Hum, Polarity, and Phase in Guitar Pickups

[Sam Sherry]

Chris --

Your original post is certainly clear. I'd like to take a whack at "even shorter."

. The coils in guitar pickups are antennas. That means that a single-coil pickup makes purposeful noises -- notes -- and also make accidental noises -- hum picked up from ambient sources.

. Two coils wired with reverse polarity result in cancellation of the antenna effect. "Reverse polarity" means the inside lead of the coil is hot on one coil, and the outside lead of the coil is hot on the other.

. If the coils are reverse polarity, and the magnetic North/South polarity is also reversed, the musical signal comes from both coils in the same direction ("in phase") AND the antenna/hum signal is still canceled.

. That is true whether the coils are wired end-to-end -- series, for more output -- or side-by-side -- parallel, for less output and a mid-range spike.

[PTChristopher2]

Hi Sam,

In my opinion shorter is implicitly better, so your summary strikes me as an improvement.

I suggest one minor addition regarding the coil.

>>> "Reverse polarity" means the inside lead of the coil is hot on one coil, and the outside lead of the coil is hot on the other.

This is certainly true, but in many cases, the coil reversal is done by actually winding one of the coils in the opposite direction vs. the other rather than swapping the hot and ground ends on one of two similarly wound coils. So I suppose both methods would be good to mention.

*******************

With all the absurd myth surrounding guitar sound (oil/paper caps, polarity and "tone", etc.), I am surprised that luthio-quackery and associated minions do not make a big deal over which end (inside vs. outside) of the coil is "hot".

Chris

[PTChristopher2]

And when will "side-wound" HB pickups come up? I remember some seemingly impossible combination of harsh and dull sounding Strat PUs made this way decades back. Maybe it was Bill Lawrence, but I do not recall.

The side-wound configuration being, in effect, a P100 on its side - which REALLY takes away any excuse I could claim for my first post on the P100 being so screwed up.

Chris

[D.G.]

The Fralin noiseless P-90's are side-winders.

[PTChristopher2]

Hi DG,

Thanks, I had no idea how they were made.

I have made several attempts at effective dummy coils, but in my opinion they really shine when the PU and dummy are separately buffered then combined.

So while the P-100 is not a dummy coil design, the vertical stack would give some of the same troubles I had in trying to get a dummy coil to have a semi-dummy effect by getting it partly in the effective magnetic field of the main coil.

I can see why one might try a side-wound solution for the P90 sound.

I have never really fooled with side-wound PU's, but I do not exactly see how you would end up with a P90 style sampling along the string length. Do you have a set of these PUs? Can you see if the coils are shielded with a metal foil, with the pole pieces (screws) thus extending out of the shielded cage in the center?

Just curious.

Chris