How Loud Does an Amp Need to Be? A Guide to Wattage


The tone of an amplifier is super important, but so is the volume. If you want to play live, then you’ll need enough volume so that you can fill the venue with sound. So how loud does an amp actually need to be?

In this article, I’ll go through the different types of amps and how the wattage affects how loud they are. Then I’ll discuss how many watts your amp actually needs, and the other factors you’ll need to consider. So let’s get started!

The Quick Answer

For home use your amp should be around 20W. For most gigs and live performances in venues that hold around 100 people, you should have either a 20W tube amp, or a 40W solid state amp if you’re playing without a band. If you’re playing with a drummer, you’ll likely need a 100W solid state amp, or a 50W valve amp.

For larger venues holding hundreds or thousands of people, you’ll normally need a 100W tune amp, or a 200W solid state amp with a microphone in front. 

How Loud Does an Amp Need to Be?

Purpose Solid State Valve/ Tube
Practice amplifier 20W 10W
Gigs with no drummer in venues holding <100 people 40W 20W
Small gigs with a drummer 100W 50W
Gigs with 100-1000 people 200W 100W
Gigs with >1000 people 200W and microphone 100W and microphone

The wattage is only part of the story though, there are also several other factors you need to consider when choosing an amp for live performances. 

What Affects the Volume of an Amp

There are several factors that affect how loud an amp is. These include the power (wattage), the cabinet size and type, and the amp type ie. tube (valve or solid state). 

Wattage

The reason why wattage is so talked about when it comes to defining volume, is because it’s one of the easiest ways to compare different amps together. To understand how wattage works, we need to go through the science really briefly.

A watt is a unit of power. The more watts an amp has, the more powerful it is. There is a relationship between an increase in power (watts) and an increase in volume. So does that mean a 100W amp will automatically be louder than a 10W amp? Not exactly.

It’s also important to remember that the relationship between the number of watts, and the loudness of an amp, isn’t linear. For example, a 100W amp isn’t 10x louder than a 10W amp. In fact, the difference is actually quite small. 

The difference in decibels (dB) between a 50W and 100W amp, is usually around 3dB. To put this into perspective, the sound of your own breathing is around 10dB. It actually takes an amp to have 10x more watts, to be perceived as twice as loud to most humans. 

Take a look at these two charts. 

amp volume
Change in Power (Watts) Volume Increase (dB) Increase in Loudness
2 3 1.23x
4 6 1.52x
10 10 2x
100 20 4x
1,000 40 16x
10,000 80 256x

Hopefully this helps things make a bit more sense. So if you were to increase the power in watts by 100, this would result in a volume increase of 20dB, which would mean it would be 4x louder. So a 10W amp for example, would be twice as loud as a 1W amp. 

You need a really big increase in the number of watts to get a very noticeable increase in volume. So don’t choose a rubbish 50W amp over a better quality 40W amp, just because you think it’ll sound louder. Because the truth is, it won’t make a huge amount of difference. 

The Speaker (Cabinet)

There are some other factors that you need to consider, as well as the power. The cabinet (speaker) dimensions are also important. For example, as 100W amp played through a 1×12 cabinet, will sound quieter than when it is played through a 2×12 cabinet. 

This is because the 2×12 cabinet will generate twice as much air movement, hence causing it to sound louder. 

Also, there are open back and closed back cabinets. Open back allows sound to exit the speaker from both the front and back of the cabinet. This tends to fill the room a bit more, which is great if you’re playing in a larger venue. Closed back cabinets tend to sound more focused, since the sound is only coming out of the front of the speaker. 

The type of amplifier is also important… 

Tube (Valve) vs Solid State

It’s also important to be clear about the difference between tube and solid state amps, when it comes to volume. 

A tube amp will usually sound louder than a solid state amp when they both have the same number of watts. This is due to the way that tube amps compress the sound, which gives the impression that they’re louder. 

Tube amps distort the sound when you crank up the volume, and it’s this distortion which tricks your ears into thinking it’s louder. 

The reason why this doesn’t happen with solid state amps, is because the distortion you hear when you crank the volume up, is a lot more obvious. 

When you increase the volume of a solid state amp, it’ll sound a lot more distorted. But when you crank the volume of a tube amp, it’ll sound louder, instead of more distorted. 

How to Estimate Loudeness

Okay so knowing how wattage, cabinet size, and amplifier type affect volume is all well and good, but how do you actually know how loud an amp will sound?

Well, this is pretty tough to actually answer. It really depends on the variables (cab size, wattage and amp type). However, here are a few examples that’ll help.

  • A 100W amp, will usually sound around 2 times louder than a 10W amp, if they have the same speaker size and they’re both either tube or solid state. 
  • A tube amp will normally sound twice as loud as a solid state amp, if they have the same wattage and speaker size. 
  • An open back 2×12 cabinet will fill the room with sound better than a closed back 1×12 cabinet. 

How Loud Should an Amplifier Be?

Now we know what affects loudness, and where power (watts) comes into play, let’s talk about the different uses of amplifiers, and how loud they need to be for each purpose. 

Practise Amplifiers

The majority of practice amps are solid state, and have around 20 watts. This is definitely enough to get good quality audio, at pretty high volumes. If you’re looking at tube (valve) amps, then around 10 watts is usually enough.

You don’t want to go too high in terms of power, because you may not be able to get enough grit and distortion if you always have to have the volume so low to avoid annoying your neighbours!

Clubs and Bars

The number of watts you need to gigging in a club or bar that holds around 50-100 people is usually around 20 watts for a tube amp, and 40 watts for a solid state amp. If you’re playing without a ban, that is.

If you are playing in a band with a drummer, you’ll need a boost in volume so your sound doesn’t get completely drowned out. You’ll need a solid state amp that has around 100 watts, or a valve amp that has around 50 watts. 

This will usually give you enough volume that you can be heard over the drummer, without having to push your amp’s volume too hard so that the distortion becomes overbearing. 

Larger Venues

If you’re playing in larger venues, then you’ll normally have your amp’s volume boosted by a microphone. This is the easiest way to get that boost in volume without having a ginormous speaker and amp.

For large venues, holding few hundred to a few thousand people you’ll normally need either a 100W tube amp, or a 200W solid state amp. Of course, you can then adjust the microphone volume depending on the specific venue size. 

Recording

Typically, if you’re using your amp so recording purposes, you’ll normally want a solid state amp that has around 20-40W or a valve/tube amp with around 10-20W. 

Volume isn’t as important in the recording studio. But you do need to get the balance between having an amp that’s actually loud enough without you having to push it too much or little, so that the distortion effect is either too obvious or too weak. 

how loud does amp need to be

 

So there you go! That’s how loud an amplifier should be for gigging and practising! I hope you’ve found this article helpful, thanks for reading. Here are some other posts you might find useful:

Heather

Hey, I'm Heather. I started playing an electric guitar when I was given a Squier Strat for my birthday around 15 years ago. I now own an acoustic guitar and several electric guitars including my personal favourite, a PRS SE Custom 24.

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