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Beginners Guide to Using a Guitar Amp

Remember at school when you were shown how the various knobs and features of a guitar amp work? Me neither. You don’t want to be figuring this out on the fly when you turn up to your first jam, or when you’re trying out an amp in front of a pushy salesman. With that in mind, let’s have a bit of a tour around your average amp.

The Big Picture

Your guitar sound enters the amp at the input, gets shaped in the pre amp, and travels through any effects you may have in the effects loop. The power amp then takes that sound, makes it bigger and sends it to the speaker.

Sounds simple enough, but let’s take a look at how you can tweak that sound in each section of the amp.

Power on & Standby

It’s probably good practice to roll your volume down before turning your amp off, and make sure it’s still down before you turn it back on. I’m no amp tech, but the pop you get when you throw the power switch with the volume still up does not sound healthy for the amp. If nothing else, it’s a courtesy for everyone else in the room. Let’s face it, on a decent sized valve amp, that “pop” is more of a heart stopping “boom”.

As for standby, it’s largely debated as to whether there’s any point in using this feature. Most folks who know a thing or two about amps will tell you that this switch continues to be installed on amps as little more than a superstitious tradition. Having said that, if your manual tells you to leave your amp on stand by for a bit before using it, I don’t want to be the one to void your warranty.

Pre Amp

Inputs

If your amp has multiple inputs, you might be wondering which one you should be using, and why you need choices when it comes to simply plugging in.

On Fender amps with two inputs, one of these will be for pickups with a low output and the other for higher output pickups like humbuckers. When you see four inputs on a Marshall amp, these will be a high and low sensitivity input for each of its two channels.

Bright Switch

Some guitars’ pickups are darker sounding than others. To accommodate for this, some amps will have a bright switch near the input socket which will kick in a little more treble.

Gain

The gain knob controls the signal strength coming into the amp. While originally it may have been intended as another consideration to adjust for pickups with different output levels, the far more popular use of this knob is to turn it up until the signal clips with overdrive.

EQ

The eq section lets you adjust the tonal characteristics of your sound by tweaking certain frequencies or certain ranges of frequencies.

If you want to sound impressive playing on your own, use lots of bottom end while dropping your mid-range for clarity. If you want to be heard at all in a band setting, you’ll want to do the exact opposite. Check out this article about working with overdrive to learn more about setting eq and gain for audibility in a band setting.

Tweaking your low, middle, and high frequencies is a straight forward affair while you have three knobs which correspond with them. What happens when you only have low and high knobs?

It’s simple enough once you get used to an eq like this, but it can be a real hurdle for newcomers. Both of these knobs affect themselves and the mid-range at the same time. Here are a few examples of how they do this:

  • Low and high at halfway: mids are also at half way
  • Low and high cranked: mids are scooped (turned down)
  • Low and high turned down: mids are turned up

Multi-Channel Amps

On amps with more than one channel it’s not uncommon to find a row of gain and EQ knobs for each channel. It’s often the case that each separate channel is a separate pre amp circuit; although in some amps the second channel is actually just a higher gain setting with maybe a bit more treble. If that’s the case you probably won’t have much to tweak the second channel with.

There’s usually a footswitch you can connect to select which channel you want, but you might also find a switch on the amp that does the same thing.

Effects Loop

If your amp has an effects loop it’ll typically be on the back panel. To learn more about why you might want to use an effects loop, check out this article on pedal signal chain. Using the loop isn’t all that complicated. You plug a lead in from the “send” on your amp into the input of your pedal. The lead from the output of your pedal goes into the “return” of the loop on your amp.

Power amp

Master Volume

This one is pretty straight forward: it dictates how loud the power amp makes the signal before handing it to the speaker. I should clarify what’s happening here though.

Your power amp is actually always fully cranked, amplifying anything it’s given as much as it can. Much like how the gain knob controls how much signal comes into the pre amp, the master volume knob controls how much signal gets passed from the pre amp onto the power amp.

Presence

When you turn down the Master Volume, you might lose some of the high end from your tone. The Presence control is like a treble control for your power amp, allowing you to recover any lost top end once you turn the volume down.

Speaker Out

This is where you plug a lead from your amp to your speaker. It’s critical you don’t get this bit wrong. First of all, despite looking pretty much the same, instrument cables and speaker cables are different. Even though they both fit into these sockets, it’s important you only use speaker cables for this job, as using an instrument cable here could do damage. Plugging a speaker cable into your guitar would make it vulnerable to interference and noise.

The other thing to look out for here is making sure the amp impedance and speaker impedance match. I could (and probably should) write a whole post about speaker impedances and how to calculate the ohms for different combinations of speakers. For now though, just know that this requires caution. Don’t feel silly consulting your amp’s manual or asking for help from someone who knows about it.

One more caution about this part of the amp: if your amp is a valve amp, never turn it on without a speaker connected.

Dialling it all in

Quiet practice at home

Get the volume to a level you can work with, and then adjust the gain and eq to compensate for the overall reduction in sound. This is where the presence knob will come in handy.

With the volume knob on your guitar set to about half way, turn the gain on your amp up until it starts to break up, and then back it off a tiny bit. This will give you as much sustain and harmonic content as you can get while still having a clean tone. From there you can either use pedals for your drive sounds, use another channel in your amp, or simply roll your guitar’s volume up and hit the strings harder to push the amp into overdrive.

In a band setting

While the band is making a lot of noise, set your volume so you can hear yourself clearly. You won’t win a prize for being the loudest person in the room, and it’s pointless not having it loud enough for you and the rest of the band to hear.

Now adjust your gain as outlined above and set your eq to taste. It’s important to do all this while the band is playing at performance volume, as your audible frequencies are different in a band mix.

If you have the luxury of being able to play fairly loud, try this: Once you’ve got your clean sound dialled in with the pre amp gain at edge-of-break-up, turn the master volume up until the power amp starts to overdrive, then back it off just a little. Now when you push the amp into overdrive you’ll have both the pre amp and power amp breaking up. This is what people refer to as natural amp overdrive. If you only use the pre amp on its own for drive sounds, you’re missing out.

Classic Amp Sounds

While describing the tonal characteristics of an amp or pedal, people will often reference classic amp sounds. No doubt you’ve heard terms like “Fender cleans”, or “cranked Marshall” to describe how something sounds.

That’s not very helpful if you have no idea what they’re referring to. Hopefully we can fix that by having a look at the sort of sounds different classic amps are known for and why they sound the way they do.

Fender

In the early days overdrive was something to be avoided, so Fender aimed to make an amp that could get loud without breaking up. In the power amp they typically have a pair of 6L6 tubes, providing bucket loads of clean headroom.

6L6 Power Tubes

At low to mid volume levels they tend to have a scooped mid range. This emphasises the high and low end, making those clean tones sound big and smooth.

As you turn them up, more mid range starts to roll in. If you crank them all the way up, magic happens: When an amp that was designed not to break up is pushed so hard that it does, you get a glorious, massive sounding overdrive.

Tweed vs Black Panel

The sound outlined above probably best describes what is known as the black panel tone, or “blackface” to those for whom that phrase doesn’t primarily conjure up mental images of black and white minstrels. I’m not being “woke”, do an image search on “blackface” and let me know in the comments how many Fender amps you see.

We’re referring to the black control panel on the more modern Fender amps. Prior to this, Fender had their tweed range. These amps were far less powerful, and when turned up to stage levels would often start to overdrive. The tweed sound is associated with early gritty blues guitar sounds.

Marshall

Marshall’s first amps were an attempt to copy Fender’s offerings. Being made on a different continent meant that different components had to be utilised, and to accommodate those different parts, design changes were made.

Using EL34 tubes in the power amp meant they could be pushed into overdrive sooner. They also typically had much more mid range than a Fender.

EL34 Power Tube

They became notorious for their overdrive and mid-focussed tone, which made them an obvious choice for early rock guitar pioneers.

Hiwatt

When most people think of Hiwatt amplifiers, they think of ridiculous volume levels. These things are loud. They have the endless clean headroom of a Fender with an EQ curve somewhere closer to a Marshall.

Vox

These amps are best known for their top end response. You can hear this in the Beatles’ chimey, jangley clean tones, and Brian May’s treble focussed overdrive sounds in Queen. In the power amp they utilise EL84 tubes, which are a bit like EL34s but with less headroom. This means they’re often quieter and quicker to break up than a Marshall.

Vox AC30

EL84 Power Tubes

Orange

Think of Orange amplifiers as being like a Marshall only more so. They have more aggressive mid range and more gain on tap, allowing for heavy overdrive from the preamp section without having to crank the power amp into break up.

Mesa Boogie

The first ever Mesa amps were actually modded and re-badged Fender Princetons. They have a tonal response somewhere in the ball park of a Fender, but usually with many more features. The most common of those features would be a high gain channel.

The distortion sounds from the Dual Rectifier were pretty much the heavy metal standard from the early 90s to the late 00s.

“American Sound” vs “British Sound”

The big names on the American market were Fender and Mesa. Their sounds are typically high headroom and low mid range, with super sweet clean tones. Most people think of Vox and Marshall when they refer to the “British” sound, implying a more mid range to high end focus and earlier power amp break up.

The Brown Sound

This has nothing to do with the “brown note”, or the extreme low frequencies rumoured to cause fecal incontinence. It does however refer to a high gain guitar tone that has the potential to make rock guitarists shit themselves with excitement when they hear it.

Edward Van Halen used this term to describe his tone. In the early days, that tone was achieved by way of a Marshall Super Lead with everything turned all the way up. Where most rock guitarists were aiming to cut through the mix with plenty of mids and treble but little bottom end, Van Halen wanted a warmer sound that retained bottom end. I should note that over the years he used less and less mid range in his tone.

In general though, if someone refers to the “Brown Sound”, they’re probably talking about a high gain sound with a balanced EQ and the volume as loud as you’re prepared to push it.

Disclaimer

What I’ve described above are all gross generalisations. In this context though (making sense of buzz words like “British tone” or “Fender cleans”) generalisations can be helpful. It’s important to note that you can get two amps of the same model and have them sound different to each other. My goal here was not so much to help you choose which amp to buy, but to help you decipher marketing hype with music gear in general.

So what's this all about then?

Hi, my name is Andy, and I’m a gear-a-holic.

My early attempts to hide my shame from family and loved ones resulted in me buying low quality gear from questionable characters who definitely didn’t have my best interests at heart. I was a young guitarist with a fair idea of the sort of sound I wanted, and no idea how to get it. They don’t teach you this stuff in school, and sales staff in music shops are rarely going to present the facts as you need to hear them.

I’ve spent years of my life and thousands of dollars messing about with the wrong gear, and I know I’m not alone. It doesn’t have to be like this.

The aim of this blog is to share what I’ve learned and provide a few shortcuts for those just starting out on their journey. For many readers, a lot of what I write will seem completely obvious. Please bear in mind there are plenty of people who won’t find it obvious and may be too afraid to ask. These folks are my target audience.

I can’t stress enough that I’m not an expert. I’m not a professional touring musician and I’m nobody’s guitar tech. I’m just a guy on the internet who wants to help prevent others from making the same mistakes I’ve had to learn from. I’d like to encourage feedback in the comments section, especially if you feel something about my content is just plain wrong. We’re all here to share and learn, and I’ve yet to learn anything by being right. I only ask that you try to be nice about it.


Disclaimer:
My main motivation here is helping others understand the fundamentals of guitar sound, not making money. Having said that, there are costs associated with this, and it would be nuts not to (at least to some extent) monetise the site. To that end you’ll see some ads here and there, and affiliate links to sites where you can buy some of the gear I mention.

Buying gear through those links won’t cost you any extra, but the site in question will throw me some chump change for directing traffic to them. On that note, Amazon.com requires me to state this: “As an Amazon Associate I earn from qualifying purchases.”