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Guitar amps are fascinating: so many models, each with a unique tone. But getting the tone in your head into the amp isn’t that easy; some amps just aren’t meant for those types of tones.
So if you’re wondering how guitar amps work, I’ve made this guide for you. I’ve explained everything below, from all the types of amps to the science behind them, how they influence tone, and what you need to look out for.
What Does a Guitar Amp Really Do?
A guitar amplifier takes your electric guitar’s signal and multiplies it to become louder. It outputs this sound through a speaker cabinet, so you can easily hear what you’re playing. Amps work on different technologies like tubes, transistors, and digital circuits, which change the tonality of your guitar.
There are a lot of different guitar amps with different features, but the basics remain the same: they’ll make your guitar louder. But still, if you want to get the best tone from your guitar and emulate some of your favorite musicians, you’ll need the right type of amp.
Amps come in several different wattages and sizes, with different controls and effects. So keep reading to see all the types of amps you’ll likely come across and what you should look out for.
Types of Amps and How They Work
Guitar amps are not one-size-fits-all. There are several kinds of amps with different technologies that sound unique and change your guitar tone.
1. Tube Amplifiers
These were the first amps to be made, way back in the early 1900s. Technology depended mostly on vacuum tubes back then, and amplifiers were no different. Vacuum tubes have an excellent track record when it comes to audio signal amplification and modification.
What’s impressive is that despite newer advancements in amplifier technology, tube amps still remain some of the best-sounding amplifiers, making your guitar sound rich and warm in tone.
A vacuum tube, as the name would suggest, is a tube with a complete vacuum on the inside that is fitted with electrodes. The vacuum inside the tube allows electrons to flow freely, which they cannot do in the air. It’s this flow of electrons that is used to amplify the signal.
How does a vacuum tube amplify and modify sound?
Four components inside the vacuum tube do most of the heavy lifting:
- The cathode is the positively charged pole emitting a stream of electrons in the presence of a negatively charged pole.
- The anode is the negative pole attracting electrons from the cathode. The anode also picks up the signals from your guitar.
- A heating filament. This heats the cathode so that the electrons can flow freely.
- A grid, placed between the plate and the cathode, which is connected to your guitar input. The grid charges the input and gives it a slight positive or negative charge. The grid is the reason behind signal amplification.
When you play your guitar, a slight voltage forms across the grid because of the input from your guitar. This voltage fluctuates according to the sound signals coming from what you’re playing. This signal collects electrons from the anode onto the plate, and these electrons become amplified signals.
The way the electrons interact inside the tube also creates natural harmonics, giving tube amps their signature special sound. The entire system is analog here, so there’s very little loss of signal strength or quality.
Tube amps produce great sound with increased bass and midrange, and if you’re someone who likes distortion in their music, an overloaded tube amp is usually your best bet. They’re perfect for heavier genres like Rock since they can get very loud without compromising on sound.
However, tube amplifiers are fragile because of how delicate their components are. It pays off to know some of the technical knowledge behind your amp, since they’re finicky with a bad setup.
Using it improperly can cause damage to your amp and even blow the vacuum tubes. If you’ve got one of these amps, take good care of them, since it’s difficult to find spare parts and repair can cause a significant dent in your wallet.
There are several great tube amps from the likes of Marshall, Mesa Boogie, Vox, etc. Some of the most common vacuum tubes seen inside these are the 12AX7, 6V6, KT66, etc. If you’re planning to buy one, definitely try and test one at a local shop.
2. Solid-State Amplifiers
Solid-state amps were created after tube amps, and they use transistors to amplify and convert electric signals into audio waves. The name “solid-state” comes from the semiconductor circuits which are present inside these amplifiers. They’re not as fragile as vacuum tubes.
These were crafted as an alternative to heavy and fussy tube amps, which were difficult for beginner guitarists to use. Most practice amps and low-range amps available in the market now are solid-state amplifiers.
In a solid-state amp, the input from your electric guitar passes through a circuit board, which amplifies the signal before sending it to the speakers. Because these amplifiers do not come with glass tubes like tube amplifiers, they are portable and durable.
Unlike tube amps, which distort at high and low frequencies, solid-state amps produce a similar tone and range of sound across a large bandwidth. This is because of the transistor within the amp, which can tolerate a greater range of input than vacuum tubes.
Without going into too much technical detail, solid-state amps work with the principle that a small change in the input voltage would lead to a large change in the output voltage. Since transistors require very little voltage to work, solid-state amps also use much less power than tube amps, so they’re also more eco-friendly.
While solid-state amps can get distortion quite easily, the tonality is very different from tubes. They don’t have the rich warmth or natural harmonics that tube amps produce. The ‘saturation’ point is much lower, so you achieve high gain at lower volumes.
What this means is that you’re not likely to get a classic rock tone like Slash or David Gilmour with a solid-state amp, but you’ll still get a good sound. Especially if you combine it with some good pedals.
3. Hybrid Amplifiers
A hybrid amp essentially refers to any amplifier which uses a combination of various technologies to produce and amplify sound waves. In practice, a hybrid amp is usually one with both vacuum tubes and solid-state transistors.
Hybrid amplifiers generally use tubes in the pre-amp (voltage amplification) stage, and solid-state devices like transistors in the output stage. These amplifiers keep the warm and rich sound from tube amps, but require less power to operate.
The tubes used in the pre-amp stage allow the amplifier to produce the natural harmonics and distortion which many want from tube amps, while the transistors used for output ensure that you get consistent signal strength with high volume.
Let’s see a step-by-step breakdown of how hybrid amplifiers produce sound:
- The pre-amp is where the gain is applied to the sound. Since hybrids use vacuum tubes here, you get a rich, smooth gain similar to tube amps, with a lot of harmonics and warmth to the sound.
- The tone controls on a hybrid amplifier allow you to monitor and fine-tune the frequencies going into your amp. There are usually three controls, one each for bass, mid and treble frequencies, just like classic amps.
- Next, the power-amp stage is made using transistors. This is where the ‘Volume’ knob increases output and signal strength without affecting the tone too much. This stage has lower noise and better output consistency due to transistors.
- At the speaker, the electrical signal is converted into audio waves, which you and your audience can hear.
A hybrid amp like the Orange Micro Terror is a good choice when you want the best of both worlds: a rich tube sound with the ease and consistency of solid-state amps. But with newer tech, even hybrid amps are losing out on popularity.
4. Digital Amplifiers
Digital amps are one of the newest innovations to hit the sound industry, and they work using Digital Signal Processing (DSP).
The analog input which is received from the guitar is converted into a digital signal (binary, 0 and 1). This is in the form of a linear pulse code format, which is modified into Pulse Width Modulation which is processed by the amp.
The amplifying devices in these amps are still transistors and microchips, but they function as electronic switches which change the analog signal from your guitar into digital signals.
These amplifiers are highly efficient and don’t heat up even when you’ve been working through a long jam session. This also makes them more compact and light, which is ideal if you need a portable amplifier. The tech is so portable, that even mobile apps can work as digital amps.
How digital amplifiers create sound
To simplify, here’s what’s happening:
- In the input stage, the analog guitar signal enters the amplifier, where it is converted into a digital signal using an analog-to-digital converter.
- Once the amplifier has a digital signal, Digital Signal Processing (DSP) algorithms take over. These DSP algorithms can produce various tones and effects as per your needs.
- This stage is the reason why digital amplifiers can replicate the sound of classic tube amplifiers, while also adding delay, reverb, or distortion.
- Once the DSP algorithms process the sound, a solid-state power amplifier multiplies these signals to make it louder. This is necessary to drive the signal into the speaker.
- The speaker in a digital amplifier converts the digital signal into sound waves.
The full flexibility of digital amps is truly seen in modeling amps, as discussed below.
5. Modeling Amplifiers
Modeling amps are a subsection of digital amplifiers, designed to emulate and ‘model’ any amp or signal chain you want. They use AI, neural networks, and a host of tech to mimic the tonal characteristics of any amp.
This is seen in high-end pedals like the Kemper Profiler and the Neural DSP Quad Cortex, as well as software plugins like BIAS FX 2 and AmpliTube.
What you can do with these is give them an input signal, say one of your favorite guitar amps, and it will emulate the signal nearly perfectly. You can then just carry your pedal (or a laptop) and get the same tone from that.
This is incredibly convenient compared to lugging around heavy amps and pedalboards. So if you’re a gigging musician (or plan to be one), then this is an excellent alternative. You can easily create a big library of tones and carry them around.
Even if you don’t have physical gear yourself that you’d like to ‘model’, the internet and cloud storage has made it easy for musicians to share tones with each other.
So if you have a modeling amp that connects to the internet, you can just download patches and get the exact tone you need.
How to Choose an Amp When Playing Guitar
The kind of guitar you have and the sort of music you play will largely influence the kind of amp you need to use. So here’s a breakdown of what you need to look out for when choosing an amp for yourself, whether for practice, recording, or live performances.
Because so many types of amps exist, it can be difficult for beginners to decide which one to get. However, the choice boils down to what you play, and what you’re looking for when it comes to the sound and response from your amp.
Tube amps have a natural sound quality that is difficult to imitate or find in other kinds of amps. They’re popular amongst musicians from “heavier” genres like metal or rock, but they’re also a surprise hit with jazz musicians.
They tend to be more expensive than solid-state amps, but they are worth the investment if you’re looking for impeccable tone and do not mind sacrificing portability. Tube amps are the perfect choice for recording, although modeling amps are much easier to work with.
Solid-state amps are the most commonly found beginner and practice amps. They’re known for their reliability, durability, and low-maintenance setup. If you’re on a tight budget, this is the amp for you. Solid-state amps offer a clean and crisp sound without much distortion, which is perfect for alternative, punk, and pop guitarists.
A hybrid amp combines the best of both worlds by offering the richness of a tube amp and the affordability and reliability of a solid-state amp. Their sound is perfectly suited for genres like heavy metal and hard rock.
While they don’t exactly replicate the sound of a tube amp, they make up for it through durability and ease of use. Just like a tube amp, though, remember not to knock around a hybrid amplifier too much, since the glass tubes inside them can get damaged and even blown out.
Digital and modeling amps are versatile and portable. They can be a significant investment, but you can also get great tones from lower-end models. Whether a multi-fx pedal, a plugin, or a combo amp, all are good choices.
These amps replicate the sounds of various amps, effects, and pedals, making them the perfect choice for a guitarist delving into several genres at once. The one advantage of investing in a modeling amp is that it negates the need to buy different pedals and amps. You can carry a range of tones with just one device.
The wattage of an amplifier that suits you will depend on several factors, including your playing style, genre, and budget. However, as a general rule of thumb, amplifiers with higher gain and wattage are suited for large venues, while amplifiers with less wattage are for smaller audiences and rooms.
Practice amps come within 3-10 watts, and they’re great for use at home, rehearsals, and in small rooms of people. These amps are usually lightweight and portable, with a decent low-volume sound. You’ll mostly find solid-state amps at this wattage, and they’ll be on the lower end of the price range as well.
10-50W amps are suitable for medium-sized venues, coffee shops, small auditoriums, and large recording rooms with several other musicians. These amps offer more volume than practice amps and are a little heavier and bigger.
This range is great if you’d like something you can practice with, but also perform with.
If you’re a heavy metal musician, or you play other similarly loud genres, you will need a high-gain amp. These amps operate above 100 watts, and they’ll provide you with the aggressive sound which your genre requires.
They’re perfect for large clubs, outdoor festivals or street musicians, and large theatres. While they are more expensive than lower-wattage amps, they offer powerful and loud sound without compromising on tone.
But it’s important to know that you need to make sure your speakers match your amp’s wattage and impedance. Both these values need to be compatible, else you risk damaging both amp and speaker.
The amplifier you’ve plugged your guitar into heavily influences the tone of the sound produced. The construction of the amplifier itself determines the audio wave it eventually gives as output, which is why there’s such a difference in tone between the various kinds of guitar amps available in the market.
Tube amps have a warm tone, distorting and intensifying sound very easily. They’re largely regarded as the gold standard for guitar tones, and combining them with analog pedals can make them even better.
If you need an amp with good drive, dynamics, and power, tube amps should be the one for you. However, keep in mind that tube amps are expensive, heavy, and high maintenance. Plus, they don’t always have a good tone at low volume levels, because the tube needs to be driven.
Solid-state amps aren’t really known for their tone, since they have less reactive distortion than tube amps, but they do have a very reliable clean sound which is perfect for softer styles of music like Soul and R&B.
These amps work well even at lower volumes, which is why solid-state amps are perfect if you practice or want to play for a tight-knit audience.
Hybrid amps offer a similar range of sounds as tube amps, but because they still rely on a half-analog half-digital means of creating sound, there is some compromise on quality.
Most guitarists using hybrid amps are recording musicians, and these amps are great for just about any style of music. So long as you don’t need the exact same sound from a tube amp, a hybrid amp should do the job well enough.
Modeling amps allow the most choice when it comes to tone. They offer multiple presets, effects, and pedal styles, and they can quite faithfully emulate several kinds of amps. Regardless of which genre you play, a modeling amp would come in handy.
Through constant redesigning and innovation, the modeling amps which are currently available on the market can mimic different effects and amps well enough – an untrained ear would not be able to tell the difference.
4. FX and Features
Finally, look at other features you get with the amp, including reverb, delay, compression, and other effects. Will you be using it with a pedalboard? Or do you want the amp to have everything you need?
Some amps nowadays even have extra practice features, like in-built backing tracks, Bluetooth connectivity, mobile apps to control them, and so much more. This can make them more convenient to use.
For this, always think about your current and future setup, and see what fits best into the signal chain. If you’re playing live, consider size and weight options too. You’ll want an amp that can easily be transported without compromising on sound or performance quality.
Check our article on How To Mic A Guitar Amp.
Is a guitar amp just a speaker?
What makes guitar amps sound different?
Do you really need an amp for electric guitar?
I trust that this helped you understand how your existing guitar amps work, and how you can choose when buying a new one. Don’t get intimidated by the science of it: just focus on the tonality and choose what sounds best to your ears, while being convenient to use.
If this guide helped you, don’t hesitate to share it with fellow tone geeks and send in any queries or suggestions.