How Interesting Things Work

Electric Guitars and Amplifiers

The main purpose of an amplifier is to "amplify" the vibrations given by the signal between a guitar and the amp. That's the most basic point. However, it's a bit more complicated than that.

In your average electric guitar, plucking the strings while unplugged is pretty quiet, becuase there is no body resonance, which is the phenomenon that makes an acoustic guitar or a hollow-body electric guitar amplify itself. The entire structure of a guitar goes something like this:

Headstock- The "Head" of the guitar, where the tuners and the beginning of the strings are.
Neck- Where the main strings are, while the fretboard also lies in this area, in which case, there are usually around 22-26 frets on your average electric, but some custom guitars call for more upper ranges of notes, giving a total of an astonishingly approximate 33 frets.
Sound Hole (Acoustic/ Some Hollow-bodies) - This is the system that a self amplifying guitar uses. By having a hollow body, the vibrations generated by a plucking of the string travel into the guitar and reverberate (hence an effect called "reverb"), or "bounce" around the inside of the body of the guitar. Multiple impulses of these "bouncing" waves may add together their amplitudes, giving a much louder sound than a packed-body electric guitar.
Bridge - this is where all strings stop and wrap around to keep tight and playable. On Tremolo-equipped electric guitars, there will be a hole to insert a "whammy bar" or tremolo arm, which allows for massive pitch-sweeping and pitch-diving and pitch-insanity tricks on the guitar. However, because this tightens and loosens the strings quickly it will have major tuning problems after all the pitch craziness. So some guitars have been built with this interesting and efficient technique to stay in tune, called the floating tremolo bridge setup, or also known as the Floyd Rose bridge and tremolo setup. Point is, this technique allowed the strings to stay in tune becuase at the point in between the headstock and the neck, there is a very complicated system that "clamps" down on the strings, making them stay tuned to the way they are tuned, allowing players to not have to inconveniently mess with the tuning all the time. However, becuase of this setup, changing the strings is very complicated. You have to remove the clamps, then remove the bridge, and the weirdest part is, you have to remove the back part of the guitar's body, and pull the strings out of there, being careful to not break the springs that give life to the floating tremolo bridge setup, and finally, put new strings in there, put the seal back on, make sure the strungs are perfectly in tune, put the clamps back on, and do a last check to make sure it's all good. It's very complex, but the result of the hard work is always satisfying.
Pickup- On electric guitars, the pickup is what transfers the signal between the guitar and the cable to the amp. The pickup works by being a magnetic system, and has magnets that attracts vibrations, converts it to electric current as audio data, sends it over the cable, and the amp/audio device picks up the signal as audio data. A single coil pickup is a pickup that has a magnet wrapped around it once. A double coil has it wrapped twice. Back when electric started getting popular, some guitarists complained about a low hum that was heard even when muting the strings completely, that came from the guitar. This low hum is a vibration that is generated by the magnet itself, as the coil is trying to attract vibrations at a fast rate, giving this humming sound. So electric pickup companies tried to work a way around this hum, and they found that putting two magnets at opposite polarities would cancel each others' humming, but still remain efficient to picking up vibrations from the strings. This is today called the humbucker pickup, which i guess is supposed to mean "buck off, hum". Anyway, some guitarists also found out that placing the pickup at different positions can cause vastly different tones, even on the clean and completely untweaked channels of amps. So they experimented with putting single coil, double coil, and humbucker pickups at different positions in different orders, and it made a wide variety of interesting tones and such, and metal guitarists liked this a lot too. Moving on.

So that's the basic way guitars work. Now let's talk about Amps.

In amplifiers, there are a few stages to go through. Amps are digital and electronic, so they do some interesting things to sounds. In fact, the classic crunching overdriven tone from metal/rock/etc, was actually caused by guitarists' electric guitar speakers getting a bit broken, meaning that these speakers couldn't handle shaping the waves produced properly, so this effect was literally called "Distortion", which guitarists, memers, and electronic musicians love today. The way that an amplifier works is something like this:

PreAmp: this is the configuration stage that shapes the sound before the sound is made loud and distorted.
Amp: this is the configuration formulas for driving the sound
PostAmp: similar to musicians mastering their songs in the Digital Audio Workstation, this is the configuration stage after the amplification has occured, and it is for keeping the final sound controlled.

In the PreAmp stage, you normally have a pre EQ. EQ is short for EQualizer, and this controls the frequencies of the sound, where you can shape your sound with high quality. For example, you can bring up the bass way more than you can with those ridiculous "bass-boosting" headphones, or you can turn it down a bit. Some genres of music prefer a lot of things, and metal is one of my favorites. In Metal music, as an example, the pre EQ is to usually bring up the Bass and Treble (Treble is high frequencies, and this is also labelled as HG (High-gain)), and turn the Middle frequencies down. Also preffered is to bring up the presence, which is a somewhat upper mid-high range (specifically between 4kHz and 6kHz) which makes for a brighter, clearer, better tone for metal an rock. After the EQ stage, you have the choice of some different channels depending on which amp you have. Almost all amps have a Overdrive and Clean channel. Clean just amplifies the sound a bit and keeps it clean.
Overdrive is a bit complicated.

In overdrive mode, you can choose the amount of drive, or gain, you desire. Basically, if you look at the sound of a guitar through a basic oscilliscope (tool for visualizing waveforms) then you can see that as you bring up the drive in a tube amp, you see that the wave more and more may resemble a square-like shape. not really square, but more like just a hard bottom line, and straight up, and a hard top line. The reason that distortion happens is when you make the ceiling of the amplification as the ceiling of the oscilliscope, so for example, the wave can't go above this point, so it has to straight up stop in a line until the value of the waveform is no longer above the ceiling. This causes an extraordinary variety of tones, as waveforms behave like that. The wave also has to follow this strict pattern of wave-shaping, and the wave shaping in a tube amp is "square-like". Other amps have all sorts of different types of wave shaping patterns, but the classic one is tube.

Finally, the post amp stage is mainly just an eq to balance out the frequencies of the final sound and a master volume control to keep it mixed well in a song.
After all that, sometimes amp proccessors hook up to something called a cabinet, which... for some odd reason makes the tone shape differently, as microphones are usually recording cabinet speakers, and placing the microphone at different positions can cause different tones. Sounds familiar to the pickups, huh?

And that is how an Electric Guitar and Amplifier works. Hope you enjoyed this bit of a technical electric guitar lesson, and thanks for reading the first chapter of my book explaining how things work. :3

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