How Do Electric Guitars Work

If you are into building guitars (chances are since you are on a custom guitar building site you most likely are) then you probably have spent quite a bit of time tinkering with your guitar's look and feel. But what about the sound it produces? How does the simple act of picking a guitar string produce sound from an amplifier?

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In the article below we are going to cover the basics of how an electric guitar works to produce sound. This should be of interest to anyone making their own guitar as it will give you an insight into what's going on inside the guitar and perhaps give you some ideas on how to modify and experiment with the electronics of your guitar.

How sound is created and controlled

While it's true that the timber, hardware and your own playing ability can affect your tone we are going to concentrate on the parts responsible for creating or controlling sound e.g. your pickups, tone, volume pots and pickup selector switch and the way these components all work together.

In a very basic sense, your pickups create a magnetic field that is disturbed when guitar strings are vibrated above it. This, in turn, converts the vibration of the guitar strings into a current. The current is then sent through to your output jack where the signal then passes through your lead into your amplifier, where it is amplified. Different gauge strings vibrate at different rates e.g. an A string will typically vibrate at 440 cycles per second (440 hertz) which creates a current of 440 hertz in the pickup.

Along the way, this signal passes through your volume and tone pots where you can either increase the amount of signal and specific frequencies of the signal which in turn affects your overall volume and tone. The pickup selector switch allows you to choose which pickup (or a combination of pickups) are active.

Got it? Ok, now let's take a look in more detail at each component.

Pickups

We have covered pickups here before so rather than running over old ground I suggest you read that article to get an understanding of the different types of pickups an electric guitar uses and how they work in greater detail. For the purpose of this article, however, all sound starts with your pickups. Pickups are essentially magnets, generally 6 small magnets wrapped in a very fine copper wire (over 7000 times), and can be better described as magnetic wire coils.

For the purpose of this article, however, all sound starts with your pickups. Pickups are essentially magnets, generally 6 small magnets wrapped in a very fine copper wire (over 7000 times), and can be better described as magnetic wire coils.

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If a metallic object (such as an electric guitar string for example) is vibrated above a magnetic coil the magnetic field is disturbed and an electrical current is produced. This current then travels through the pickups connecting wires, eventually making it's way to your output jack where it is transferred to your guitar lead and ultimately to your guitar amp where the small signal is amplified to produce the sound associated with an electric guitar.

Different pickups (by virtue of their composition and the way they are assembled) produce variations of this current which in turn affect the final sound you hear from your amplifier.

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Volume and Tone Knobs

Technically the knobs are just the parts you turn when adjusting your volume or sound. When you remove the knobs however you are left with the pots (potentiometers) which are used for both volume and tone control.

They look identical and almost are but there are differences in the way a volume pot and a tone pot is wired, which will make more sense by the end of this article.

Pots generally come in two types: 500k or 250k.

K refers to 1000 ohms and is a measure of resistance, which is the amount of resistance the signal from your pickup receives before being passed to your output. As a result, increasing or decreasing the amount of resistance your output receives via your volume pot affects the overall volume of your guitar.

For example, a volume pot controls voltage from your pickups before it is passed to the output jack. As you are no doubt aware your volume is measured between 0 and 10.

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When the volume knob is turned right back, the resistance is very high, resulting in less voltage being passed on. On the other hand, there is no resistance when your volume knob is turned to 10 which results in a clear signal and full voltage.

Tone pots are similar to volume pots except they are wired in such a way as to only increase resistance on the high-end allowing the low-end signal to pass through unheeded. As you increase or decrease the amount of high end by adjusting your tone knob, your tone changes accordingly. Tone pots can be better thought of as filters, they filter high-end frequencies that ultimately affect your overall tone.

Selector Switches

The pickup selector switch as the name implies allows you to select which pickup produces sound. In some cases, it will be your neck pickup, bridge pickup or a combination of both.

In other cases, such as the Fender Stratocaster there are three pickups which utilize a 5-way selector switch. This also allows each pickup to be isolated or used in combination.

How does this impact on your sound?

Basically, the positioning of the pickups has an effect on the frequencies detected. For example, string tension is at its highest closer to the bridge so the bridge pickup generally picks up higher frequencies while the string tension is noticeably lower closer to the neck pickup and a lower end tone is produced.

Summary

I hope the information above better helps you understand how electric guitars work to produce sound. While there are any number of variations that allow for more control over tonal variety the fundamental components (pickups, pots and selector switches) have not changed considerably over time.