Here’s a frequently asked question: “What’s the difference between distortion and overdrive?”
Good question, since the terms seem so often to be used interchangeably. In Tech Talk’s opinion, however, this is a matter of semantics, because it’s not so much that distortion and overdrive are two separate things (as the phrasing of the question seems to suggest), but rather that one is a form of the other. That is, overdrive is a specific kind of distortion.
It’s one of those situations, in fact, where you can sensibly note that while all overdrive is distortion, not all distortion is overdrive. Of the two terms, distortion is the more general.
For our everyday purposes—practicing, rehearsals, sessions, gigs, etc.—it might help to consider distortion as an umbrella term for any “dirty” guitar sound, regardless of what causes it, be it a torn speaker, a stomp box, a rack effect or an amp cranked up past its capacity for producing a clean sound. Without delving into loads of complicated audio science—and there’s a lot of it—we can generally think of distortion as any signal that’s not clean.
Suffice to say then that there are different kinds of distortion, with overdrive being one among them. Another form of guitar distortion quite separate from overdrive, for example, is fuzz. When you hear “Satisfaction” by the Stones, you are hearing distortion, but the kind of distortion you’re hearing is fuzz, not overdrive. Or when you hear “You Really Got Me” by the Kinks, you’re hearing distortion caused by deliberately damaged speakers (slashed with a razor by Dave Davies himself, in that particular case) rather than overdrive.
Usually, overdrive is considered a particular form of distortion caused by “pushing” an amp past its capability for producing a clean tone. Overdrive is often easily achieved in tube amps because the very nature of tube amp design is that they sound “clean” at lower volumes and distort to some extent at louder volumes.
Now, it is true that there are plenty of overdrive stomp boxes out there, but the effect that these devices aim to achieve is that of an amp cranked past its clean tone capability.
In fact, the key difference between distortion effects and overdrive effects (amp or pedal) is that distortion effects usually aim to produce the same amount of distortion regardless of volume. Overdrive units, on the other hand, function much like tube amps in that they produce cleaner sounds at lower volumes, with distortion increasing as volume increases.
Songs that provide great examples of overdriven amp tone include “Won’t Get Fooled Again” (the Who), “All Right Now” (Free), “Johnny B. Goode” (Chuck Berry), “Pride and Joy” (Stevie Ray Vaughan), a great deal of Richards’ output after “Satisfaction,” and pretty much anything by AC/DC.
We should also note that there is also a tendency to refer to a small amount of distortion, regardless of what creates it, as overdrive, with more heavily broken-up sounds labeled as distortion, although such distinctions purely subjective.