In order to understand what we are talking about when we say single coil and double coil, we’ll first take a look at the different parts of a pickup and see how they work together to produce a guitar signal. Then we’ll examine single coil and double coil pickups, the differences between them, and why you would want to use each type. We’ll discuss the single coil first because it’s the original type and it has a simpler design. We’ll start with the parts, then move into the ways the single coil and double coil pickups actually work.
In a single coil pickup (double as well), there is what’s called a bobbin. The bobbin is usually made out of plastic or fiberboard, but it can be made from cardboard, wood, or anything non-conducting. Oftentimes, the bobbin is made from a non-conducting top and bottom, held together by six magnetic posts, or machine screws, with a bar magnet on the bottom, but bobbins can come in all shapes and sizes. The main purpose of the bobbin is to provide a structure to wrap the copper wire coil around, and to provide housing for the magnets, steel posts, attachment screws, etc.
Magnets are essential to bobbins, and there are several types, each having specific qualities. We go over each type of magnet and the effect it has on tone, in our Build Your Own Pickups article, but in this one, we’ll just discuss the two most common types: ceramic bar magnets and alnico post magnets.
Ceramic magnets are strong, permanent, and made mostly from iron rust in the form of iron oxide. The iron oxide is mixed with nickel, zinc and/or a few other elements, and baked at high heat to produce the ceramic magnet. This type of magnet does not conduct electricity, it’s cheap to build, and it usually leads to a bright-sounding pickup with high output. In the bobbin, the ceramic magnet is usually a bar that lays at the base of six machine screw posts that are spaced to match the strings. Because the brightness of the ceramic pickups can lead to a sound that is harsh and brittle, guitar players sometimes dismiss them altogether. Many great-sounding ceramic pickups have been produced, however, and they’re worth checking out, including the Seymour Duncan SH-6 Mayhem.
Alnico magnets, also strong and permanent, are made from melting together and casting aluminum, nickel, cobalt, (al-ni-co), and iron. Alnico magnets conduct electricity and they are usually more expensive than ceramic magnets. The properties of alnico magnets tend to give pickups a warmer, more organic sound than ceramic pickups, but often at the price of a lower gain output. In the bobbin, six alnico magnets shaped like posts are used instead of the machine screws, and no bottom bar magnet is needed. Alnicos are often the go-to magnets for higher-end pickups, and several great-sounding ones have been produced using them, including the Gibson ’57 Classic.
The direction of the magnet, North Up or South Up, is called the pickup’s “polarity” and it’s a crucial part of how pickups work together.
A very thin, (usually) copper wire is wrapped around the bobbin thousands of times to create a coil. The beginning of the coil is soldered to the (usually) black wire, and becomes the “Negative” or “Ground.” The end of the coil wire is soldered to the (usually) white wire, and is considered the “Positive” or “Hot.” If the pickup is wound clockwise, it is considered “Standard Wound;” if it’s wound counter-clockwise it is “Reverse Wound.”
The direction of the coil winding is called the pickup’s “phase” and is a crucial part of how pickups work together.
How Pickups Work
The magnets in the bobbin create a magnetic field (or multiple magnetic fields). The copper coil and steel guitar strings are placed inside that magnetic field. When a guitar player plucks a string, the vibrations of the steel cause the magnetic field to vibrate at the same frequency. The vibrations in the magnetic field cause a reaction in the copper coil and they are then translated into small voltage changes in the copper coil. Those voltage changes travel through your guitar cable to your amplifier and they get amplified to a point that can drive a speaker, allowing you to hear your guitar sound.
The magnets and their polarity, the number of turns in the coil, and the direction in which they are wound, affect the small voltage changes that are sent to your amplifier.
The Single Coil Pickup
Single Coil pickups are known for a bright and crisp tone that leads to very defined notes that can cut through a loud environment. They are the original, and still the favorite of many guitar players today. The best example of a single coil design is probably the Fender Stratocaster, which uses three single coil pickups. It’s a legendary instrument, well known for its extremely versatile tone.
The main downfall with the single coil pickup is that it creates a very noisy hum. But it was discovered early on, that if you pair one single coil pickup with North-facing magnets and Standard Winding with another single coil pickup with South-facing magnets and Reverse Winding, the noisy hum will be eliminated. It works on the same principle as balanced microphone cables. Other examples are noise-canceling headphones and microphones that use two out-of-phase signals and combine them to eliminate interference. You can still see this idea in practice on many guitars, including a Fender Stratocaster.
The Strat has three single coil pickups, and the polarity and winding of the middle pickup is the reverse of the other two pickups. This gives the Fender Strat a noise-free sound on positions two and four of the five-way switch. On position two you use the neck pickup and the reversed middle pickup. On position four you use the bridge pickup and the reversed middle pickup. If you were to switch one of the pickups to a third-party model, you would need to make sure that the direction of the magnet and the coil winding are correct.
The Double Coil (Humbucker) Pickup
Once this coil arrangement idea took hold, the next logical step was to combine the regular coil and the reversed coil into one noise-canceling pickup, and this double coil design became known as the humbucker. The idea is that when you select a humbucker pickup, you get a hum-free operation with no need to worry about winding or polarity. You can see this idea today by checking out a Gibson Les Paul. The Les Paul has two humbuckers and a three-way switch. Each position on the switch (neck, neck + bridge, bridge) delivers a hum-free signal. You can, therefore, switch to third party pickups without having to worry about polarity or winding.
So, now you might find yourself asking why you would want to use noisy single coil pickups when noise-free humbuckers exist. The answer is that single coil pickups still have a lot to offer a guitar player, even if they are noisy. Single coil pickups tend to sound brighter and have a clearer, more defined tone, with a lot of “bite,” that many guitarists prefer, and that Country players depend on. Humbuckers tend to have a warmer and smoother sound that many describe as sounding “fat.”
Single Coil and Double Coil Pickups
You’re going to find both single coil and double coil pickups in every style of music, and each type has legions of followers who swear it is the best and only one to use. You’ll find single coils in a lot of Jazz, Country, and Classic Rock types of music. In other words, music in which the guitar player tends to use a little less gain, needs twang, and/or plays with a lot of clean tones, with fast and complex musical passages. You will find a lot of humbuckers in high gain styles of music such as Hard Rock and Metal, where distorted amps really magnify that single coil hum. The humbucker’s two-coil design also has a higher output that is perfect for these styles of music, where you want to drive the amps harder to get more distortion. They are also great for slower types of guitar solos, where you want a warm tone with lots of sustain.
Remember, the magnets, the number of windings, the wire gauge, etc. all play a very important part in the sound of the pickup, even in humbuckers. This means that there are a lot of very different-sounding single coil and double coil pickups out there, and the only way to determine which is best for you, is to try them out and use your own ears to decide.