Single coil pickups tend to have brighter, crisper tone. Humbuckers typically have what guitarists describe as a “thicker” sound; one that is perceived as rounder and warmer. Humbuckers also tend to emphasize the sustain produced by the guitar’s tonewoods.
Single-coils are often described as having more “bite” and attack than humbuckers. They can also sound “gritty” when overdriving small tube amplifiers. Depending on the type of amp, effects and playing techniques used, single-coils can also produce the glassy, chiming tones associated with classic ‘60s pop guitar.
While you’ll see all kinds of exceptions, single-coil pickups are generally preferred by country and surf guitarists who are going for maximum twang. Conversely, humbuckers tend to be more popular with jazz, heavy rock and metal players. With their emphasis in the midrange and a broader spectrum of distortion effects, humbuckers are also popular with blues players seeking overdriven tube sounds.
With all that said, it has become harder to make generalizations about pickup characteristics. New, hotter single-coils can compete with humbuckers output-wise. Groundbreaking ceramic and magnetic metal alloys in humbuckers are delivering the high-energy signals demanded by sonically intense genres such as thrash metal. Active pickups and electronics that contain their own preamps are another way to go for guitarists seeking the hottest possible signal to feed to their high-gain amps. The pairing of EMG 81/85 active pickups in the Zakk Wylde Set is a classic setup for these players.