Amps are the most crucial element in the sound of modern electric guitar-based music. More so than guitar pedals, and possibly even the guitar itself, the amp is where the sound finally outputs. Knowing and understanding the many types is an essential factor in becoming a well-rounded musician.
In this guide, we’re going to provide a decent grounding in how to understand the many different ones available. Let’s get to it.
Table of Contents
What is a Guitar Amp?
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 an audible level.
Amps add their own distinct tone too. The tone from an acoustic guitar comes from its shape, size, and the type of wood used in its construction. The same goes for amplifiers – and this is why metalheads prefer some, and jazz players love others.
While there are numerous types, in essence, they all do the same thing: when you pluck a string, a series of magnets (called pickups) positioned underneath the strings converts the motion into an electric current. This current is passed along a wire into the amp, which amplifies the signal, and then passed along to a speaker.
Types of Guitar Amp
Let’s now look at the different types.
- Solid-State / Transistor
- Tube / Vacuum
Solid-State / Transistor
Solid-state or ‘transistor’ amps are generally more dependable since they utilize transistors in place of tubes. The signal never changes and has no possibility of overloading the amp, resulting in them being 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.
The sound of these lacks a lot of the unique character found in tube amps, but they are still hugely popular and the preferred option for many guitarists such as the band Radiohead’s guitarist Jonny Greenwood who plays a Solid-State Fender Eighty-Five, as well as John Fogerty and Andy Summers, among many others.
Tube / Valve Amps
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, and they are often described as being “warmer” and more “authentic.” They also add a certain ‘color’ to the tone.
The other thing you’ll want to be aware of is ‘headroom.’ As the level of the electronic signal that enters the 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 they have a particular volume and gain at which everything will begin to sound muddier. Which is by no means a bad thing. Metal, blues and rock music were built on this.
Another type worth knowing about is called a modeling amp – these use computer circuitry to programmatically emulate the sound of some of the most famous and recognizable amps in the world. They’re lighter, more reliable – and if shop around, the best modeling amps sound almost as good as the real thing.
There’s a number of features that make an amplifier perfect for using for practice.
For a start, they are more often not only small in size (some are micro) they’re low in power too (as low as 1 watt). An amp like the Roland Micro Cube GX (which many argue is the best practice amp available at that price range) has handy features such as a socket for guitar headphones, onboard effects so you don’t need to bother with pedals, battery power, and various other features.
Along with being either solid-state or tube designs, they can also be separated by their capabilities.
Combo amps have everything you need built into one box – including the controls for volume, gain and EQ, any built-in effects like overdrive or reverb, inputs and outputs for effects pedals, amplification circuitry and at least one or two speakers.
They are great for playing at home or small gigs which don’t need excessive levels of volume. Bigger venues will require more wattage, that’s where ‘head’ units come into play.
Unlike the combo variety, head amps don’t include speakers – the only thing they do is amplify your signal, meaning you can hook up as many speakers (called ‘speaker cabinets’ or ‘cabs’) as you like. This lets you use the same device to cover an entire range of venues, from smaller gigs up to the biggest arena. All you need to do is choose which speakers you’re going to connect it to.
Now we’ll look at some common settings found on these devices.
Inputs and Outputs
You’ll see at least one jack on the main panel of your amp, which is where you plug in your guitar. Outputs might be on the back 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. However, they’re not. Gain and volume increase the strength of your signal in different ways:
- Volume is what you’d expect it to be. The higher the setting, the louder your guitar sounds.
- Rather than adjusting the number 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 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.
Many amps have more than one channel. You typically find a ‘clean’ one which will give you a non-distorted sound, as well as an overdriven channel, often referred to as ‘dirty’ because of its distorted sound. Each channel will typically have its 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.
Sound is broken into low/bass, mid and high/treble frequencies. These controls let you place more emphasis on each of those sections – sounds simple enough, but different combinations can result in amazing differences in sound.
The only thing that tends to vary here is 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.
Presets and Modeling
Some devices will do most of the work for you, and allow you to switch between dozens of combinations to create specific sounds, which can then be further adjusted with the onboard controls.
This is great if you don’t want to spend hours and hours tweaking each dial-in turn, and 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.
Imagine for a moment you buy a 100 watt Marshall stack from a friend after hearing it at a gig. It sounded amazing in the club, but once home you try playing it and realize to get the best sound from it, you have to play it at ear-shatteringly loud volumes (i.e. you’d have to ‘drive’ or ‘cook’ the tubes to get them to overdrive).
This is where an amp attenuator comes in useful. These gadgets, no bigger than the size of your average guitar pedal, absorb the excess sound into heat and let you cook your valves at low volume. You get your natural overdrive at low volume, the neighbors don’t call the police. It’s a win-win 🙂
So there you have it. As you’ve seen there are plenty of types of amplifiers out there. In this article, we’ve focused on guitar-based ones, but remember keyboard amps are incredibly versatile too.