What is a guitar amp?
A simple definition
For electric guitars (and sometimes acoustic guitars), a guitar amp is a device that uses a preamp, power amp, and speaker cab to project the sound waves from electric guitar pickups or humbuckers.
A guitar amplifier, often simply referred to as an "amp," is a device used to amplify the sound produced by an electric guitar or sometimes an acoustic guitar.
It plays a crucial role in shaping the final tone and volume of the instrument, at both the preamp and power amp level.
At its core, a guitar amplifier works by taking the weak electrical signal generated by the pickups on an electric guitar and boosting it to a level that can be projected through a speaker. This amplification process enhances the signal's strength and alters its characteristics (tone settings, distortion, etc.) to produce a sound that is louder, richer, and more suitable for live performances or recording.
Read more: Best guitar amps overall
The Mesa Rectifier Badlander is an example of a tube-powered amp head with a preamp and power amp, but without a speaker cab.
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Guitar Amp Components
A typical guitar amplifier consists of several key components.
- Preamp
- Power amp
- Speaker cab
Preamp
The Preamp is responsible for taking the guitar's input signal and shaping its tone qualities. It allows guitarists to adjust the bass, midrange, and treble frequencies to achieve their desired sound. This is also called a three-band EQ.
Additionally, gain controls are usually included in a preamp, which enables guitarists to control the level of distortion or overdrive in their tone.
Read more: How to use a distortion pedal
Power Amp
Coming out of the preamp, the signal then passes through the power amplifier, which increases the signal's overall volume and prepares it for projection through the speaker(s) into open air.
This is typically called the "Master Output."
The power amp is responsible for providing the necessary wattage to drive the speaker and produce the desired volume levels.
The Line 6 Catalyst is a type of solid state, digital modeling guitar amp.
Speakers
The speaker(s) then convert the electrical signal into audible sound waves. This is the final step in the amplification process.
Different types and configurations of speakers can shift the tonal characteristics of the amplifier. For instance, a single 12-inch speaker may provide a focused sound with more midrange punch, while a setup with multiple speakers, such as a 2 x 12" or 4 x 12" cabinet, can deliver a broader and more powerful sound.
Different brands of speakers can inject even more variety.
Note that guitar amps may or may not include all three of these components. Those that do are called "combo amps", and are the most popular type of amp, at least for beginners.
- Combo Amp: Includes preamp, power amp, and speaker cab
- Amp Head: Includes preamp and power amp
In some cases, the preamp and power amp can be sold as separate units as well, though it's far less common than heads and combo amps.
The Boss Katana 50 is a solid state, digital modeling amp with a preamp, power amp, and built-in speaker cab.
Additional Features
Here are some additional features you might see in a guitar amp:
- Built-in reverb, delay, chorus, or other effects
- Connectivity options, such as built-in direct outputs for recording, headphone jacks for silent practice, and auxiliary inputs for connecting external audio sources.
Types of Guitar Amps
There are three types of guitar amps to keep in mind:
- Tube amps
- Solid state
- Digital amp models
Tube amplifiers, also known as valve amplifiers, use vacuum tubes to amplify the guitar's signal, producing warm and rich tones. Solid-state amplifiers, on the other hand, employ transistors or integrated circuits for amplification, and are typically more affordable.
Digital amplifiers utilize digital signal processing (DSP) technology to replicate the sound of various amplifier types and effects, providing a versatile and often compact solution.
These are often called modeling amps.
Digital and solid state circuits are often used in the same amp.
Wrap Up
A guitar amp seems simple, but there's some nuance that's worth understanding before you go and buy one. It's not as simple and straightforward as one might think.
Hopefully this gets you going in the right direction.
If you have questions, drop them into the comments section below.
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