What Is Gain on a Guitar Amp?

Gain is something you will often hear in the guitar world. Yet, even if that’s the case, not many can confidently answer what is gain on a guitar amp.

It is true that you do not need to know what it is to use an amp properly.

As long as you understand what happens when you turn the knob, you can get the sound that you want.

That said, knowing the basics of gain and distortion, as well as how they differ from volume, will allow you to appreciate amplifiers better.  

It can also help you choose the best amp the next time you’re in the market for one. 

How Do Amplifiers Work?

Before we talk about what gain is, it is important that you understand how amplifiers work first.

This way, you will have better insight into what is gain on a guitar amp.

Amplifiers have two main features: the preamp and the power amp.

Basically, the signal from your instrument goes through these two stages before the speaker emits the sound.

The Preamp Stage

When you pluck the strings of an electric guitar, it creates a signal.

However, this signal is not enough to make a big sound, so you need to plug the guitar into the amp.

The preamp is responsible for increasing the guitar’s low-level signal to line level. 

It is the minimum requirement for the sound to be recorded by audio equipment and typically ranges between 20 and 30 decibels.

While you can find external preamps, most are built into modern amps, so there’s no need to buy them separately.

Once the preamp intensifies the signal generated by the guitar, it sends this boosted signal to the power amp.

The Power Amp Stage

The power amp increases the standard signal level from the preamp even further. This will depend on the listener’s preference.

What happens is that it focuses on the intensity more than anything else, as the signal is already in its final form after the preamp.

What Is Gain on a Guitar Amp?

On most amps, you will find a knob that allows you to control how hard you push the preamp.

This control is most often called gain or drive in some models. You measure gain in terms of the ratio of the output and input levels.

If you encounter the term “Unity Gain,” it simply means that the ratio is 1:1.

Turning up the gain changes the shape of the signal, which then leads to distortion when a certain level is exceeded.

This threshold level is known as the clean headroom limit.

Beyond this point, increasing the gain will produce distortion instead of increasing the volume.

Just how much the signal is distorted will depend on how the guitarist will set up the amp.

Gain vs. Distortion

A lot of new guitarists confuse the terms gain and distortion, using one and the other interchangeably.

By now, you have some idea that gain is different from distortion.

Put simply, gain is the strength of the signal that goes to the preamp. Think of it as the input volume to the first stage. 

Keep in mind that increasing the gain does not automatically produce distortion.

If you keep it to a certain level, you can keep the sound clean, and doing so will boost the signal as if you were just controlling the volume.

However, if you drive the preamp past the threshold level, you can produce distortion and create interesting sounds.

In guitar world jargon, this process is known as getting “clipped.”

Many guitarists prefer the sound that this produces, as long as it is controlled.  

Most amps today have separate channels for clean sound and distortion. 

The clean channel has a gain that is less sensitive to clipping, whereas the distorted channel is much more sensitive.

Gain vs. Volume

As mentioned, increasing the gain increases the volume—that is, until you hit the clean headroom limit.

As you can imagine, this is a source of confusion for some people because they mistakenly believe that they are the same. 

In the same way that gain is different from distortion, it is also different from volume.

One key distinction between them is at what point of the signal chain they come in.

Gain cuts in at the early part before the signal enters the preamp.

It has some level of influence on the volume, but a whole lot more on the shape of the sound.

On the other hand, volume is controlled at the second stage of the amplifier, which is the power amp.

At this point, the tone of the signal is pretty much set.

It means that the only thing you can control is the intensity of the sound or the overall volume.

The level at which you can increase the volume will depend on the peak power of the amplifier’s speaker.

High Gain vs. Low Gain Amps

If you are shopping for your first amplifier, you would probably come across high gain and low gain amps.

A high gain amplifier is designed with a preamp that has a low clean headroom limit.

It will give you a heavily distorted or overdriven sound even if you set the volume low.

Additionally, adjusting the gain in this type of amplifier will control the distortion and not affect the volume in any way.

If you love playing heavy metal music with your guitar, this is an excellent option for you.

However, most high gain amps also come with an option for a clean channel to allow for more flexibility.

Basically, you’ll find that they have separate knobs for gain and master volume control.

In comparison, a low gain amplifier has a higher clean headroom limit. 

Hence, you can crank the gain up and increase the volume significantly without producing much distortion.

More often than not, it has high wattage and does not have a master volume control.

Is Gain or Distortion Bad?

The right amount of distortion can create a distinctive sound that many guitar players love.

However, too much of it can drown out the melody of the song and produce a mushy noise.

So, as long as you can control it, you can use distortion to your advantage.