Part 3: There are a couple of ways to classify magnetic guitar pickups. Let’s start with these two.
Single Coils vs. Humbuckers
As the name would suggest, a single coil pickup is a single coil of wire wrapped around a bobbin. Single coil pickups were the first pickups made. Early on, they were used on the Gibson ES-150 Charlie Christian model. Also, traditional P-90s are single coils. All of the first Fender pickups used on the Broadcaster/Nocaster/Telecaster, Stratocaster, Jazzmaster, Jaguar and Jazz Bass instruments were single coils. Some current jazz players who rely on single coil pickups for their tone include Julian Lage, Oz Noy, Nels Cline, Scott Henderson, and modern Instagram superstars Mateus Asato, Yvette Young, and Annie Wagstaff. Single coil pickups have a clear and bright tone; but they have one inherent weakness. In addition to picking up string vibrations, they’re susceptible to picking up a hum generated by the flow of electricity. Here in the States, we call it 60 cycle hum, but in other parts of the world, electricity flows at 50 cycles per second. Be that as it may, if you’ve ever plugged into a hot amp and even before you start playing, you hear an annoying hum coming out of the speaker, that could be 60 cycle hum. It could be other things too. Either way, it could elicit nasty looks from your singer and it’s something you definitely want to avoid in the studio.
In 1955, a design engineer working at Gibson by the name of Seth Lover, took some inspiration from an amplifier choke design, and figured out a way to wire two single coils, each with an opposite winding direction, and couple one to the north side of a magnet and the other to the south side, and wire them a specific way called in-series, out-of-phase. The result was cancellation of 60 cycle hum. This pickup that “bucked” the hum, as it were, was marketed as a humbucking or a humbucker. Nowadays, humbuckers are the most popular electric guitar pickups. For jazzers, the holy grail humbuckers are the ones made by Gibson in the late-50s, during the period when Gibson’s patent was applied for, but before it was granted. Those “patent applied for” or P.A.F. pickups are the same or very similar to the pickups used by vintage jazz stalwarts like Joe Pass, Kenny Burrell, George Benson, Herb Ellis, Tal Farlow, Barney Kessel, Jim Hall, Grant Green, and Wes Montgomery; and modern players like Pat Metheny, Johnny A, and John Scofield. Because they have two coils wired together, humbuckers, when wired in series, typically have a higher DC resistance than single coils, resulting in a fatter and warmer sound.
There’s a hybrid pickup design called single coil-sized humbucker. These pickups are direct replacements for typical Strat, Tele, and P-90-loaded guitars, but they use two coils to cancel the hum. Some use two coils side-by-side, like Joe Barden’s dual rail design, DiMarzio’s Fast Track series, or Nukleus, a new start-up out of Miami; and others use two coils, stacked one atop the other, like Seymour Duncan’s Stack design or DiMarzio’s Virtual Vintage range. Some of these designs, particularly for Strat, Tele and Jazz Bass, come really close to bucking the hum and preserving the tone of a real deal single coil. Others, like hum canceling P-90s, are—shall we say—still trying to crack the code.
Active vs. Passive
All the pickups we’ve talked about so far use just a coil and a magnet, along with vibrating guitar strings, to induce a current and create a guitar tone. We call these passive, or high impedance pickups.
Active, or low impedance pickups, also use a coil and a magnet, but in addition, they also employ a battery-powered preamp to boost or otherwise shape the frequency response of the pickup. They are almost always hum-canceling designs to begin with. They are often used by metal players and the most famous offerings are EMG’s 81 and 85 models, Seymour Duncan’s Blackouts series, and Fishman’s Fluence range. I’m sure there are lots of jazz players who use active pickups, but I can’t think of any.
There are numerous wiring options to consider when installing pickups that could result in new tonal options. Some single coils come with a reverse wound, reverse polarity (“RW/RP”) option. In a three-single coil pickup guitar, an RW/RP pickup in the middle position will cancel hum when it’s combined with either of the other two pickups. Other single coils are tapped, which means they have two outputs, one accessing the full number of windings and other accessing just a portion of the windings. Less windings equals lower DC resistance and a higher resonant peak—and it means more tonal options for you.
Speaking of tonal options, most passive humbucker pickups come with four-conductor hookup cable which offers four different wiring options and four different sounds. The standard method for installing a humbucker is in series, humbucking mode. But it can also be wired in parallel, humbucking mode for more of a single coil-like sound; or the coils can be split, so only one is working, the result being a true single coil sound, but losing hum-canceling unless combined with another RW/RP single coil; or out of phase, which is a thinner sound and is not hum-canceling.
The humbucker options and the tapped single coil tones can be accessed by switches that can be part of your guitar’s 5-way or 3-way switch, or via push-pull potentiometers, or by toggle switches, or even humbucker mounting rings with built-in slider switches.