Читать книгу Blues Guitar For Dummies - Jon Chappell - Страница 45

As soon as electric guitars were available, blues players of the day made the transition quickly and easily from their acoustic versions. An electric guitar uses the same approach to neck and frets and the way the left and right hands share separate but equally important roles (see the preceding section for the basics), but it provides some aspects that the acoustic guitar can’t do or can’t do as well, in addition to the most obvious advantage: increased volume through electronic amplification. The amplified electric guitar certainly changed the music world, but in many more ways than just being able to be heard over the rest of the band. The entire tonal character changed, in addition to the way you had to play it.

Technologically speaking, an electric guitar is no more complicated than an eighth-grade science project: A wire (the string) hovers over a magnet (the pickup), which forms a magnetic field. When you set the wire in motion (by plucking it), the vibrating, or oscillating, string creates a disturbance in the magnetic field, which produces an electrical current. This current travels down a cord (the one sticking out the side of your guitar) and into an amplifier, where it’s cranked up to levels that people can hear — and in some cases, really hear. Figure 2-5 shows a close-up of the sound-producing parts of an electric guitar: the string and pickup.

FIGURE 2-5: The makers of electric sound, reporting for duty.

Naturally, there’s a lot more to the way electric guitars make music than what I describe here, but what’s significant is that an electric guitar doesn’t make its sound acoustically. Even though you can hear the string when the guitar’s not plugged in, that’s not what the guitar “hears.” The guitar converts a disturbance in the pickup’s magnetic field to a current. This all-electronic process is different than “pre-electric guitar amplification,” which consisted of placing a microphone in front of a guitar.

In an electric guitar, you must use metal strings, because nylon ones don’t have magnetic properties. The fact that you need only a metal wire and a pickup to make sound — rather than a resonating chamber — meant electric guitars could be built differently from their acoustic counterparts. And they were played differently, though that took some time to evolve.