Fig. 1 — Photo by Dan Formosa

You learned everything you need to know about guitar pickups in your 5th grade science class. Or at least 90 percent of what you need to know. Reflecting knowledge dating back a hundred years, a pickup’s electromagnetic principles are rudimentary and covered in every grade-school science book. However, the other 10 percent—how to implement those principles and apply them to an electric guitar to make you sound like the musical god or goddess you are—is what legends are made of. Let’s review the first 90 percent; we’ll stick close to the basics and explain how electromagnetic pickups work, in case you were absent from class that day.

To start, pickups are based on two separate but related principles: If you place a coil of wire near a magnet and induce a change in the magnetic field, electricity will be generated in the coil’s windings. Also, if you place a piece of non-magnetized ferrous metal near a magnet—a screw, nail, a paper clip, whatever—it too will become magnetic.

There’s a chronological sequence of where your guitar sound starts and finishes. The energy from your fingers and pick is transmitted to your guitar strings, which disturb the pickup’s magnetic field, thus affecting a coil of copper wire within the pickup and generating an AC signal that trails out from the two ends of the coil to connect to any tone and volume controls your guitar may have. From there the signal heads to your guitar’s output jack and instrument cable, through any pedals, and finally to your amp and speaker.

Every one of those stages will have a significant effect on the resulting tone. There is enough to discuss about this topic to fill a book—and in fact it has, many times. To begin to understand pickups, let’s look at those first few stages.

It All Starts With Strings
The first step in getting a pickup to generate any signal at all is to disturb the pickup’s magnetic field. Though electric guitar strings come in many varieties, they all share a common trait—the ability to affect a magnetic field as the string vibrates. Naturally, this means the strings need to be vibrating somewhere within that field. Depending on a pickup’s design, its magnetic field may span a small or wide area, and that’s good to keep in mind.

Because strings are responsible for a significant portion of an electric guitar’s sound, it makes little sense to compare the performance of different pickups until you’ve done your homework with strings. You’ll want to be familiar with the basics, which includes exploring the differences between lighter and heavier gauges, nickel-coated steel or pure nickel windings, roundwound or flatwound construction, and round or hex cores. Consider buying a handful of different types of strings made by different manufacturers and spending quality time with each set. There’s a reason manufacturers offer so many string choices, and a little experimentation can yield big dividends.

Why bother staggering the pole heights? It’s simple: Different string types and gauges will perform differently.

Tom Klukosky, whose “factory manager” title downplays his multi-functional role at DR Strings, points to three string-related variables that affect your sound: the string material, the winding technique used for the wound strings, and the string’s ability to vibrate. He points out that strings are the “singers,” the originators of your tone. If you don’t like the singer’s voice, changing the microphone isn’t going to help.

Strings disrupt the magnetic field by vibrating within it, and a string’s material affects the strength of this disruption. And with wound strings, this becomes a key consideration. Unlike nickel-plated steel, pure nickel doesn’t affect the magnetic field. Neither does stainless steel—the core is doing the work.

In choosing strings, don’t simply go by what you might hear others say. For instance, strings wound with pure nickel have a reputation for “warming up” your sound. However, Klukosky prefers them because the plain (unwound) strings sound brighter in comparison to those wound with pure nickel, and this shifts the overall tonal balance toward the treble strings.

Location, Location, Location
String vibration is greater in the area of the neck pickup and less towards the bridge. The difference in vibration along its length means that different pickup positions result in readily noticeable variations in tone. If you ever get a chance to tinker with an archtop equipped with a floating pickup that can be readily repositioned between the bridge and the neck—such as the classic DeArmond Rhythm Chief—you’ll see how sensitive the positioning can be. If your guitar has multiple pickups, their positions (neck, middle, or bridge) will be taken into account by their maker.

While two or more pickups might seem ideal in terms of tonal variety, these extra colors come at a cost. One advantage of a bridge-pickup-only guitar is the absence of magnetic pull on the strings that a neck pickup would exert. This pull can impede string vibration. It’s one reason why the single-pickup Fender Esquire, for example, has its fans. Mod Garage author Dirk Wacker put it nicely in PG’s April 2012 issue: “The Esquire is not a Telecaster with a missing neck pickup, but rather a distinct model with its own sound.”

You can also do very well with just a neck pickup. Equipped with only a neck pickup, my 1955 Gretsch Streamliner archtop gets a lot of use. The absence of a bridge pickup, which would otherwise add mass near the bridge, allows the top to react more freely around this critical area, and this gives the guitar a nice woody tone.

In evaluating pickups and related technology, just remember that a pickup is a sensor, and that the sound starts a few millimeters above it. Reinforcing that view, in the 1960s Gretsch referred to their pickups as “Electronic Guitar Heads,” borrowing the term “head” from tape recorders, which also rely on magnetic technology (Fig. 1).