Shielding a single coil

[voodoochild]

Hey guys,

I am building a strat for someone who wants single coils but with the least hum possible. He doesn't want humbuckers either. I tried talking him into the Suhr backplate but it was too pricey. That said I am thinking of shielding the coils but I don't know if I should just wrap copper shielding around the outside and connect to ground or should I wrap the inside around the magnets and the outside of the coil connecting both to ground. I would think that shielding inside and outside of the coil would be best although I have just done the outside before with decent results. Has anyone tried this before and if so how did it sound? I also don't want to kill the tone of the pickup.

[guitician]

Blocking EMI/RFI noise and hum will require total coverage. Like a base plate with a nickel cover. And yes, it will sound different. There are all kinds of noiseless "Strat" pickups, why bother trying to partially shield? If your playing this into a sensitive input you'll want humbucking "single coil" types, or the backplate.

[voodoochild]

I have conductive adhesive shielding tape. I was thinking of wrapping around the coil and connecting another piece from that to the underside of the pickup across all 6 magnets. That should do the trick no? I know it changes the sound but I want to be able to reverse this if he doesn't like it. If I wrap the inside with copper and wind over it I'm screwed.

[Mike Sulzer]

The type of shielding that you are planning to do is good for shielding out electric fields. Humbuckers cancel out magnetic fields. You cannot make a single coil do that. (So-called noiseless single coil pickups are some kind of humbucking design that fits in a single coil slot.)

[Mark Hammer]

Dummy coils can be your friend, but a lot of folks have unrealistic expectations about them, and occasionally counterproductive mindsets about what a dummy coil has to be.

The advantage of the Suhr system is that the hum-rejection is decent without incurring a tonal penalty. Does hum-rejection need to be "perfect"? Nah. I imagine most players of traditional SC-equipped guitars would be happy (though not necessarily satisfied) with 6db reduction in hum. So, if you can try a few experiments in whipping up your own ersatz Suhr coil on either the backplate or pickguard, why not? It won't be as good as the Suhr coil, but hey 6db less hum is 6db less hum, right?

[voodoochild]

The type of shielding that you are planning to do is good for shielding out electric fields. Humbuckers cancel out magnetic fields. You cannot make a single coil do that. (So-called noiseless single coil pickups are some kind of humbucking design that fits in a single coil slot.)

I know it isn't humbucking. I need to try and cut the noise down as much as possible on the single coils. I completely shield my guitars anyway but I don't shield the pickups. This is more of a customer request than anything else.

[Sir Cuitous]

No matter what you do with shielding single coils and the cavities of the instrument, you still have the poles of the pick-up just hanging out there like antennas picking up more than just the string vibrating - ahhh but the tone.......

[David King]

I've had very good luck with the nickel spray paint on the top and back of the PU as it grounds all the magnets at once. I just wrap a piece of copper tape around the coil and insulate the ends so they don't form a loop. Ideally you'd avoid loops through the magnets and only connect them to the top or the back. Just look out for shorts to the magnets on your inside coil connection.

[Arthur Dent]

Low-impedance!

[David Schwab]

Low-impedance!

Low impedance single coils also hum.

[StarryNight]

I thought this might help. Seems like a pretty easy design. I wonder how strict/specific the patent is on it.

[David Schwab]

I thought this might help. Seems like a pretty easy design. I wonder how strict/specific the patent is on it.

The patent is for a "...large free shaped low impedance coil for noise cancelation"

The actual invention was intended as a coil embedded in the body around the pickups, but the trem cover coil falls within the invention. The coil is shown round, square or freeform.

It says the closer to circular the coil is, the better, and it must be at least 5 times the "average square surface area of a regular single coil style signal picking coil". The dummy coil is said to be "100 to 1000 turns wound with wire gauge #41 or heavier." It goes on that the preferred coil has an overall diameter of 8" and be wound with 200 turns of 36AWH wire.

There is more to it than just a coil though, it also has some accompanying passive circuitry.

This is listed as a "simplified schematic."

[voodoochild]

Ok. I just tried shielding the single coils and let me tell you they sounded TERRIBLE! It cut back on the hum a lot, but it sucked the life/tone right out of the pickup. It was as if the low mids were knocked right out which is the best part IMO. I told my customer and he wanted to hear them anyway and agreed they didn't sound as good as the unshielded ones. Once took the shielding off, it opened them right up and they sounded fine. So lesson learned shielding single coils ain't for me. So I think he is going to save a few pennies and go with the Suhr backplate down the road which I think is the only design that makes sense for single coils without altering the sound.

[Mike Sulzer]

Did you remember not to complete the loop around the coil? You do not want a complete path forth the current to flow around.

Ok. I just tried shielding the single coils and let me tell you they sounded TERRIBLE! It cut back on the hum a lot, but it sucked the life/tone right out of the pickup. It was as if the low mids were knocked right out which is the best part IMO. I told my customer and he wanted to hear them anyway and agreed they didn't sound as good as the unshielded ones. Once took the shielding off, it opened them right up and they sounded fine. So lesson learned shielding single coils ain't for me. So I think he is going to save a few pennies and go with the Suhr backplate down the road which I think is the only design that makes sense for single coils without altering the sound.

[voodoochild]

Did you remember not to complete the loop around the coil? You do not want a complete path forth the current to flow around.

I'm not sure I follow you. I wrapped the coil with paper tape and then I wrapped copper foil around that and soldered it to ground. Are you saying I should leave a gap or a break in the copper somewhere around the coil? If so wouldn't that defeat the purpose of shielding it? I'm a newbe when it comes to shielding pickups themselves but I have been shielding guitars for 20 years. It sounds like there is a different method for pickups?