Guitar amps are usually the next big ticket item you buy after your guitar. But trying to navigate your way around all the types of guitar amps can be a nightmare. So here's our ultimate guide to guitar amps. Enjoy.
- What are guitar amps, how they work and why you need one
- Solid State vs Vacuum Tubes
- Combo Vs Head Amps
- Inputs And Outputs
- Gain And Volume
- Presets And Modelling
What are guitar amps, how they work and why you need one
If you plugged your guitar straight into a speaker and started playing you wouldn’t hear much, even if the volume was turned all the way up. It’s the amplifier’s job to boost the signal to a high enough level that everybody in the audience is able to hear it. This boosted signal is then sent to a speaker, and everybody can hear it.
Amps also change the tone of the sound a great deal. With acoustic guitars this is done by shape, materials and size. This also has some impact with electric guitars, but it is far less noticeable. This is why some amps are preferred by metal guitarists, and others are loved by jazz players.
Guitar amps can be categorized in a few different ways. The common thread shared by all of them is what they do. When you pluck a guitar string on an electric guitar, a series of magnets called the pickups positioned underneath the strings converts the motion into an electric current. This current is passed along a wire into the guitar amp, which amplifies the signal. This signal is then passed along to the speakers, which may be built directly into the guitar amp.
A similar process happens with electro-acoustic guitars, although the actual mechanics of how the signal is created can vary slightly with the type of pickups used. The result is more or less the same, with some minor differences - although that’s beyond the scope of this guide.
Guitar amps can be broken down into a few categories. They can be driven by solid state electronics or vacuum tubes. They can be either head or combo amps. Finally, they can also be grouped by power (wattage).
Solid State vs Vacuum Tubes
Solid state guitar amps run on the same sort of technology that most of our world does. The signal from the guitar is fed into a digital system of electronic circuitry. If you’re familiar with the circuit boards you’d find inside computers, laptops and digital alarm clocks, you’ll notice that they have the same sort of thing in solid state guitar amps.
Vacuum tube amps are the original breed. Instead of converting electrical signals into a series of binary values, the strength of the electric signal is what matters. This gives the inner workings of these kind of amps a very organic feel. In fact, they are often described as being “warmer” and more “authentic”.
We could spend all day talking about the various components, but that wouldn’t bring you any closer to understanding how they sound, would it?
To understand why these two types of guitar amps sound different, you need to know just a little bit about why they work the way they do.
When you play guitar through a solid state amp, the signal is artificially increased in strength. The signal never changes, and has no possibility of overloading the amp. This means they’re cheaper and easier to maintain, as the only real damage you’re likely to do is blow out the speaker if you insist on playing metal with all of the settings cranked up to the max every day. The sound of these amps lacks a lot of the unique character found in tube amps, but they are reliable.
Tube amps operate almost completely differently. They can be thought of as an extension to the instrument. Increasing volume, in layman’s terms, is a case of allowing more of the signal to pass through the circuit unhindered.
It’s difficult to explain what effect this has on the sound of a guitar being played with words alone. There are two things you should know though.
- Firstly, a tube amp will impart a certain ‘colour’ to the tone, making it sound noticeably different to any other amp. Although within the same model there is little enough variation they can be reliably identified by this tone colouring alone by expert ears.
- The second thing you’ll want to be aware of is ‘headroom’. As the level of the electronic signal that enters the vacuum tubes increases, so does the level of the distortion in the sound output. Up to a certain point the tone remains clear, and each frequency can be picked out easily. This means that vacuum tube guitar amps have a certain volume and gain at which everything will begin to sound muddier. This is by no means a bad thing. For example, metal, blues and rock music was built on this.
If you want to buy your own tube amp, we’ve already put together a selection of some of the best ones money can buy here:
Combo Vs Head Amps
Along with being either solid state or vacuum tube designs, guitar amps can also be separated by what capabilities they have.
Some guitar amps have literally everything you need built into one box. This includes the controls for volume, gain and EQ, along with any others such as built-in effects like overdrive or reverb. You’ll also have all of your inputs and outputs for effects pedals, additional speakers or headphones as well as the guitar itself of course. There will be the amplification circuitry and also at least one or two speakers.
If you wanted to start playing guitar immediately, all you’d have to do is turn it on, plug your guitar in and start playing. Small combo amps are great for bedroom practice, and larger ones are great for lots of gigs in smaller venues such as coffee shops, bars and can do a decent job in most indoor places.
Head amps are slightly different. Unlike combo amps, they don’t have any speakers at all. The only thing they do is amplify your guitar signal. So if that’s all they do, why on earth would you want one?
It’s a very personal choice, but here’s what it boils down to. If you need raw sonic power, you need to defeat Dr. Robotn- wait that’s not right. What I meant to say is, you can hook up as many speaker cabinets of any size as you need to a head amp. This lets you use the same amp to cover an entire range of venues, from your bedroom practice all the way up to the biggest arena. All you need to do is choose which speakers you’re going to connect it to.
We’ve mentioned that different amps can be better suited to different sized venues. At this point it’d be fair for you to be under the impression that this is solely dictated by the amount of speakers you have.
This is a big part of the story, but it’s not the whole tale. You also need to look at how powerful the amplifier itself is.
The smallest tend to be somewhere between 10 and 20 watts. These are great for practicing at home, and can be useful for live performances if you’re going to be plugged into a PA system anyway. On the opposite end of the spectrum we find those 100 watt stacks that every rockstar we’ve ever heard of plays exclusively.
You could have the world’s largest array of speakers, but you’re not going to have the true face-melting effect you’re after unless you have an equally powerful amplifier to go with it.
The best way to know how many watts you need is to look at the types of places you’re usually playing in. As long as you can ‘fill the room’, you’re good.
Another thing you’ll want to keep in mind is at what point the clean signal (headroom) is going to be lost and be replaced with the more distorted tone if you’re using a tube amp. Amps with a higher wattage can handle a lot more noise before it starts to break up, so if you need a lot of headroom a higher watt amp can actually be better in a small venue.
It’s also important to keep in mind that not all amps are equal. Headroom can vary wildly between different models of the same watt rating. The key to finding the right one for your needs is to experiment endlessly. Go down to your local music shop and try out many different amps. Listening to examples that have been recorded by other people really isn’t going to help in this situation.
Which amp for me?
Even with everything we’ve talked about so far, you might still be struggling to decide on the type of guitar amp you need.
A few factors are going to influence your decision here, so we’ll take a look at each in turn.
If you’re a beginner guitarist, there’s no need for you to run out and buy a huge head amp and speaker stack just because it’s what the greats used. A good amp won’t make you any better of a player. In the early days when the only person listening to you play is yourself, all you’re going to want is something cheap that doesn’t make you sound worse than you actually are.
In this situation I’d recommend a solid-state combo amp of no more than 20 watts.
Let’s say you’ve gotten a little bit better and you’re wanting to experiment with different types of sounds. You might have a few effects pedals and the like, and perhaps you’re thinking it’s time to upgrade your guitar amp as well.
We haven’t talked about these before, but you can also find ‘modelling amps’. These let you emulate the sound of some of the most famous and recognisable amps in the world. They’re great for when you want to sound like another guitarist, but don’t have the budget to go out and buy hundreds of different amps. All you have to do is buy a modelling amp and flick through the different options until you find the one you want.
You’re probably playing a few gigs at this stage. Here you’ll find having a higher watt amp, around the 40 to 50 mark, will be more useful. This will let you comfortably play in a range of different venue sizes without exploding your ear drums trying to break out of a clean tone.
Past this point you’ll know what you want to sound like. Your best bet will be to buy a head amp and speaker cabinets separately.
Money makes the world go round, not music. How much money you have available to drop on a guitar amp is probably going to be the biggest deciding factor unless you’ve got a lot of money to spare.
Hybrid and modelling amps are great here because they give you a lot of options at once, potentially saving you a great deal of money later down the line. Buying a higher watt amp at first will also let you go from practicing to performing without extra investment, although if you’re a complete beginner this is a bit of a gamble as you might never actually get to the point where you want to perform in public.
Solid state amps are also a lot cheaper. Tube amps use much older technology that are prone to needing repairs and replacement parts. Some of these can be viciously difficult to actually find, and can cost as much as a new amp by themselves. It’s true that they sound beautiful, but they’re also very high maintenance.
Despite that, there are some very affordable tube amps out there if you know where to look.
The guitar amp you need for playing thrash metal is going to be very different to the one you need for playing rockabilly.
That’s not to say that a 100 watt Marshall amp is going to refuse to make any noise if you try to play classical music through it. That would be hilarious, but also very pointless.
The truth is that whilst you’re starting out, you won’t really notice the difference between amps apart from volume and extreme differences in tone. If that’s where you’re at, just get something cheap and reliable.
But let’s say you’re regularly performing gigs. Perhaps you’re recording some material for the first time. You want to sound as good as possible, so let’s take a closer look at some different genres of music and what qualities you’ll want to look for in your amps.
For this type of music it’s all about the tone. The amp needs to be able to roar, even if you haven’t cranked everything up because you’re playing in a bar. Features you’ll be looking for here are a good balance between clean and dirty tones so you can intersperse a wall of noise with a clean breakdown or the option to switch between multiple channels.
A higher watt amp than would normally be warranted is also better here, because the general level of volume you’re aiming for is only slightly below ‘lethal’.
If you’re prepared to spend a lot of money on replacement parts, a tube amp would definitely be the better option here. However, if you’re budget conscious then you’ll be doing everybody a favour by going with either a hybrid digital amp or a solid state one.
Plenty of people like to say how solid state amps are completely inferior, but a lot of this comes from the early days when they weren’t so great. Newer solid state amps can sound remarkably good, and the huge range of effects pedals and EQ options you can choose from these days means that the cold synthetic sound often attributed to solid state amps is by no means the only sound you can get from them.
Jazz, Blues And Rock n Roll
Tube amps are king for all of these genres of music. It might seem like the three don’t have a huge amount in common, but they’re all building from the same foundations.
Generally speaking, older styles of guitar music pair very well with tube amps, simply because you get a much better tone to the sound. Additionally, since you can usually get away with playing at a slightly lower volume than compared to contemporary metal and rock genres, you’re also much less likely to blow out the vacuum tubes.
Of course, there are other concerns here. Blues and rock music is rarely played with a perfectly clean tone, so you’ll want to be able to break out of that fairly easily.
If you’re going to be a doing a lot of cover songs, we strongly recommend getting a modelling amp. It’s barely different from using the original amps the settings are based on, and if you want your audience to have an experience as close to the original as possible, this is going to be both the cheapest and the easiest way of doing this by far.
If you’re playing an electro-acoustic guitar or a mic’d up acoustic, and want to retain the acoustic character of your guitar, you’ll need to approach your selection for guitar amps very differently.
Having very high headroom is absolutely critical here. You do not under any circumstances, barring a few highly individual stylistic choices, want to have any distortion whatsoever. A clean tone with minimal colouration is what you’re aiming for.
To this end, many amps have been made specifically for acoustic use.
A couple of features specific to these are anti-feedback controls that reduce unwanted noise, and you may also find that there are different types of inputs so that you can hook up both a guitar and microphone so you can use it for vocals as well.
Some built-in effects like chorus and reverb can also be great features, especially if you can’t connect to your effects pedals before the amplifier itself.
Knobs, dials and oh, my!
If you’re not particularly familiar with guitar amps, the range of controls some of them possess can be a little intimidating. It’d be nice if they had a button that said “metal” and another that said “rock”, but that wouldn’t give you a whole lot of control now, would it?
So let’s make sure you have a thorough understanding of what some of the most common settings you’ll find do.
Inputs And Outputs
You’ll see at least one jack on the main panel of your amp. This is where you plug in your guitar. Outputs might be on the back. This is for connecting to speakers or headphones. There might also be an XLR jack for connecting a microphone, and a 3.5mm input for connecting a portable device like a phone or something else that can play a backing track for you.
Gain And Volume
At first these might seem like the same thing. They both increase the signal of your guitar, but in different ways. Volume is exactly what you’d expect it to be. The higher this setting, the louder your guitar sounds.
Gain is slightly different. Rather than adjusting amount of decibels, gain impacts the tone. The higher the gain the less ‘clear’ the sound will be. Higher gain is found in heavier styles of music, but moderate amounts are used whenever a perfectly clean tone isn’t desirable. This setting can take you all the way from muddy blues to face-melting metal.
If you don’t see a ‘gain’ setting, you’ll probably see something called ‘drive’ instead. Don’t worry, it’s the same thing.
Some amps have more than one channel, typically a ‘clean’ and ‘dirty’ combination is used, although the labels may vary slightly. These will have their own gain and volume controls. These are perfect for when you need to switch rapidly between high and low levels of distortion, as doing so is usually no bigger task than pressing a button or using a stompbox.
If your guitar amp only has one channel, you can work around this by using the gain knob on your actual guitar. This will let you roll off the gain quickly as you need to without having to fiddle around.
This is one of the more esoteric parts of a guitar amp that beginners don’t fully understand. Sound is broken into low/bass, mid and high/treble frequencies. These controls let you place more emphasis on each of those sections. This is simple enough, but different combinations can result in amazing differences in sound. For example, by manipulating these settings you can make your guitar sound like it’s gradually emerging from underwater.
Pretty cool, huh?
The only thing that tends to vary here are whether each channel (if there is more than one) has its own EQ controls, and the mid control might be replaced with a contour control. If that’s the case, it doesn’t control the strength of the mid frequencies so much as what is defined as a middle frequency. This is a subtle, but important difference, as it will change what range of frequencies are affected by the other two.
On cheaper practice amps, it’s also worth noting that there might not actually be any EQ controls.
Presets And Modelling
Some amps will do most of the work for you, and allow you to switch between dozens of combinations to create specific sounds, and these can then be adjusted with the individual controls.
This is great if you don’t want to spend hours and hours tweaking each dial in turn, and just want a quick ‘metal’ sound or an easy way to sound like Hendrix. These presets tend to have rather creative names that give you a rough indication of what they sound like.
If you have a modelling amp, you’ll also be able to choose between which amp you want to emulate the sound of. How accurate this emulation is and which options you have available will depend on your amp, so it’s impossible to go into any more detail without mentioning specific modelling amps.
What Settings Should I Use?
I know you’re eager to start using your amp, and you’d love a quick guide on how to create a specific sort of sound.
Unfortunately, that can’t really be done. There is so much variation between amps that if you set a dozen different amps to the exact same settings, you’ll have a remarkable level of variation between how they actually sound in the end.
So instead of giving you a bunch of specific numbers, I’d like to share some general guidelines instead.
For Clean Tones
If you’re using a tube amp, roll the volume back as well. If you need more volume, change your speaker setup. If you have EQ controls, keep them all in the middle, or perhaps slightly lower. If you’re after a nice driving bass line you might want to decrease everything else in relation to the bass ever so slightly.
This is a time for playing with the EQ as well. If you’ve got a thin sound, it’s generally a case of having too much treble and not enough mid. If you’re sounding muddy, you’ve got too much gain and bass.
If you’re not using a combo amp make sure you’ve got the right balance of speaker types. Unfortunately that’s a whole topic in itself, so we can’t get into it too much here. However, with the right settings you’d be amazed at what you can make a couple of six inch speakers do.
For Dirty Tones
These can cover a massive range of sounds. This could be quite subtle or extremely in-your-face.
The higher they both are, the closer you’ll get to the sound of metal. Lower amounts are perfect for blues. Somewhere in the middle is your alternative or rock sound. The specifics on where you’ll go really depends on how heavy you want to be.
If you're mixing these tones on extreme ends of the scale, you’ll absolutely want an amp with multiple channels.
Ged is Founder and Editor-in-chief at Zing Instruments. He’s a guitarist for London based gypsy jazz band ‘Djangology’ and when he’s not ripping up and down the fretboard, he’s tinkering with his Campervan.