Going Electric
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Frying Pan
The first commercially successful electric guitar, the so-called "Frying Pan," was developed and marketed by George Beauchamp and Adolph Rickenbacker in 1932. The Frying Pan wasn’t like today’s popular electric guitars – it was an electric Hawaiian model that was played flat in the lap!
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If you have ever compared an electric guitar to an acoustic guitar, you know that they have several important things in common. Both acoustic and electric guitars have strings, they both tune those strings with tuning pegs and they both have frets on a long neck. Down at the body end is where the major differences are found. Some electric guitars have a hollow or semi-hollow body with the resonating cavity found in an acoustic guitar, but the most popular electric guitars have solid bodies. If you pluck a string on an electric guitar that is not plugged in, the sound is barely audible. Without a soundboard and a hollow body, there is nothing to amplify the string's vibrations. So, to produce sound, an electric guitar senses the vibrations of the strings electronically and routes an electronic signal to an amplifier and speaker. The sensing occurs in a magnetic pickup – a bar magnet wrapped with lots of fine wire – mounted under the strings on the guitar's body.
Electromagnetic Music
Coils and magnets can turn electrical energy into motion. In the same way, they can turn motion into electrical energy. In the case of an electric guitar, the vibrating steel strings produce a corresponding vibration in the magnet's magnetic field and therefore a vibrating current in the coil. The pickup's coil sends its signals through a simple circuit (on most guitars). An upper variable resistor adjusts the tone. A second resistor controls the amplitude (volume) of the signal that reaches the jack. From the jack, the signal runs to an amplifier, which drives a speaker.
Image © Andresr/Shutterstock
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Many electric guitars have two or three different pickups located at different points on the body. Each pickup will have a distinctive sound, and multiple pickups can be paired, either in-phase or out, to produce additional variations.
Most electric guitars are completely passive. That is, they consume no power, and you don't have to plug them into a power supply. (Some do have "active" electronics powered by an onboard battery.) The vibration of the strings produces a signal in the pickup coil. That bare, un-amplified signal is what comes out of the guitar and into the amp. The amp's job is to take the guitar's signal and make it audible by boosting it enough to drive a speaker. The fascinating thing about an electric guitar amp is that the amp is actually a part of the instrument.
The role of an electric guitar amp is completely different from the amplifier in a stereo system. A stereo amp is meant to be transparent -- its job is to reproduce and amplify sound with as little distortion as possible. With an electric guitar amp, musicians often seek distortion as well as the option of a "clean" sound. Distortion results when the signal in an amp's circuitry is too powerful for that circuitry. The distortion is actually a part of the desired sound, and many amps are designed so that guitarists can control the level of distortion.
Musicians may also take advantage of feedback loops between the amp and the guitar. If the sound coming out of the amp and speaker is loud enough, it can cause the guitar's strings to vibrate. The musician can hit a note with the guitar, and the amp will cause that string to continue vibrating indefinitely. Both of these concepts -- amp distortion and feedback -- are unique to the electric guitar.
Les Paul
Image © Andrea Leone/Shutterstock
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Les Paul, an already well-known acoustic guitarist, became even more famous when he entered the electric guitar arena. His first, built from a four-by-four piece of pine with a pickup mounted on it, was nicknamed "The Log" -- but his most famous was a model he endorsed, which was introduced by Gibson in 1952.
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