Whether you’re a complete beginner or want to upgrade your rig, one of the most important things you need to consider is the size of your amplifier. Different sizes are suitable for practicing, recording and performing live, and you don’t want to be stuck with an amp that’s too small, or overpay if you get an amp too large.
The Quick Answer
For practice amplifiers, a 5W to 30W amp is suitable and will weigh around 5-10kg and be approximately 40 x 30 x 25 cm in size. For gigging and live performances, a 50-100W solid state amp or a 30-50W tube amp is a good size. Combo amps setups are more compact and smaller than stack amp setups.
The size of amp can refer to either the wattage (power) or the dimensions. There’s a relationship between the two, with higher wattage amps often having a larger speaker so bigger dimensions, but it’s not always so straightforward. In this article, I’ll first discuss what wattage is best for different situations and then how to choose the best size.
Wattage and Volume
Wattage is a measurement of how powerful an amp is, and is one of the factors that affects how loud the amplifier will sound. When people talk about the size of an amp, a lot of the time they are referring to the wattage, but if you’re looking for more info on the dimensions, then I’ll go through that a bit further down in the article.
Guitar amps range in size from around 1W to 150W. Very small amps that have a wattage of under 5W are often called mini, or micro amps. Very large amps which are over 100W often come in “stacks”.
- Stack amps are made of two components: the head unit and the cabinet (speaker).
- Combo amps are an all-on-one system which contains both the head and the cabinet.
If you’re choosing a stack amp setup, make sure you are matching the wattage of the head unit and cabinet. Otherwise, you risk blowing the speaker if the cabinet is too small compared to the head.
If you’re not sure whether you need a combo or a stack setup, then take a look at my comparison between combo and stack amplifiers to easily identify which is the best option for you.
No matter what type you choose, you’ll need to consider what wattage is right for you.
An increase in wattage will cause an increase in volume.
But this is only one factor to consider, I’ll go through everything else you need to know after we’ve dealt with wattage. For simplicity, if a 10W amp and 100W amp of the exact same model and speaker (cabinet) size, then it would be louder. But how much louder?
The relationship between wattage and volume is not linear. So if you get a 10W amp and a 100W amp and keep all other variables the same, then the 100W amp will still not be 10 times louder than the 10W amp.
Here’s a quick table to show the relationship.
| Power (Watts) | Loudness Compared to a 1W amp |
| 10 | 2 times |
| 20 | 2.6 times |
| 50 | 3.2 times |
| 100 | 4 times |
As you can see, a 10W amp is only double the volume compared to a 1W amp, and a 100W amp is only twice as loud as the 10W amp.
It’s important to keep this perspective in mind when selecting the wattage. The difference between a 10W and a 100W amp is big, but the difference between a 40W and 50W amp is pretty minimal.
Tube vs Solid State Size
So I mentioned that wattage isn’t the only thing to consider. You also need to think about the type of amplifier you’re using. There are two main types of amp:
- Tube (valve): a tube amp uses valves (little glass cylinders) to amplify the signal produced by the guitar.
- Solid State: these use transistor circuits to amplify the signal.
Tube amps sound much louder compared to solid state amps. Generally, a 3 times increase in wattage is needed on a solid state amp to sound the same volume as a tube amp. For example, a 10W tube amp, will likely sound a similar volume as a 30W solid state amp.
Notice how I’ve said “sounds louder”. That’s because it isn’t actually any louder. If all variables were kept the same, tube and solid state amps of the same power rating (wattage) would be the same volume. However, tube amps are perceived as louder than solid state amps.
Tube amps compress the sound differently to solid state amps. Tube amps distort the signal at high volumes which is often perceived as an increase in volume. However, solid state amps produce distortion at high volumes which is perceived as just that, distortion, instead of a volume increase.
Make sure you check my in-depth guide comparing solid state and tube amplifiers so you can decide which is the best option for you.
So what wattage do I need?
This does depend on the cabinet as well (next section) but here are some numbers to give you a rough guide.
| 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 |
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Cabinet Size and Type
The cabinet also dictates how loud the amp is. Some solid state amps have multiple cabinet options to choose from, as well as power ratings, however this is something you have more control over if you’re choosing a stack amp set-up.
First let’s talk about open and closed back cabinets.
- Closed back cabinets focus the sound more, since it only comes out of the front of the speaker.
- Open back cabinets allow the sound to exit from the back and front of the speaker which helps to fill the room and sounds louder in bigger venues.
Now moving onto the cabinet size. The three most popular cabinet sizes are: 1×8″ 1×10″, 1×12″, 2×12″ and 4×12″. A 2×12″ cabinet will sound louder than a 1×12″ cabinet, even when using the same amp, because the 2×12″ creates more air flow.
Larger cabinets generally change the frequencies given out. Larger cabinets have more bass than smaller cabinets, again contributing to them sounding louder.
Check out this comparison between 8″, 10″ and 12″ speakers to learn more.
Dimensions
As well as considering the size of the amp in terms of the power rating, making sure you thing about how much space it’ll take up, and how heavy it is. If you’re going to be gigging, then having something super heavy might be a bit of a nightmare. Also, a big amp will take up a lot of space if you’re getting the amp for your house.
To help put things in perspective, I’ll listed some popular combo amps, head units and cabinets, as well as their weight and dimensions so you can see roughly what size you need to look at.
If you’re looking for a very light and compact setup, then a solid state combo amp is a good choice. Tube amps of the same wattage will usually weigh around 2-3 times more than solid state amps. Stack amp setups are good for customisation but heavier and larger overall than combo amps.
Solid State Combo Amps
| Amplifier | Dimensions (cm) | Weight (kg) | Wattage |
| Marshall MG10G | 34.9 x 18.4 x 30.5 | 4.8 | 10W |
| Fender Champion 20 | 40.6 x 30.5 x 40.6 | 5.4 | 20W |
| Marshall MG30GFX | 48.0 x 42.0 x 22.0 | 10.8 | 30W |
| Peavey Vypyr X2 | 45.0 x 49.5 x 25.4 | 12.7 | 40W |
| Boss Katana 50 | 47.0 x 23.8 x 39.8 | 11.6 | 50W |
| Orange Crush Pro CR60C | 55.0 x 45.0 x 29.0 | 20.25 | 60W |
| Boss Nextone Artist | 57.2 x 47.5 x 24.8 | 16.2 | 80W |
| Boss Katana 100 2×12 | 53.0 x 48.4 x 24.8 | 14.8 | 100W |
Valve Combo Amps
| Amplifier | Dimensions (cm) | Weight (kg) | Wattage |
| Marshall DSL5CR | 45.5 x 42.5 x 24.5 | 12.7 | 5W |
| Fender Bassbreaker 007 | 51.8 x 49.8 x 29.8 | 11.0 | 7W |
| Vox AC10C1 | 60.3 x 47.3 x 30.7 | 11.8 | 10W |
| Orange Rocker15 | 47.0 x 41.0 x 26.0 | 13.6 | 15W |
| Marshall DSL20CR | 50.0 x 42.0 x 25.0 | 16.3 | 20W |
| Orange TremLord-30 | 57.5 x 46.5 x 29.0 | 29.09 | 30W |
| Blackstar HT Venue 40 | 58.8 x 48.0 x 26.0 | 24.0 | 40W |
| Marshall JMV215 | 60.5 x 51.0 x 26.5 | 26.5 | 50W |
| Fender ’68 Custom Twin Reverb | 50.5 x 66.4 x 21.9 | 29.0 | 85W |
Head Units
| Amplifier | Dimensions (cm) | Weight (kg) | Wattage | Type |
| Blackstar HT-5RH | 44.3 x 29.9 x 22.8 | 12.3 | 5W | Tube |
| Fender Bassbreaker 15W | 49.5 x 24.8 x 22.4 | 11.56 | 15W | Tube |
| Blackstar HT20RH | 46.7 x 24.4 x 22.1 | 9.57 | 20W | Tube |
| Orange Dual Terror | 36.0 x 19.0 x 18.0 | 9.75 | 30W | Tube |
| Orange Rockerverb 50 | 55.0 x 27.0 x 28.0 | 20.75 | 50W | Tube |
| Marshall JMV210H | 74.0 x 31.0 x 21.5 | 22.0 | 100W | Tube |
| Boss Katana | 47.0 x 22.8 x 21.5 | 8.8 | 100W | Solid State |
| Vox MVX150H | 52.0 x 21.9 x 19.4 | 7.1 | 150W | Solid State |
Cabinets
| Amplifier | Dimensions (cm) | Weight (kg) | Speakers | Max Power (W) |
| Orange PPC108 | 26 x 26 x 16.5 | 4.05 | 1×8” | 20W |
| Kustom Defender | 43.2 x 45.1 x 25.4 | 9.30 | 1×12” | 30W |
| Laney Cub 212 | 70.0 x 42.0 23.0 | 14.5 | 2X12” | 50W |
| Fender Bassbreaker | 49.5 x 44.5 x 23 | 9.52 | 1×12” | 70W |
| Marshall CODE 212 | 70.0 x 52.5 x 30 | 20.2 | 2×12” | 100W |
| Orange PPC21OB 2×12 | 70 x 54.5 x 30 | 31.65 | 2×12” | 120W |
| Marshall JMVC212 2X12 | 69 x 49 x 26.5 | 24.0 | 2×12” | 150W |
| Marshall CODE 412 | 69.5 x 67.5 x 39.0 | 24.0 | 4×12” | 200W |
| Marshall 1960v | 75.5 x 77 x 36.5 | 40.6 | 4×12” | 280W |
What Size Amp Do You Need?
Before I wrap things up, I wanted to talk about the size of amp you might need depending on your requirements.
Home Practice
To use an amp at home for practicing, then a 10W to 30W solid state amp will be the best size, or a 5W to 10W tube amp. The dimensions of combo amps in this category is around 40 x 30 x 25 cm, and will weigh around 5-10 kg.
Gigging and Live Performances
For gigging and live performances, a 50-100W solid state amp, or a 30-50W tube amp will be a good size. This will likely weigh around 15-25 kg and the dimensions will be around 50 x 40 x 25 cm.
Recording
For recording, a solid state amp that is around 50W or a tube amp that is around 20-30W is a good size. The amp should not have a very high power rating or the volume required may be too high to get a good tone. The weight will be approximately 10-15kg and the dimensions around 40 x 30 x 25 cm.
In the market for a new amplifier? Check out my complete amplifier buyer’s guide to help narrow down your selection and find the perfect amp for you.
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