone. I have tried the foil strip to ground across the magnets and that deffinately affected the tone. If anyone has a suggestion I would like to know. Thanks in advance.

[David Schwab]

Grounding the magnets shouldn't affect the tone, but wrapping foil around the coil will.

I don't make single coils, but I do know that grounding the magnets and poles on my humbuckers doesn't change the tone.

Here's how one maker shields their pickups...

(that's brass screen!)

[black_labb]

whats the best way to ground the magnets anyway? i assume solderinga wire to them would quite seriously effect the magnet (nevermind the plastic i have used for the bobbin). would pushing a wire against them and supergluing it there ground it properly, or would you think that the superglue would find its way between and act as an insulator. im sure i could do a dodgy job with electrical tape, but i assume there is a better way that is a bit more permanent.

thanks

[Liam]

Pretty sure the superglue would insulate, it will definitely get between the wire and the magnet. Haven't got a good answer though...

[Joe Gwinn]

whats the best way to ground the magnets anyway? i assume solderinga wire to them would quite seriously effect the magnet (nevermind the plastic i have used for the bobbin). would pushing a wire against them and supergluing it there ground it properly, or would you think that the superglue would find its way between and act as an insulator. im sure i could do a dodgy job with electrical tape, but i assume there is a better way that is a bit more permanent.

Use the silver-bearing glue used to repair PB board traces to make the connection between magnet and grounding wire or foil.

[Spence]

Actually, wrap the coil in self adhesive copper foil with a short 'leg' soldered to the earth eyelet.
The self adhesive foil is available through AllParts amongst others.

[voodoochild]

It could be in my head, but I really did think using the foil across the magnets did affect the tone. From what I heard it sounded different to me like it sorta sucked the life out of the pickup some. If it worked without changing the tone then why doesn't everyone do standard? Everyone hates hum.

[David Schwab]

whats the best way to ground the magnets anyway? i assume solderinga wire to them would quite seriously effect the magnet (nevermind the plastic i have used for the bobbin). would pushing a wire against them and supergluing it there ground it properly, or would you think that the superglue would find its way between and act as an insulator. im sure i could do a dodgy job with electrical tape, but i assume there is a better way that is a bit more permanent.

thanks

Here's how Nordstrand pickups does it.

You can also wrap some copper coil around the magnets before you wind them, but don't let the ends of the foil touch... in other words don't make a closed loop. That might affect the tone.

[dai h.]

cool pic. I guess that would be conductive adhesive on the copper foil? How much of a difference does something like that make to the reduction of noise?

[David Schwab]

cool pic. I guess that would be conductive adhesive on the copper foil? How much of a difference does something like that make to the reduction of noise?

If the magnets are not grounded, and you touch them, or even if you have your hand near them, they will pick up hum.

All the metal parts are grounded in humbuckers.

[David King]

It's not clear to me that grounding magnets does much at all to reduce noise. However I like the conductive adhesive copper tape (Chomerics et al) provided you can keep external pressure on the tape from below. If you use the old-school neoprene foam blocks under the magnets that will keep the connection viable. Just sticking the tape on there lasts about 5 minutes.
I like Joe Gwinn's conductive epoxy technique even better but the shelf life of that stuff is about 6 months and it's not cheap.

Personally I would not connect the magnet or shielding drain to the end of the coil. Keep them separate until you get to the output jack. I've been spraying the insides of my plastic covers with MG Chemicals "Super-shield" nickel conductive paint and connecting that to the magnet drain wire with copper foil. I also spray the inside of my pickup routs and connect all that to the bridge and cavity with more paint.

[dai h.]

thx. That makes sense since my understanding is that generally metal bits should not be left floating and I gather especially so in certain situations like parts of the PU and say a metal pot cover but trying to think why the noise reduction happens in this case but I don't quite understand what is going on. When you touch an ungrounded polepiece would you be capacitively coupling hum to the coil (and not when they are grounded)? My head hurts.

[David Schwab]

It's not clear to me that grounding magnets does much at all to reduce noise.

You wont notice much noise until you get your fingers close to the magnets.

We ground the strings for the same reason. Metal parts are like antenna.

Personally I would not connect the magnet or shielding drain to the end of the coil. Keep them separate until you get to the output jack.

That's the best way. They can connect to the rest of the instrument's ground or shield, but keep the pickup common separate as long as you can.

[Joe Gwinn]

It's not clear to me that grounding magnets does much at all to reduce noise. However I like the conductive adhesive copper tape (Chomerics et al) provided you can keep external pressure on the tape from below. If you use the old-school neoprene foam blocks under the magnets that will keep the connection viable. Just sticking the tape on there lasts about 5 minutes.

There are copper foil tapes with conductive adhesive that ought to work for a year, until the adhesive drys out.

I like Joe Gwinn's conductive epoxy technique even better but the shelf life of that stuff is about 6 months and it's not cheap. ... I've been spraying the insides of my plastic covers with MG Chemicals "Super-shield" nickel conductive paint and connecting that to the magnet drain wire with copper foil. I also spray the inside of my pickup routs and connect all that to the bridge and cavity with more paint.

This shielding spray would work to ground magnets as well. The sheet resistance of the dried shielding paint is high enough to prevent eddy currents.

[David Schwab]

This shielding spray would work to ground magnets as well. The sheet resistance of the dried shielding paint is high enough to prevent eddy currents.

That's good to know!