Guitar amplifier facts for kids
A guitar amplifier (or amp) is a special electronic device that makes the sound of an electric guitar, bass guitar, or acoustic guitar much louder. It also helps shape the guitar's sound. Imagine your guitar's sound as a tiny whisper; the amp turns it into a powerful voice!
Amps come in two main types:
- A combo amp has everything in one box: the amplifier parts and the speakers.
- A head is just the amplifier part. It needs to be connected to separate speaker cabinets to make sound.
Guitar amps can be small for practicing at home or huge for playing on big stages. Besides making the sound louder, amps can change the tone. They can make the sound brighter, deeper, or even create a cool, fuzzy sound called distortion (also known as overdrive). Many amps also have built-in effects like reverb, which makes the sound echo a bit, like in a big hall.
The first amps appeared in 1928. But they became really popular in the 1950s when electric guitars became common. Famous amp brands include Fender, Marshall, and Vox. For guitarists, their amp and how they set its controls are super important for their unique sound! Historically, amps used vacuum tubes, but modern ones also use solid-state parts or digital technology. Guitarists often use external effects pedals to change their sound before it reaches the amp.
Contents
How Guitar Amps Started
Early Days: 1920s–1940s
Big sound systems were first made for public events and movie theaters. In the 1920s, these systems became smaller and cheaper. This made them popular for musicians, especially those playing lap steel guitars.
The very first guitar amps came out in 1928 from companies like Stromberg-Voisinet and Vega. They were simple, often just a wooden box with a speaker and a volume knob. Early amps were not very powerful, usually less than 10 watts.
A company called Electro String Instruments made an amp in 1932. Its design, a small rectangular wooden box with a handle, became a model for many amps before World War II.
In the mid-1940s, Leo Fender started his own company, Fender. His first amps had wooden cases and wide control panels, looking a bit like old TVs. These early amps weren't super loud. When players turned them up all the way, the sound would "clip." This meant it lost some high and low sounds but gained a cool, fuzzy sound called distortion. This "mistake" became a beloved part of electric guitar music! The Fender Deluxe amp from 1948, with its special tweed covering, became a classic.
Rock and Roll Era: 1950s–1960s
In 1950, Fender released its first popular solid-body electric guitars, like the Telecaster. These guitars helped stop unwanted feedback when amplified. Fender also made famous amps like the Fender Twin and the Fender Bassman. The Bassman was great for bass guitars, but guitarists loved its powerful distortion too!
The Bassman even inspired Marshall to create their first amp, the JTM45. Another famous amp, the Vox AC30, came out in 1958. It was known for its bright, "jangly" sound and was used by many bands during the British Invasion.
As bands like The Who wanted even more power, Marshall released the 100-watt Marshall Super Lead in 1965. This was a "head" amp, meaning it connected to separate speaker cabinets. When paired with several cabinets, it created the famous "Marshall stack." This powerful setup helped define the sound of rock and roll.
During the 1960s, Fender kept improving its amps. The Fender Twin Reverb became famous for its clear, undistorted sounds. Some companies, like Peavey, started using transistors instead of older vacuum tubes in their amps. By the 1970s, many brands offered transistor amps, with the Roland Jazz Chorus becoming a popular choice for clean tones.
Louder and More Distortion: 1970s–1980s
As rock music got heavier, guitarists wanted even more distortion. Old amps needed to be played super loud to get that fuzzy sound, which wasn't always practical. So, players started using effects pedals like the Fuzz-Tone to get distortion at any volume.
Soon, technicians began "hot-rodding" (modifying) Fender amps. They added a "master volume" control. This let players get lots of preamp distortion without making the amp deafeningly loud. Mesa/Boogie founder Randall Smith was one of these pioneers. His modified Fenders led to the brand's famous Mark series, which created more distortion than ever before. This was the birth of "high-gain" amps!
Heavy metal bands like Black Sabbath inspired a demand for even more aggressive sounds. Marshall responded with the JCM800 in 1981, which became a favorite for hard rock and metal. Mesa/Boogie also kept improving their Mark series, adding features like channel-switching. Their Mark IIC+ model became famous for its tight, aggressive tone, used by bands like Metallica. These amps helped bridge the gap between older "vintage" sounds and modern heavy tones.
By the end of the 1980s, many professional guitarists used complex setups with multiple amps and effects in large racks.
Modern Amps: 1990s–Today
In the 1990s, a new style of music called grunge brought back simpler amps and effects. Also, many "boutique" amp builders started making new amps inspired by classic designs. Mesa/Boogie's Dual Rectifier became a top choice for high-gain sounds in this decade.
Around this time, digital modeling technology began to grow. Companies like Line 6 released amps and devices that could digitally copy the sounds of many different famous amplifiers and speaker cabinets. At first, these were mostly for practice.
But in 2006, Fractal Audio released the Axe-FX, which was good enough for professional use. Then, in 2011, the Kemper Profiler came out. It could "profile" or "capture" the exact sound of a real amp and speaker setup, creating a digital copy.
Today, there's a big debate: which is better, traditional tube amps or digital modelers? Tube amp fans love the classic feel and "soul" of analog sound. Modeler users appreciate how portable, consistent, and reliable digital amps are.
Many tube amp makers now add digital features, like impulse responses (IRs), which are digital copies of speaker cabinets. This makes home recording easier. Smaller, "lunchbox" amps also became popular, like the 15-watt Orange Tiny Terror, released in 2006. In 2016, Boss launched its Boss Katana line, which mixes analog and digital tech, becoming a bestseller.
Digital modeling keeps getting better and cheaper. Brands like Neural DSP use AI and machine learning to create amazing virtual amps and effects. Their Quad Cortex, released in 2020, is a powerful example of this new technology.
How Guitar Amps Work
Guitar amplifiers usually have two main parts that make the sound louder. They also have controls to change the sound's tone. These controls often include knobs for bass (low sounds) and treble (high sounds), just like on a home stereo. More advanced amps might have controls for midrange sounds or a "presence" control for very high frequencies. Some even have a graphic equalizer, which lets you adjust many different sound frequencies.
The first part is the preamplifier. It takes the tiny signal from your guitar and makes it a bit stronger. The preamp also shapes the tone. If you turn up the preamp a lot, it can create that cool overdrive sound.
The second part is the power amplifier. This part takes the signal from the preamp and makes it powerful enough to drive the loudspeakers, which then create the actual sound you hear.
You can change your guitar's sound in many ways:
- Using controls on your guitar itself.
- Adding effects pedals between your guitar and the amp, like a wah-wah pedal or chorus.
- Using special circuits inside the amp.
Amps can use old-school vacuum tubes (also called valves) or modern solid-state (transistor) parts, or even a mix of both.
As mentioned, amps come as a "combo" (amp and speakers in one box) or a "head" (amp only, connected to separate speaker cabinets). Speaker cabinets can have one speaker, or many, like four 10-inch speakers or four 12-inch speakers.
Guitar amps vary a lot in price. Small practice amps for beginners can be very affordable. Professional amps for famous musicians can cost a lot more. Most combo amps have a handle for carrying, and many have reinforced corners to protect them.
The control knobs are usually on the front of the amp. Simple amps might only have volume, bass, and treble. More advanced amps can have controls for preamp gain, distortion, master volume, bass, mid, treble, and reverb. There's usually a 1/4-inch input jack for your guitar cable.
More expensive amps might have extra connections on the back. These can include outputs to send your sound to another amp or a recording device, inputs for other instruments, or jacks for effects pedals. Some amps even have a special input for a microphone, so you can sing through the amp too!
Most guitar amps need to be plugged into a wall outlet. But some small practice amps can run on batteries, perfect for playing music outdoors.
Different Kinds of Amps
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As we learned, a combo amp has the amplifier and speakers in one cabinet. A head amp is separate and connects to one or more speaker cabinets.
Amps also come in different power levels. Small "practice amps" might have just 10 watts and a small speaker, great for beginners. Medium amps (30-50 watts) with bigger speakers are good for band rehearsals or small shows. For big concerts, guitarists might use 100-watt (or more) heads with large speaker cabinets. Bass players usually need much more powerful amps to make those low notes sound clear and strong.
Tube Amps
Tube amps use special glass tubes called vacuum tubes (or valves in some places) to make the sound louder. This was the main technology until the 1970s. Tubes are delicate and need to be replaced sometimes.
Even though it's older technology, many guitarists still love tube amps. They believe tube amps create a "warmer" sound and a more natural, rich overdrive when pushed hard. It's a classic sound that many famous guitarists use!
Solid-State Amps
Solid-state amps use modern transistors and other electronic parts. These amps are usually cheaper to make, more reliable, and lighter than tube amps. They are also tougher and less likely to break if bumped.
Most affordable and mid-priced amps today are solid-state. While many professional guitarists still prefer tubes, some jazz guitarists like the very "clean" sound of solid-state amps. The Roland Jazz Chorus is a famous example of a solid-state amp known for its clear tones.
Hybrid Amps
A hybrid amp mixes both tube and solid-state technology. For example, some might have a tube preamp (for that warm tone) and a solid-state power amp (for reliability and power). Other hybrids might have a solid-state preamp and a tube power amp. This combination tries to get the best of both worlds!
Modeling Amps
Modeling amps use computer technology to create many different sounds. They can digitally copy the sounds of famous tube amps, different speaker cabinets, and even microphones. It's like having dozens of amps in one box!
You can program these amps to get almost any sound you can imagine. Companies like Line 6 helped make modeling amps popular. They are great for practicing, recording, and even live shows because they are so versatile and often lighter than carrying many different traditional amps.
Acoustic Amps
Acoustic amplifiers are made specifically for acoustic guitars and other acoustic instruments. Unlike electric guitar amps, acoustic amps are designed to make the instrument sound as natural and "uncolored" as possible. They aim for a very clear, clean sound.
These amps often have powerful amplifiers to keep the sound clean, even at high volumes. Many acoustic amps also include simple mixers, so you can plug in both a pickup and a microphone at the same time. They often have built-in effects like reverb and special features to stop unwanted feedback.
Amp Stacks
When you see an amp head sitting on top of one or more speaker cabinets, that's called an amp stack.
- A head on one cabinet is a half stack.
- A head on two cabinets is a full stack.
The very first "Marshall stack" was an amp head on a single huge cabinet with eight 12-inch speakers! But that was too big to move easily. So, they changed it to an amp head on two cabinets, each with four 12-inch speakers. This made them easier to transport.
Many rock and metal bands use large arrays of speaker cabinets on stage. Sometimes, these are real working cabinets, but other times, they might just be empty cabinet fronts used for an impressive look!
Speaker cabinets come in many sizes. They can have one 12-inch speaker, four 10-inch speakers, or even eight 10-inch speakers. Bigger cabinets are often heavy, so they might have wheels and handles to help move them around.
Amp Cabinet Design
The wooden boxes that hold the speakers, whether in a combo amp or a separate speaker cabinet, are called cabinets. They come in different designs:
- Open back cabinets have a partially open back.
- Closed back cabinets are completely sealed boxes.
- Less common are bass reflex designs, which have a vent or port.
Most cabinets are made from plywood. Some cheaper models use MDF or particle board. The size, depth, materials, and how the cabinet is put together all affect the sound.
Sound Shaping: Distortion and Volume
Distortion is a special sound effect that many guitar amps can create. It's that fuzzy, crunchy, or aggressive tone you hear in rock and metal music. Unlike keyboard or bass amps, guitar amps are often designed to create this unique sound.
The amount of power an amp has (measured in watts) affects how loud it can get. But it's not a simple relationship. A 100-watt amp is only a little bit louder than a 50-watt amp to our ears. For bass instruments, you need much more power to make those deep, low-frequency sounds loud and clear. A bass player might need a 200-watt amp for a small club, while a guitarist could use a 50-watt amp.
Volume Controls
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Guitar amps have different knobs to control the sound:
- Volume on your guitar itself changes the signal coming from the pickups.
- Most amps have a preamp or gain control. Turning this up on an electric guitar amp often creates distortion.
- A master volume control sets the overall loudness of the amp.
- Tone controls like bass, mid, and treble let you adjust the brightness or depth of your sound.
By using these controls, guitarists can create a huge range of sounds, from a gentle, warm tone for blues to the extreme distortion used in heavy metal!
See also
- Vintage musical equipment
- Tube sound
- Bass amplifier
