Differences Between Gain and Volume Explained

Have you ever used a guitar amplifier, a mixing console, or even an audio interface? You have most likely come across controls called gain and volume. These controls have been found on music gear for a very long time. Yet there is still great confusion around them.

Gain is the change made to an electrical signal to alter the intensity. Volume is the output level from a device that provides loudness. While they might look the same, they are quite different.

Knowing what they do and how they differ can make a huge improvement to your overall sound! Have you ever found yourself wondering what those gain controls really do? Let’s dig in and find out how gain and volume are different!

What Is Gain?

The use of the term gain in audio is a derivative of the term voltage used in electronics. The difference in size between the input and output signal of an amplifier is called gain. It’s normally measured in decibels.

Another way to look at gain, is to compare it to opening a water tap. The more you open it, the greater the amount of water that comes out. In audio, this is the same type of thing, you put a signal on the input, and you get a larger magnitude at the output.

And while this might seem like the same thing as volume, as you will see, they are different. Let’s look at a few examples.

Gain on a Guitar Amp

Clipped sine wave signal

There are 2 main parts of an instrument amplifier:

  •  Preamp
  •  Power amplifier

The preamp stage is needed to amplify an input signal that is too low to be useful on its own. A guitar puts out a very small signal that cannot be used unless it’s increased in magnitude by a preamp.

The gain control on an amplifier lives in the preamp section of the circuit. This control dictates how much signal is allowed to proceed into circuits preceding it.

In the preamp of most guitar amps, you will find that there are many active gain stages. They are all connected together or cascaded in series. One gain stage boosts or amplifies the signal and passes it on to the next.

As the audio signal intensifies, it becomes too large for the following stages to handle. They begin to start clipping as a result. The gain of each stage simply begins to become too large. This produces the guitar amp distortion we know and love today. But not all clipping is good.

Gain On A Mixer

Audio Mixer Controls

The makeup gain or trim control regulates the amount of signal it receives from a device. Many devices like microphones and instruments can be used on a mixer. The audio signals from these devices can be drastically different.

The gain control is used to limit how much of the signal is allowed to proceed into the channel circuit.

The goal of the makeup gain control is to allow the strongest signal possible for optimal sound. All while preventing any distortion or clipping of the channel circuit. There is a dynamic range that you need to work within. A proper gain setting also keeps the noise floor artifacts in check.

Many people mistakenly refer to this control as a volume adjustment. Which is why this confusion exists in the first place. The volume of the channel is controlled elsewhere. While the gain keeps the sound quality in check by preventing distortion.

Too much or too little input signal will ruin sound quality in a hurry! It’s easy to assume that gain is volume because a larger signal will increase the loudness.

Signal Intensity

Another way to explain it is to consider setting the gain on a microphone preamp. The vocalist sings lightly into the mic. Normally, you would set the level just before the onset of clipping. This way you get a nice strong signal.

But if the vocalist sings louder, things change quickly! That channel is going to clip like crazy and distort the vocals for sure once they do. You can adjust your volume knob all you want, and that channel is still going to clip.

But once you turn your gain control down, the channel no longer clips. So what’s going on there?

The input signal got stronger when they began to sing louder, which then produced more gain. The extra gain then overpowered the rest of the channel circuit and clipped the audio signal. This had nothing to do with the volume setting. It didn’t increase a ton, but the channel sure got hit hard with a lot of audio signal gain!

What is Volume?

Volume, in audio, is the perception of loudness. It’s the intensity of sound waves produced by a speaker when powered by an amplifier or audio system.

The more powerful the amplifier, the louder the sound, which in turn means a higher volume. Most instrument amplifiers and sound systems have built-in power sections that drive speakers. Most people are quite familiar with the 100-watt Marshall guitar amplifiers. They are incredibly loud!

The volume on these amplifiers is produced by the power section circuit. But what is controlling these power sections making them louder or quieter? You guessed it, a volume or loudness control.

Audio Gain and Volume

Guitar Amplifier Volume

The master volume control on an amplifier is right after the preamp and before a power section. The volume control regulates how much of the signal is allowed to go into the power section.

With a higher signal going into the power section, more volume will be produced at the speakers. Do you remember when we looked at gain on an amplifier? The gain control set the signal intensity that would leave the preamp.

When the signal from the preamp goes up, the louder volume we get. If we use the analogy of a water valve, the signal flow through the loudness control is similar. When you open the valve and water starts to flow, you will get a nice stream at a decent pressure.

If the intensity from the water source goes up, the pressure through the valve will increase as well. No matter where it’s set, the flow will get stronger. If the intensity from the water source goes down, the pressure through the valve will decrease. The master volume control reacts the same way with the signal it’s provided from the preamp.

And so if the preamp signal becomes larger, the loudness would also increase. This is because the power section would also see a small boost in intensity. And so the assumption most people make is that the gain control is also a volume adjustment.

Mixer Volume

On a mixer with many channels, you will see faders or slider controls. These are the controls that deal with the volume from the mixer’s channels. They regulate the output for each one. As you slide the fader up, the output level from the channel gets stronger.

As you increase the faders, this begins to mix all the signals together. The combined audio eventually ends up at the master output. These master output faders are the mixer’s main volume controls. They then send the mixed output to another device that will amplify it. This is normally from studio monitors or PA speakers.

Audio Gain Vs Volume

Gain controls the amplitude of the audio signal as it travels through the device. Volume controls how loud the audio signal will be as it leaves the device.

When you break an amplifier into 2 parts, preamp and power, it makes it easier to understand. They essentially do the same thing, which is why it’s hard to grasp how gain isn’t a volume control.

The challenge for most people is the fact that they both do change the loudness when adjusted. So most people assume that somehow they interact with each other to control the volume. And this is true, they do interact with each other and both affect the loudness. So let’s look at how the signal flows through an amp. Also how it’s transferred between the 2 sections with diagrams.

We will look at different settings to see how the preamp responds. And also how the volume control reacts to different gain settings.

Making Adjustments

Gain Vs Volume Diagram

For the sake of this example, a guitar input signal of 1 volt is being used to keep things simple. An actual guitar signal is much lower, however. If you look at the input signal in the first diagram above, it’s a clean sine wave. Very similar to what the guitar signal might look like, depending on the frequency.

As it makes its way through the preamp, it comes to the Gain control set at 25%. This limits how much signal makes its way into the other stages. As the signal leaves the preamp, it’s still quite clean because of the lower gain setting. But we have a decent output of 16 volts thanks to the last 2 gain stages.

We then come to the volume control also set at 25% which then sends the signal into the power amp. At a much lower level than what was received from the preamp. The power amplifier then increases the signal it was sent by the volume control. An output level of 75 decibels is heard by the listener through the speakers.

We see that the preamp signal was clean. But because of the low gain and volume settings, there is little distortion.

Increasing Gain

Gain And Volume Diagram

In this diagram, we have turned the gain up to 75%. As you can see, the signal from the guitar is still 1 volt and is just as clean as it was in the first diagram.

With the gain control higher, we have a majority of the signal from stage 1 making its way to those downstream. This added audio gain hits the stages harder, driving them into distortion. Once the signal leaves the preamp, you can see that it’s distorted, the sine wave is clipped, and is now a 40-volt output!

The volume control in this diagram is still set at 25%. Like last time, it sends only a quarter of the preamp signal it has received. With a 10-volt signal, the power amp increases it and the listener experiences 82 decibels through the speaker. The sound from the speaker would be distorted thanks to the preamp.

So we see that an increase in audio gain on the preamp stage has created a volume boost of 7 decibels. This is not a very large increase and, while noticeable from the speaker, is negligible at best. Some of the bigger changes are that now the preamp output is heavily distorted!

This added signal has caused both distortion and altered sound from the added gain. But all from the preamp. Huge tone-shaping going on here! We also see that the preamp output has increased a lot from the first diagram. Yet we really only see a small volume change.

In this case, the volume control and power section will only increase the preamp signal. All without actually changing its sound.

Increasing Volume

Effects of volume diagram

In this diagram, we have left the preamp alone but cranked up the volume! We are now at a loudness level of 75% and things got loud! If you notice in this diagram, the gain setting is still at 75% and the preamp output and distortion are the same.

But now the volume control is letting a majority of the preamp signal work its way to the power amplifier. Our output is now at 120 decibels and wow what a change in intensity. 38 decibels difference from the volume control! Just as one would probably expect to have happened when turning it up.

The sound would still be distorted like the last diagram, but this time it’s just a lot louder. No change in tone would have happened with the increase in volume. Now, if we were to turn the gain control back down to 25%, the signal would become lower from the preamp.

It’s a negligible difference in volume, but a huge tone change instead! The sound would become cleaner because the preamp would no longer be distorting. It would still be very loud!

Remember to have hearing protection when using anything this loud for long periods!

What About Gain Staging?

Gain staging is another term that gets thrown around more so in the mixing environment. This term is used when the levels moving throughout devices like audio interfaces must be set to keep them balanced.

As devices and plug-ins are added to a signal path, they will begin to alter the level. As the signal gets processed by these added devices or plug-ins, the level will either be cut or boosted. This can create issues with the level and sound of the signal if they are not dealt with.

Gain staging is the term used when adjusting the levels at each device or plug-in that was added to the system. Each one is a stage, and the gain output from each one must be consistent in order to provide the right decibel level.

For example, if you add an EQ to the system, there is a good chance that any frequencies being cut or boosted will alter the level. The gain will need to be adjusted to obtain the correct signal level prior to the addition of the plug-in.

Conclusion

So the main thing to take away from this article is that the gain control does affect the volume to a degree. But it’s not a loudness control by any means! In fact, the gain control is by far one of the most important adjustments you will come across on audio gear.

Its main goal is to prevent distortion while providing the strongest signal possible. Or, its design is to create a rather large amount of distortion with huge tone shaping. What you would find on a guitar amp.

In either scenario, the gain knob will need to be set correctly to get the best performance from your equipment. So next time you tweak your gear, I hope that you look at the controls differently.

Once you understand the difference between gain and volume, not only will your sound improve, your controls should start to make a lot more sense too!

FAQs

Does gain increase volume?

Yes, any changes made to the gain control will impact the volume. This is because as the gain is turned up, the stages preceding it will be sent a stronger signal. This then increases the overall signal throughout. Providing slightly more volume at the output.

Does gain affect sound quality?

Yes, the gain will affect sound quality in a very large way! With a guitar amplifier, it has the ability to distort a signal and change it drastically. This is usually the desired sound.

On a mixer, it changes the sound quality and is normally poor if not set right. Any distortion is not desired in a preamp. Headroom is limited when the signals are large, and so a Gain control is used to find the best sound.

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Don East

My name is Don East, I'm the editor for Killer Rig. I've been playing guitar for over 20 years and have designed and manufactured products like guitar amps, effects pedals, and more. Over the years I have played in many bands and have a deep love for quality gear. I am an electrical engineer and have a passion for music gear, and now want to share what I know with the community!