The Nuts and Bolts of Electric Guitars
Recognizing the different parts of the guitar is important, but knowing what makes an electric guitar work as a whole is essential to differentiate it from, say, a bassoon, accordion, or kazoo. Not that there's anything wrong with those instruments, but try doing a windmill (a showy strumming technique where you extend your right arm out and move it in a circular motion, striking the guitar strings once a cycle — Pete Townshend is the windmill's most famous practitioner) with a bassoon and they'll cart you away quicker than your friends can ask the musical question, "Why is the bassoonist having a fit?"
String vibration and pitch
An electric guitar is a string, or stringed, instrument that creates musical sound through a vibrating string. Each string can produce a variety of different notes, but only one at a time. If you want to play two or more notes simultaneously, you must play them on different strings and strike them simultaneously. Because a standard electric guitar has six strings, it can play up to six simultaneous notes, but no more. (Consequently, guitarists more than make up for this "limitation" by playing extremely loudly.)
If you tighten a given length of string to a particular tension and then set it in motion (harpists by plucking, pianistsby striking, violinistsby bowing), the string will vibrate back and forth at a regular rate. This vibration produces a steady tone that we call pitch. The pitch remains the same as long as the string vibrates. As the string's vibrations lose power, or intensity, over time, the note gets quieter, but its pitch doesn't change.
Tension versus length
Two properties determine a string's pitch: tension and length. Therefore, you can change a string's pitch in one of two ways: by changing its tension (which you do when tuning or bending) or by changing its length (which you do when fretting — by changing the length of string allowed to vibrate). You must change pitch to play different notes, whether in a scale, a melody, or a chord progression.
You couldn't do very much with a guitar, however, if the only way to change pitches was to frantically adjust the tension every time you pluck a string. You'd end up looking like the musical equivalent of the circus performer who spins those plates on a stick. So guitarists resort to the other way to change a string's pitch — fretting.
And that's why we have all this fretting about fretting: Fretting is the way guitarists change notes on the electric guitar. Without left-hand fretting, we could strike the guitar and make a lot of noise, but all the notes would sound the same — worse even than a speech by a boring politician.
One of the bigger differences between two icons of electric guitar models, the Gibson Les Paul and the Fender Stratocaster, is that their string lengths are different. The Les Paul has a vibrating string length of 24.75 inches; the Strat (as it's known to its friends) has a vibrating length of 25.5 inches. Not much, maybe, but enough to make a perceptible difference to the hands.
Physics tells us that two different string lengths drawn to produce the same pitch (as they must to be in tune) will have different tensions. The Strat, because it has the longer string length, has slightly higher string tension than the Les Paul. This creates two key differences in playability for the electric guitarist: tighter, or springier, string response and larger frets in the Strat; and looser, or spongier, string response and smaller frets in the Les Paul.
But before you attempt to draw any conclusions, these descriptions are not value judgments; they do not indicate whether one aspect is good or bad versus the other. These qualities merely describe — hopefully without introducing bias or preference — the physical differences between the feel and playability of the different string tensions. Which one you prefer is just that — your preference. Most professional rock guitarists don't even have an absolute, one-choice-fits-all guitar. Instead, they select guitars based on the type of music they want to play, and will have many different guitars at their disposal to handle a variety of musical styles.
Guitar playing requires you to use two hands working together, but performing different actions. This is different than playing, say, the piano or saxophone, where both hands perform the same type of action (striking keys and pressing keys, respectively). Guitar playing has the left hand selecting which notes to sound (by pressing down the strings against frets) and the right hand sounding those notes by striking (or plucking) the strings. And for you lefties, the ones who reverse the strings to play, please understand that "left" and "right" indicate the hand that frets and the hand that picks, respectively. That's not a prejudice against lefties, it's just that guitar convention dictates using "left" and "right" rather than "fretting" and "picking."
At first, this might seem like the musical equivalent of rubbing your stomach and patting your head, but after a while, performing two different actions to produce one sound becomes second nature, and you don't even have to think about it — like walking and chewing gum. And if you can't do that, maybe you should think about running for office instead of playing rock guitar.
Pickups and amplification
Vibrating strings produce the different tones on a guitar. You must be able to hear those tones, however, or you face one of those if-a-tree-falls-in-a-forest questions. For an acoustic guitar, hearing it is no problem because it provides its own amplifier in the form of the hollow sound chamber that boosts its sound . . . well, acoustically.
An electric guitar, on the other hand, makes virtually no acoustic sound at all. (Well, a tiny bit, like a buzzing mosquito, but nowhere near enough to fill a stadium or anger your next-door neighbors.) An electric instrument creates its tones entirely through electronic means. The vibrating string is still the source of the sound, but a hollow wood chamber isn't what makes those vibrations audible. Instead, the vibrations disturb, or modulate, the magnetic field that the pickups — wire-wrapped magnets positioned underneath the strings — produce. As the vibrations of the strings modulate the pickup's magnetic field, the pickup produces a tiny electric current.
If you remember from eighth-grade science, wrapping wire around a magnet creates a small current in the wire. If you then take any magnetic substance and disturb the magnetic field around that wire, you create fluctuations in the current itself. A taut steel string vibrating at the rate of 440 times per second creates a current that itself fluctuates 440 times per second. Pass that current through an amplifier and then a speaker and you hear the musical tone A. More specifically, you hear the A above middle C, which is the standard absolute tuning reference in modern music — from the New York Philharmonic to the Rolling Stones to Metallica.