By Ed Malaker
Posted 03/07/2019
This is the first in a series of articles in which we will discuss every aspect of the guitar pickup. We’ll cover, with as much detail as possible, how pickups work, the different types, and when to use each. So, let’s get started.
Electric Guitar Pickups
A guitar pickup is a very simple electronic component known as a transducer. A transducer is a device that converts physical changes into an electrical charge. We use two types of transducers in our guitars. The first type changes the vibrations of our strings into an electrical charge, and the second type converts the changes in air pressure into an electrical charge. We will take a look at both types in this article on how pickups work, and talk about how and why each type is used.
Passive Pickups
The passive pickup requires no power to work, and it is by far the most common and most popular type. The first guitar pickup was invented by George Beauchamp (one of the founders of Rickenbacker guitars), who started working on ways to amplify his guitar in the 1920s. He tried several designs, including a washing machine motor and a sewing machine motor before coming up with a single-coil pickup.
From here the story of how pickups work is long and fascinating and features many legendary names, but the main takeaway is that the pickup places the guitar strings and a wire coil inside the magnet’s magnetic field. When a player plucks a string, it disturbs the magnetic field, and this, in turn, creates a very tiny voltage in the wire coil that is sent to an amplifier, to produce sound. The larger the coil is, and the stronger the magnet, the more electrical output the pickup can produce.
There are several varieties of the passive pickup, including the single coil, the P90, and the humbucker, which itself has several varieties, including the side-by-side humbucker, the stacked humbucker, and the mini humbucker. In each case, the pickup will work exactly the same way, and that is by using one or more wire coils in conjunction with one or more magnets in proximity to the guitar strings, to produce an electrical current.
Problems associated with this design are that it produces an inherent hum (because if it’s actually being a type of antenna), and that its strong magnets can pull on the strings and reduce sustain. This type of pickup is always used on inexpensive guitars and the craftsmanship quality often suffers, and can create more hum and/or poor guitar tone. It is very possible to build your own passive pickup with just a few parts, and for that reason, the rest of the articles in this series will be devoted to dissecting and understanding these pickups.
Active Pickups
The active pickup requires power, usually in the form of a 9-volt battery stored inside the guitar. This type is much less common than the passive style, in large part because it is much more expensive to build. This design uses the same basic design as a passive pickup and creates the sound in the same way, but with weaker magnets and much fewer windings around the coil.
This approach produces a much lower output than passive pickups and therefore requires that the signal gets boosted by a built-in preamp. The boosted signal is often much more powerful than passive pickups, however, and the result is that most people find that active pickups are louder than passive ones. This increased gain helps these pickups drive the amplifier harder causing it to more easily “break up.” This allows a player to get more distortion than with passive pickups, making this type very popular among Metal and Hard Rock players.
This design also offers the guitarist many other features not seen on a passive style guitar. It usually features adjustable Gain, on-board EQ, and far less noise than its passive counterparts. The smaller magnets will also reduce string pull, which can lead to increased Sustain. Some of the downfalls inherent to this design include a constant concern about battery strength, the pickup’s relationship to the quality of the preamp, and the fact that it’s simply more expensive to build and install.
Acoustic Guitar Pickups
While passive style pickups do exist for the acoustic guitar, they are often not the preferred choice. The acoustic guitar has a very airy and open sound that is hard to capture with a wire coil. For that reason, one of the following types of pickups is often used.
Miniature Microphone Pickups
This type of pickup uses a tiny microphone placed inside the body of the acoustic guitar, to pick up the sound. This type of microphone can be either a miniature condenser mic, which is not unlike the microphone in your cell phone, or it can be a pressure zone type of microphone, which is a special type of condenser microphone designed to pick up the sound from surfaces. These types of pickups are more like traditional microphones than pickups and they transduce air instead of the string vibrations.
Piezo Pickups
This is a more modern style of pickup, using crystals, or more commonly, certain types of ceramics, to physically pick up vibrations from the body of the guitar and transduce them into an electrical signal. This is the type of pickup most often used in silent guitars, and it is slowly replacing miniature microphones as the microphone of choice in acoustic guitars. Because this type of pickup really brings out the acoustic properties of an instrument it can even be attached to an electric guitar in order to make an electric guitar sound like an acoustic guitar.
Lightwave Optical Pickups
This is another type of pickup that is currently emerging. It uses infrared light to sense the vibrations of the strings and to transduce that into an electrical signal. This type of pickup reproduces a nearly perfect frequency response and is not affected by outside interference. This type of technology is likely to be too expensive at the moment, but it will likely become more mainstream in the near future.
Summary
As you can see, there are many different types of pickups, and each one has hundreds of manufacturers that make dozens of models. In learning about how pickups work, you’ll find that it can be a long, but fun and enlightening journey to find your favorite. In this series, we will go over all of the different types of passive pickups and help you get a true understanding of how they work and what makes them sound the way they do. You will even be able to build your own!
See you in the next article.