Ready For Pickup : Understanding and Appreciating Your Guitar’s Passive Pickups
Lane Sparber
Hello, EarthQuaker gang! Today I’d like to tackle the basics of a vital ingredient in your tone: the passive guitar pickup. There are a lot of factors that go into a pickup’s construction and subsequent wiring, and I’ll touch on some of them briefly here. My hope is that those of you considering swapping your pickups (or those of you who want a deeper understanding of what’s going on under the hood of your guitar or bass) will have a more informed frame of reference from here on out.
PICKUP LINES
A passive guitar pickup is a pretty basic device. In essence, it’s a coil of wire around a magnet. Which, in totality, is also known as an “electromagnet.” This electromagnet sets up an invisible magnetic field around your strings. When the strings are strummed or plucked, they disturb this magnetic field. This disturbance is then sensed by the pickup and converted to an extremely small electrical current. This current is then sent to your amp.
Most passive pickups consist of three simple components: the aforementioned coil of wire, the magnet (or magnets), and the bobbin that the coil is wound around. Each of these factors can make a big difference in the pickup’s tone. In fact, the variances here are almost solely responsible for the overwhelming choices out there when it comes to the HUGE variety out there in modern pickups and their tones. Let’s take a closer look at these factors.
TIGHTLY COILED
The coil itself is extremely important. The diameter of the wire used is extremely thin - often thinner than a human hair. There is also a wide variety of different diameters and insulation materials used to create these wires, and all of this can affect your tone in different ways. The thinner the wire, the more times it can be wound around the coil - leading to a “hotter” output pickup. There are also two basic ways that the pickup can be wound: machine wound (totally symmetrical) and “scatterwound (hand-wound).” What are the differences? Well, that’s up for debate, because by definition, hand wound pickups aren’t all the same. In essence, a hand-wound pickup’s windings aren’t completely adjacent to each other, and thus they have more open space in the coil. This CAN lower the coil’s distributed capacitance. That’s just a fancy way of saying that the pickup tends to be a bit brighter when wound this way, and since there’s more space in the coil, there tends to be fewer windings, leading to less current generated. This all CAN add up to a brighter, more “hi-fi” sound.
MAGNET SCHOOLS
The magnet positioning and material also has an enormous effect on how your pickup sounds. When it comes to magnet material in pickups, there are two basic options: ceramic or AlNiCo (an alloy of aluminum, nickel, and cobalt). Even within these two magnet types, there are a lot of variance, and (to make matters more confusing) some pickups even combine both materials at once.
It’s hard to give general labels to how these magnet types affect tone, but in essence AlNiCo tends to sound warmer and have a more “vintage” tone. There are several different formulas (strengths) for AlNiCo (usually labeled by number, such as “AlNiCo 2, 3” etc.), and they all sound different. Vintage Strat and Tele pickups use AlNiCo magnets, by way of example. Ceramic magnets, on the other hand, tend to emphasize midrange and they’re also far more powerful, by nature than AlNiCo. This is why a lot of pickups geared towards the hard rock and metal communities utilize ceramic magnets. By way of example here, the venerated and legendary DiMarzio “Super Distortion” uses a ceramic magnet for that gut-punching, in-your-face tone that they’re famous for.
It’s also worth pointing out that the magnet placement itself also varies from pickup to pickup. In single coils, the pole pieces themselves are often the magnets (if they’re AlNiCo):
If your single coil happens to have a ceramic magnet, you’ll usually find an oblong bar magnet glued to the underside of the pickup itself, and this “energizes” the pole pieces from there:
In most humbuckers, the magnet lies UNDERNEATH the bobbins, and the pole pieces get their magnetic orientation from it.
Note that these bar magnets here have two sides, which makes one coil “North” polarity and one coil “South” polarity, depending on the magnet’s orientation. These magnets can be physically flipped over to reverse the polarity if needed.
In this pic, I’m using my magnetic pickup polarity tester to determine which coil in this pickup is “North” and which one is “South.” It has a tiny magnet in it that rotates to show you the polarity of a pickup when held above the magnet. It’s a REALLY handy tool for working with guitar and bass electronics.
Finally, we come to the humble bobbin itself. The bobbin’s primary task is to provide mechanical support and a structural framework for the coil. It influences tone primarily in the way it does its job - bobbins can be tall and narrow (like a vintage Strat pickup), or they can be wide and shallow (like a Jazzmaster or P90 pickup). In my own experience, the bobbin’s material itself doesn’t matter that much, as it’s electrically inert (inactive), but there are endless debates on this all over the internet. Once again, to speak in generalities, the wider and flatter a coil is, the more it emphasizes low mids and lows and de-emphasizes treble. This is most likely why Leo Fender made those Jazzmaster pickups so wide and fat, as he was obviously targeting jazz musicians -who tend to prefer a warmer, fatter tone. It’s ironic, because I’ve never seen any actual jazz guitarists playing a Jazzmaster!
A Strat pickup bobbin (top) and a Jazzmaster pickup bobbin (bottom). Note the vast difference in the shapes of the coils that can be wound around them. This accounts for a large part of their massive differences in tone.
PHASED AND CONFUSED
Now we move on to a pickup’s phasing, and how it relates to the pickup’s polarity.
To review in brief, a pickup’s polarity refers to its magnetic orientation. It can be either north or south, and this parameter is set by the orientation of...you guessed it...the pickup’s magnet(s). This, as we’ve learned, is changeable, as you can swap a pickup’s polarity by either flipping the magnet (if it has a bar style magnet like humbuckers and ceramic single coils) or re-magnetizing them (if the pole pieces themselves are the magnets, like in a typical vintage style Strat pickup).
Phasing in a pickup refers to the direction that the electrons flow through the pickup. In almost all passive guitar and bass circuits, one end of a pickup’s coil is connected to ground, and the other end (the “hot” lead) goes to the pickup selector, a volume pot, or another pickup…and then on to your amp. Even though a pickup’s coil has a physical start (inside) end and a finish (outside) end, the polarity can still be reversed simply by swapping its wires, which reverses the directional flow of the electrons through it. This simple wire swap will work regardless of the physical orientation of the coil’s inner or outer leads.
In concluding the section on polarity and phasing, I’d like to again point out that most pickups’ phasing and polarity can be reversed with a simple magnet flip (or re-magnetizing it) and reversing the wires. This is especially handy, for example, when you want to change the phasing and polarity of a Strat’s middle pickup so that it’s hum canceling in switch positions two and four. Which brings us to...
HUMBUCKING THE TREND
What is a humbucker exactly? In the simplest terms, a humbucker consists of any two pickups of opposing phase and polarity. These two pickups can be wired together in series (one after the other) or parallel (both hots and grounds are wired together). When these coils are out of phase and out of polarity with each other, their hums are knocked out by phase cancellation. Phase cancellation is where two signals of opposite phasing interact with each other. When this happens, certain common frequencies can be boosted or cut. It just so happens that the 60-cycle hum is one of the frequencies that is cut by this phenomenon, and at the same time the mids tend to get a big boost. This said, pickup designers can custom tailor the phase cancellation (and other parameters) in ways that are pretty much indefinite, leading to endless varieties of tone and flavor, so that’s a major win for us!
Keep in mind that the two pickups in a humbucker do not need to be under the same cover, or even close to each other. Most modern Telecaster middle positions and the number two and four selector positions on a Strat are humbucking, even though the pickups are far apart from each other. As long as one of the pickups in play is reverse wound and reverse polarity (rwrp) and the coils are wired in series or parallel, you’ll essentially have a single humbucking pickup.
FEELING WIRED
When it comes to buying pickups for your guitar, there are two basic types of wiring configurations out there. All single coils and some humbuckers use two-conductor cable (or two single wires, like a Strat pickup). Some humbuckers use 4-conductor wiring. So what does it all mean?
Two-conductor pickups utilize the most basic wiring scheme out there. In single coils, each end of the coil is connected to one of the wires. That’s it. Additionally, if a single coil has a third wire, it’s usually a ground wire connected to its cover (like a Tele neck pickup) or its bottom plate (like a Tele bridge pickup). By separating the grounds like that, it enables the end user to control the pickup’s phasing with other pickups. Most often though, those covers and baseplates are wired directly to the black wire coming out of the pickup for simplicity.
In two-conductor humbuckers, the pickup’s coils are hard wired together in a series (almost always) or parallel (rarely) configuration, and you can’t change it or do any fancy wiring unless you break into the pickup and change it (NOT recommended). You get a humbucking pickup and that’s ALL it will do.
Four-conductor humbuckers bring the starts and finishes of both coils outside the pickup for a nearly endless array of custom wiring options. There’s often a bare wire in the cable too that’s connected to the pickup’s base plate for grounding (so it’s technically a five-conductor arrangement). Having a 4-conductor humbucker enables you to control the pickup’s phasing, coil-tap it (short out one coil for true single coil tone…although it rarely sounds just like a TRUE single coil, but close enough for most ears), or wire its two coils in series AND/OR parallel configurations. Being a control freak who loves options on all of my guitars, I almost ALWAYS use four conductor pickups.
TIME TO UNWIND
In wrapping up (heh, heh) this discussion of the basics of passive pickup design, construction, and wiring, I’d just like to add that I hope you’ve found this info to be instructive, entertaining, and informative. The science here isn’t too hard (compared to, say, amp design), and experimenting with pickups is one of the most enjoyable and potentially rewarding tone-chasing activities you can engage in. I hope that now you can make more informed decisions about what may or may not be right for you in a new pickup…and how it should be wired to suit your tone needs.
Happy hunting!!!
Lane Sparber is an amp / guitar / bass / pedal tech who lives and works in Fresh Meadows, Queens, New York. He started repairing gear in his mid-teens, and he’s 46 now, so you do the math. When not causing mayhem in his workshop, he can be found desperately trying to hide his latest orchid purchases from the rest of his family. You can find him on Instagram at @amptech74 or on Facebook. Come say “Hello!”
