There are few inventions that have been as crucial to the evolution of pop and rock music as the guitar amplifier.
Indeed, many cite the 1951 Sun Records recording session of Jackie Brenston and his Delta Cats' iconic "Rocket 88" -- one of the earliest instances of distorted electric guitar on record -- as the moment rock 'n' roll was born.
In fact, the roots of rock and roll began much earlier, albeit with no less significance placed on the amplified electric guitar -- in Charlie Christian's solos of the 1930s, for example, one can hear the basis of T-Bone Walker's, and later, Chuck Berry's guitar soloing styles.
Fast forward to the present day. Amplified instruments continue to be the driving force behind contemporary music of all genres. From rock and punk all the way to electronic dance music, an amplified signal is all it takes to bring the noise and get the party started.
We even rely on amplifier technologies in aspects of life that have nothing at all to do with "turning up." But it all comes back to the vacuum tube and the complex technologies that were founded early on as a means to pave a future in telecommunications, namely radio technology.
So what is an amplifier? In this article, we will explore the origins of the amplifier, cover some historical applications of the technology, and somehow bring it all back to the inevitable: your guitar rig.
Read on to learn more than you've ever thought you needed to know about this world-changing technology.
Historical Background of the Amplifier
The first vacuum tube amplifier was created by American inventor Lee De Forest in 1906 to be used as a component in radio receivers. It amplified weak electrical signals, making it possible to receive and amplify radio signals, which was a significant advancement in the field of telecommunications.
This had widespread implications beyond radio, including making possible the vast telephone switching networks of yesteryear. But arguably more important (well, to some of us anyway) was the vacuum tube amplifier's effect on the world of music production.
It only took a few years for this burgeoning new technology to make its way into the capable hands of music buffs, with the introduction of the Rickenbacker "Frying Pan" electric guitar and its accompanying amplifier making the rounds as early as the 1920s.
By the 1930s and 40s, such mold-breaking innovators as Les Paul and Leo Fender were conducting their own experiments with vacuum tube technology, both developing their own amp prototypes over the years to accompany their namesake solidbody electric guitars.
Fender in particular struck a chord with his tube amplifiers in the 1950s and 60s, and soon the rock and roll revolution was underway, changing not only how we created and listened to music, but also arguably overhauling the very values upon which our society stands.
While you're fine-tuning your sound, why not explore the differences between gain and volume?
How Does Amplification Work?
Amplification can be simply defined as boosting, intensifying, or otherwise strengthening a signal, electrical current, or sound. In the case of modern amplifier technology, we are technically boosting sounds in the form of electrical audio signals.
The Basics: Vacuum Tube Amplification Process
Without getting too wonky, we'll attempt to briefly explain how this process works, using an electric guitar and vacuum tube amp as our first example.
Your electric guitar's magnetic pickup captures the strings' vibrations when plucked or strummed through a process known as electromagnetic induction. In short, the magnets in the pickup create a magnetic field around the strings, and this field is disrupted by the vibrations of the strings.
The audio signal is then "picked up" by the pickup coil and sent to the output jack of the guitar, where it becomes the guitar's "output signal."
Through your instrument cable it goes, becoming in the process your amplifier's "input signal." This small input signal is then run through the amplifier circuit, which mainly consists of a set of vacuum tubes, where electrons are able to flow from one end (the cathode) to the other (the anode).
By playing a loud sound on your instrument, you're creating a positive signal output that effectively throttles the flow of electrons (which, as we remember from school, hold a negative charge), which correspond to the input signal's waveforms.
This creates a stronger signal at the anode, becoming the amplifier's signal output. This signal is then carried to a speaker, where yet another magnetic coil is made to vibrate in reaction to the signal, which then in turn vibrates the speaker's cone, creating the waves in the air that we hear as sound.
Solid State/Transistor Amplifiers
The solid-state or transistor amplification process is not dissimilar to that of the vacuum tube process; in this case, transistors are used to regulate the flow of electronic currents rather than vacuum tubes.
And what exactly are transistors, you ask? Transistors are essentially semiconductors that are able to use what is called a biasing voltage to modulate the flow of electrical currents, much like the way a vacuum tube uses a vacuum or field of low-density gas to allow this same type of electron flow.
When the biasing voltage is adjusted, the amplitude of the signal modulates with it. And voila! You have an amplified output signal that can then be carried to a speaker just as described above in the tube amp example.
The Digital Amplification Process: A Primer
Digital amplification, also known as Class D amplification, is an altogether different process that nonetheless yields similar results (an amplified signal).
In this case, the guitar's output signal is converted from an analog signal to a digital one through a process known as, you guessed it, analog-to-digital conversion. This is achieved by sampling the signal at discrete intervals and quantizing that signal into digital values, each representing the signal's amplitude at its corresponding interval point.
These digitized signals are then processed, applying equalization, volume control, and other effects. Finally, the signal is amplified through a process known as pulse width modulation. In this process, the digital audio signal is used to control the width of pulses in a high-frequency carrier signal, replicating the audio signal, only amplified.
What are the Key Components of an Amplifier?
Any amplifier is composed of a number of primary components, all of which play an integral part in the amplification process. These may include, but are not limited to, a power supply, input and output terminals, active elements (transistors and tubes), and passive elements (resistors, capacitors).
Power Supply
Let's start with the power supply. The power supply is essentially responsible for providing the amp with the appropriate voltage and current levels required for operation, ensuring stable and reliable performance.
An amp's power supply (the cable that plugs into the wall and its attached assembly of components) provides a stable DC (direct current) voltage to the amp circuit, allowing it to operate as intended.
It also provides adequate current flow to engage the amp's circuitry and provides voltage biasing to establish the necessary idle conditions for the amp (i.e. keep it running when there is no input signal).
Input and Output Terminals
Next, the amp's input and output terminals are there to feed the weak input signal into the amplifier circuit and guide the amplified signal out of the amp, in most cases, to a speaker.
The input is generally going to be your standard 1/4" jack into which you plug your instrument cable, either straight from your guitar or from your effects pedal chain.
The output terminal is either out of sight, inside your amp's assembly (if it's a combo amp), or, in the case of a separate head/cabinet configuration, it will be an external speaker cable jack that will then in turn feed into your speaker cabinet's input terminal.
Active Elements
The term "active elements" refers to the components in the amplifier that actively amplify and shape the sound -- this is essentially where the magic happens.
In your tube amps, it's the tubes. Solid-state amps have transistors. Digital modelers have DSPs. No matter what type of amplifier we're talking about, the active elements are the bits doing the heavy lifting.
Passive Elements
The passive elements are the resistors, capacitors, coils, as well as the potentiometers (pots/knobs) speaker components themselves -- any element that doesn't have its own power source, but rather affects the signal through passive means: filtering, tone shaping, and impedance matching.
These elements have just as much importance to your amp's sound as the active elements, and in many cases are responsible for the ability to fine-tune your tone, including the basics like volume control.
What are the Different Types of Amplifiers?
There are many different kinds of amplifiers out there -- and, just as there are other uses for amplifier technology than just instrument amplification, there are whole types of amps that have little to no application in the field of music.
So we're going to focus on the three main types of amplifiers that are used in music (primarily for guitar). They are:
Tube Amplifiers
Tube amps are the original, iconic amps that started it all. Fender, Marshall, Vox, Orange, you name it -- the legendary tones upon which much of today's music was built were powered by tube amp technology.
To this day, tube amps are sought-after for warm, rich, nuanced tone with unparalleled dynamic range and sensitivity -- perfect for musical expression, whether it's rock, blues, country, or jazz.
Solid-State Amplifiers
Solid-state amplifiers bring a lot to the table as well: versatility, reliability, and headroom (the maximum volume attainable without distorting the signal).
Many players seek solid-state amps because they require less attention than tube amps. Others, like many jazz players and pedal steel players, prefer solid-state amps because of their ability to produce glassy clean tones even at high volumes.
Digital Amplifiers
Finally, digital amplifiers, or modeling amps, are amps that use DSP (Digital signal processing) to create a versatile range of tones digitally rather than relying on physical elements like vacuum tubes.
The best digital modeling amps can replicate practically any tone you could ever want, and as such are great for recording, beginners who are just finding their sound, or, really, anyone who likes having a lot of fun playing guitar.
How to Choose the Right Amplifier for Your Guitar
If you've made it this far, you now know more about amplifiers than you ever thought you needed to.
But that still might not quite solve the biggest question of all: which amp is right for you? In order to help you find a solution, we'll explore in this section the different factors you might want to consider when shopping for a new amp.
Tone
One of the main factors you're going to want to select for is the amp's tonal qualities and how they relate to the styles of music you intend to use your amplifier for.
Tube amps are the preferred style of amplifier for blues and classic rock, favored for their expressiveness and tube overdrive and saturation. These qualities are sought after not only in emulation of classic amplifier sounds but also because they allow for a dynamic range that is desirable for these styles in particular.
Solid-state amps are great for such varied applications as hard rock and metal, all the way to jazz and country. Solid-state amps are not only reliable, but they allow for a consistency of tone that are valued in these genres. Whether you want relentless crunch or glassy cleans, a solid-state amp is a dependable option for you.
Finally, digital modeling amps can be used for just about any genre. Thanks to digital amp modeling technology, these amps are capable of reproducing just about any tone you can think of.
That being said, however, some more experienced players are likely to note that you can still detect a difference between a real tube amp and a simulator. Be that as it may, fans of modeling amps just might be having a lot more fun than the rest of us!
Power
Another very important factor to consider is how much power you're going to need from your amplifier.
Guitar amps come in a wide range of power ratings, from one watt all the way up into the hundreds! It's very important to select an amplifier that's going to suit your needs.
For example, if you're strictly a bedroom player, you likely aren't going to require an Orange Rockerverb 100. Instead, opt for a small combo like the Orange Crush 20RT.
That being said, even a 20-watt combo is enough for most gigs, and more than enough to disturb your neighbors. Heavy metal players and professional arena-level acts will probably need more power, but for the average player's purposes, 15-30 watts is more than sufficient.
Compatibility
When selecting your amp, you should be sure it's compatible with any external effects or speakers you wish to use.
For example, if you wish to use effects, you may want to pick an amp with an effects loop, which allows you to run your effects through your signal unadulterated by the amp's preamp stage, giving you a more pristine tone, although pedals can be generally jacked into your amp's input as well.
And please, please be sure that when selecting your amp, you don't pick out an amplifier head without also purchasing a speaker cabinet. You will be very disappointed after spending your entire amp budget on a piece of equipment that is unable to issue forth any sound on its own.
Budget
Finally, speaking of your amp budget, you're going to want to consider this factor very carefully. Music equipment will often set you back a pretty penny, and as such, is worth considering more as an investment than a purchase.
Indeed, much music equipment (particularly vintage, although this isn't always the case) holds its value quite well, and in some cases even appreciates in value over time. But we digress.
What we mean to say is, it's worth investing a significant amount of money into quality equipment if you can afford to. While you should by no means overextend yourself, you will be pleased if you buy a piece of equipment that you will be happy with for years, rather than having to upgrade as you progress.
Best Guitar Amp Brands
While there is no means of accurately determining what the best amplifier is for everyone's individual needs, there are a few standout brands that have the reputation of being among the best guitar amps money can buy.
For more information about these great amp brands and more, you can check out our full list of the best guitar amp brands here.
What is an Amplifier: FAQs
Why is an amplifier important in a sound system or musical setup?
An amplifier bears a distinctly important responsibility in any sound system or musical setup: amplifying, or making louder, a weak signal (like the tinny twanging of your electric guitar strings) into a formidable enough signal to drive a speaker and be heard.
What's the difference between analog and digital amplifiers?
Analog amplifiers like tube amps and solid-state transistor amps carry a signal in the form of electrical energy from one conductor to another, amplifying and otherwise shaping the signal in the process through purely physical means.
Digital amplifiers, on the other hand, convert analog signals to digital ones by sampling the signal and then quantizing it into digital values. This digital signal can then be modified through digital signal processing before finally driving a speaker and producing a sound.
What does 'gain' mean in the context of amplifiers?
"Gain" refers to the degree to which a signal is amplified. It determines how much larger the output signal will be compared to the input signal.
There are two types of gain: preamp gain and power amp gain. But what people often really mean when they refer to "gain" is preamp gain, where a signal can be boosted but also significantly altered by distortion before proceeding to the power amp stage.
What are the differences between preamps and power amplifiers?
The preamp is the initial stage in an amplifier. Its primary function is to take the weak input signal and amplify it to a level suitable for further processing or for driving a power amplifier.
Preamps are responsible for the initial amplification of the signal and often provide tone-shaping controls, such as EQ (equalization) settings, volume, and gain.
The power amp, or power amplifier, is the stage that comes after the preamp. Its primary function is to take the preamplified signal and further boost its strength to a level suitable for driving loudspeakers.
Power amps provide the necessary power to make the sound audible through speakers. They focus on providing clean and high-current amplification with minimal distortion.
How is an amplifier's power measured?
An amplifier's power is typically measured in watts (W). This power measurement provides information about how much electrical energy the amplifier can convert into audio output power.
Keep in mind that an amp's power does not necessarily determine its output, especially when you're combining amp heads with speaker cabs -- things can get a bit tricky.
How does the size or wattage of a guitar amp affect its sound?
Tube amps in particular will have different sonic qualities based on the amp's size or wattage of its output. Essentially, the larger or higher-wattage your amp, the higher you can push the amp's volume and maintain a clean, undistorted signal.
That might lead some people to conclude that smaller tube amps are "dirtier," or easier to get a distorted sound out of. While this isn't strictly true, it is true that you're more likely to get away with pushing a smaller (say, 15-20w) amp to the point of distortion, and still being invited back to that venue.
Conclusion
Answering the question "What is an amplifier?" isn't as simple as it might seem.
After all, from its humble origins as a component intended for telecommunications hardware all the way to cultural icon, the amplifier has undergone quite a journey over the course of the last century.
But nevertheless, we hope you were able to learn a lot about these incredible tools from this informational article. From how amplifiers work, to the names of some of the crucial components, and even what kind of amp might be the best for you, we've tried our best to demystify the electric guitar's best friend.
If you'd like to put your newfound knowledge to the test and pick up a new amplifier for yourself, please don't hesitate to check out our roundup of the best guitar amps on the market right now, as well as our roundups for individual amp brands and more.
Thanks again for reading, and until next time, keep on crankin' it up!
