S.H.I.E.L.D.ing a guitar

or, Strategic Harmony Interference Elimination and Lead Defense.

Guitar pickups are electro-magnetic transducers that use changing magnetic fields to induce pulses of alternating current electricity from a coil of copper wire at voltages reproducing audible sine wave frequencies in relation to an absolute ground. I think. Sometimes I prefer the definition as proposed by Messrs. Dope and J; magnets are a “miracle.” Unfortunately, the latter definition does nothing to help understand why my bass might be buzzing like a bee chainsawing an alarm clock when the FOH sound guy turns the lights on and off. There’s two ways to solve the problem. One, you can learn to play the chainsaw.

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it works for that dude in Exhumed

Or two, you can shield your guitar. Truth be told, it should probably be shielded from you: throwing it around, spilling beer on it, bleeding on it… and by “you” I mean “me.” But the shielding I refer to will protect that precious guitar signal of malodorous melodies from the buzzing bullshit of the outside world.

“But it’s a grounding issue,” you say. And I say, “Are you sure?” And you say, “Fuck you, Ross, you better not tell anyone about this.” I reply, “I would never think to betray your trust that way, Mr. President.”

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Touch the strings. Does the guitar buzz more or less? If it buzzes more, oh verily, there is a grounding issue and something is touching something it shouldn’t, as if your guitar cavity was Neverland Ranch. If it buzzes less, or more likely, not at all, then your guitar wiring is fine and you need to shield it.

See, you are a capacitor. The human body can not only conduct electricity, it can also store it. Think about the time you zip across a carpet and shock someone. ZAP! That potential energy affects the pickups. You’re also an antennae. All that bullshit electricity zipping through the air? It’s looking for you and will project when it finds someplace better to go, like some wound up copper wire. That’s why when you get close to a guitar pick up, it starts buzzing more.

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scientific diagram of the human body as a capacitor

But when you touch the strings and the buzzing goes away… MAGIC! No, not magic. It’s just all your stored bullshit zips down into the ground (if your guitar is properly wired) right through your amp and NOT through the pickup signal. You become a gigantic wall of zero potential energy that everything siphons through. That’s why your guitar stops buzzing when you touch your strings, because you’re now part of the path to ground.

So grounded
So grounded

Sometimes, though, you are not shield enough. Or maybe you want your guitar to not buzz even when you’re not touching it. That’s when you introduce the idea of a Faraday Cage. That’s basically a zero sum shield around something that diverts all extraneous electronic signals to ground and away from what you’re trying to protect. With a Tesla coil, you’re trying to protect the halfwit that’s willing to stand near an object that’s projecting 1.21 giggawatts.

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Photo courtesy a halfwit

With your guitar, you’re trying to protect the copper coil reading the nearby magnet and oscillating steel or nickel string that creates the signal sent to your amp. Setting up a mini Faraday Cage in your guitar body blocks out (or rather, absorbs) the extraneous bullshit, like playing Candy Crush on an iPhone does for you when you’re with in-laws watching Fox News.

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That is a Fender P bass, with two pickup slots and control slot that I shielded for Mark Reategui from Deadfall. The shielding is copper tape, available online or through a ma and pa electronics store smelling of mothballs and cat piss in a neighborhood near you. All this shielding has to be connected to ground, of course, otherwise, it’s not shielding at all; rather, it’s an antennae for noise.

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Even the pick up cover can be shielded. The copper tape needs to be folded over so that when the pick up is inserted, it makes contact with the conducting material inside the cavity. Wait, there’s more?

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Fuckin A, right. Even the magnets can be shielded, as they’re coated with material that also will conduct unwanted interference to ground. And that’s the tricky part… making sure it all goes to ground. One way to do that is to line all the cavities carrying wires with some braided metal sleeving.

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You can thread all leads through braided metal sleeves and solder it to all the copper taping that’s shielding pickups, control cavities, etc. Now, even your leads are in an extended isolation chamber. Just make sure that all connects to the ground of the jack, and you’re set.

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On my own B.C. Rich Warlock, the control cavity and cover are also covered in copper tape. Everything is shielded and now my bass is dead silent until I hit the strings. I also upgraded to  Bournes Vintage Pots which have a smooth turn to them and are sealed from dust. A bit pricier than some potentiometers, but they last a lot longer, too.

Get to shielding those guitars. The more it’s shielded, the more it’s protected against noise from things like fluorescent lighting, dimmer switches, P.A. amps, high-voltage wires, stage lighting, computer monitors, etc. If only I could shield it from the awful noise created by me playing it. To dream…

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