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I have a Squire Strat that I've been fiddling with off and on for a while. My coil selector has two positions of particular interest: neck+middle, middle+bridge. Now, if I use any one of the three coils I definitely hear both the clarity and the noise that comes through - but on these it seems to cut almost all of the noise out. The tone sounds a little different, but I can't quite put a finger on how to describe it - except perhaps a very gentle lowpass filter on the extreme end.

Am I just lucky, or is this "double-coil" selection basically doing what a humbucker coil does? Would I really get anything more with a humbucker vs what I already have?

One final sub-question - is there any way to deal with EM noise in my very local vicinity (eg, my computer) while only using a single coil?

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You're not lucky---well, you might be lucky in many other ways :), but just not in this particular way. The noise reduction you experience is intentional.

Here's the basic idea: The coils in your pickups "pick up" noise in addition to the vibration of the strings. Everyone's pickups do. When you have two pickups selected at once, the signal you hear is the sum of the signals from both pickups. If the pickups are wound in opposite directions and with opposite polarity, then when their signals are combined, the noise they picked up will be 180o out of phase with each other and will therefore cancel each other out. It's exactly analogous to the idea that 1 + (-1) = 0.

The unique sound you hear from having the two pickups selected is also due to phase cancelation. Suppose you have the neck + middle pickups selected. The middle pickup, because it's closer to the bridge, will pick up slightly more upper harmonic overtones than the neck pickup. In other words, the signals coming from each pickup aren't exactly the same (which accounts for why they sound different when you select one at a time). So when combined, some of the overtones from the two pickups will be 180o out of phase and again, these will cancel each other out. This is what accounts for the "gentle lowpass filter" effect you describe.

A humbucker has two coils, reverse wound with reverse polarity, and so the combined signals of the two coils cancels out the noise just like with the neck + middle and middle + bridge selections you describe. But because the two coils in a humbucker are right next to each other, their individual signals are much closer to each other than in your guitar. The two signals from the coils in the humbucker aren't exactly the same, so the combined signal still has the phase cancelation effect. But because the two signals are so close, the frequencies cancelled tend to be very high.

Long story short: You won't get more noise cancelation from a humbucker than you currently get from your neck + middle and middle + bridge selections. In fact, if you replaced, say, your bridge pickup with a humbucker, you'd actually lose the cancelation effect from your middle + bridge selection.

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  • Dead on. Great answer.
    – Jduv
    Apr 29, 2011 at 13:42
  • humbuckers tend to a more gravelly sound, which is definitely not the case with the Strat S-S-S style n+m and m+b selector stops.
    – horatio
    Apr 29, 2011 at 14:39
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It will depend on the wiring - some Strats have the middle pickup wired with opposite polarity to the neck and bridge ones. That way, when you select the combination of neck+middle or bridge+middle, you get phase cancellation which reduces the noise (much as a humbucker pickup does).

However, each pickup selected by itself still acts as a normal single coil, and thus you still get the typical hum.

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As the other guys before my stated, two single coils have a humbucking effect. But you should be aware of the fact that putting a humbucker in your guitar won't have the exact same result. (Except the "humbucking"-effect)

because, the coils of a humbucker are wired in series like this:

enter image description here

which delivers more punch, warmth and output.

But switching 2 Single-coils together, like in your case, are wired parallel like this:

enter image description here

which delivers bright and clear sounds.

Like I said, the humbucking effect would be the same, but the tonal qualities are different. So, in the end, it's a matter of taste actually.

In my opinion, 2 Singlecoils are a great combination for clean passages in songs. And a Humbucker (especially in the bridge) is great for Rock and Metal Rythm and Solo playing. (My personal tip for bright, clean AND warm clean-sound: Bridge-Singlecoil + Neck-Humbucker)

I hope, this helped you out a bit. :D

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  • In a humbucker, the north-pole magnets are close enough to the south pole magnets that I would expect their proximity to have a significant effect even if one only used one coil. Further, I would expect that if a single-coil pickup's magnet assembly installed in one of the coils of a humbucker, the other coil would pick up a signal about half as strong as the first, and in proper phase for humbucking operation. I don't have easily-separable pickups at my disposal, but my understanding of the physics is that flux which goes through a coil has to have a return path outside it.
    – supercat
    May 30, 2015 at 21:20
  • In a humbucker, the second set of magnets will cause most of the flux to return on the second-magnet-set side, but even without those magnets almost half would return through the second coil (about half would return on the other side of the main coil, and a little would return beyond the second coil).
    – supercat
    May 30, 2015 at 21:22
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Regarding EM noise: you could make a Faraday cage and set it over your computer case ( see: http://en.wikipedia.org/wiki/Faraday_cage ), but this will probably kill the computer's wireless reception (if any).

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  • 1
    In fact, making a Faraday cage, or "shielding" the electronics has long been standard practice on many bass guitars. You can either paint the interior of the guitar with conductive paint or line it with copper foil, and then wire it to ground.
    – Alex Basson
    Apr 29, 2011 at 18:58
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With regard to electromagnetic interference with your pickups, this is a big problem from a CRT (cathode-ray-tube) computer monitor or a CRT television. LCD and plasma screens do not produce huge amounts of EM noise. Certain kinds of lighting (flourescent, halogen) will also produce EM noise.

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To reduce noise from single coil you have several options:

  • Step away from interference source or turn it off if possible
  • Fix the guitar shielding if it is wrong
  • Buy noiseless single coils
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