Understanding tube amps does not have to be difficult with our easy to follow overview guide. Tube amps are a type of amplifier that is used to make the guitar sound louder and better. Tube amps work by sending electricity through a vacuum tube, which creates a sound wave – making them very different from solid state amplifiers.
Before you purchase a tube amp for your guitar there a few things you should know.
The Benefits of A Tube Amp
Tube amps have a few key benefits that set them apart from other types of amplifiers. For starters, they provide a more natural and warmer tone than solid state amps. This is because the sound wave is created by electricity passing through vacuum tubes, rather than through transistors.
Tube amps also have a unique responsiveness to guitar players’ picking habits. Because the sound wave is created by tubes, the amp responds to how hard a string is plucked as well as where on the string it’s plucked from. This allows for a greater range of tonal variability and expression. Below is a great video from Fender for their 57 Tweed (tweeds are one of my go to amps) reissues that shows how great tube amps can sound.
Tube amps also tend to be a bit louder than their solid state counterparts, making them perfect for gigging musicians.
Additionally, they are often more durable and reliable than other types of amps. Hand wired tube amps will last a lifetime with some basic upkeep and can easily be worked on by a skilled technician. Amps using PCB boards are often disposed of if something goes wrong with the circuit board.
Disadvantages of Tube Amps
Tube amps are by far some of the best amps a guitarist can get their hands on if you want a high quality sound from your guitar. However, tube amps come with a few downsides too.
Because of their wattage rating, they can be a bit too powerful for home use and can easily damage your loudspeakers. If you find yourself in this category, you may want to check out our Best Small Low Watt Tube Amps to find something to meet your needs. The VHT below is a great example of a low-watt tube amp that sounds amazing.
Additionally, they can be quite expensive when compared to other types of amplifiers.
But, if you’re looking for an amp that will give your guitar the perfect tone, then you need to know what tube amps are all about!
Tube Amp Power Section
Power tubes work by using electricity from a power supply and creating sound waves. They first take information given to them by the preamp tubes and amplify it and send it to the speaker. Their role is to make the signal louder. They also can distort the sound, which is what gives tube amps their characteristic tone.
There are different types of power tubes that you can use in your tube amp. The most commonly used tube is the 6L6, which has often been described as providing cleaner, less distorted sound. Other types of tubes include EL34s which offer smooth distortion with chimey highs, the 6550s offer powerful cleans along side a low end frequency spectrum and KT88s can provide optimal high gain distortion tones. The Fender Blackface amps are a great example of a 6L6 power tube sound.
Preamp Tubes for Guitar
Preamp tubes are one of the most crucial parts in a tube amp because they shape the tone of the sound that is sent to the power tubes. Without preamp tubes, there would be no way for a guitarist to get their desired tone out of the amp. The preamp tubes do this by acting like one part of an electric signal chain. They take guitar volume and vary it so that it can be sent to the power tubes, which act as the last part of this chain. This is why preamp tubes are so important in tube guitar amps.
Different preamp types and brands will all create different tones. Preamp tubes are a less expensive way for experimenting (aka tube rolling) to see how different tubes impact the tone of your guitar. There are a variety of new old stock (NOS) tubes available in addition to current production models for you to try out. I usually checkout Tube Depot for NOS tubes.
We will try to do a full write up on what a guitarist should look for for in a preamp tube. In the meantime, make sure to checkout our How to Change Guitar Strings and our History of the Reverb Effects Pedal for more great tips and tricks.
Guitar Tube Amp Class Types
To further understanding tube amps, we will take a look at the different classes of amps. There are three classes of tube amps: Class A, Class AB, and Class B. These refer to power amplifier categories and provide a general picture of the amp’s characteristics and performance
Class A Tube Amp
At all times, Class A amps conduct over the entire range of the input cycle, and they are prepared to amplify instantly at all times since the tube does not have to “wake up.” At the same wattage, a Class A amplifier will sound louder than a Class AB amp. The current is always at its maximum, resulting in smoother compression.
The main drawback for Class A guitar amplifiers to consider: constant maximum current means that the tubes are continuously being used, which reduces lifespan and lowers power rating. Tubes are not cheap, trust me.
The Supro Delta King below is an example of a Class A amp.
Class B Tube Amp
Conversely, Class B is less expensive than Class A. When the output devices are not in use, no current flows through Class B amps, so they must be turned on from a zero-current condition. This extends the life of your tubes and a Class B amplifier can use a less robust power transformer.
The drawback is Slower slew rates in Class B amps may lead to a mushy sound.
Class AB Tube Amp
Class AB amps have a similar sound to Class A amps but will often be less expensive mainly due to not being as demanding on the power transformer. A Class AB typically will have more headroom along with longer tube life than their class A counterpart.
The main drawback to Class AB compared to Class A is you lose some of the responsiveness and they will not produce the same volume as a Class A with similar watts.
The Vox AC 30 is a cross A / Class AB hybrid. When running clean it is Class A but switches to Class AB when the amp is pushed the least bit.
What to Choose and Budget
Ughh, just like all things on our musical journey, budget is going to play a role. We all love premium amps but there are a lot of times that a high priced amp does not work for our particular playing style. My best advice is to identify your budget ahead of time and stick to it finding the best amp that suits your particular needs
Wrap Up for Understanding Tube Amps
While all of this may seem like a lot to take in, it’s important to remember that tube amps are still very popular for a reason. They can create some of the most amazing tones that you’ll ever hear, and they’re perfect for those who want to get the most out of their guitar. If you’re ready to take your tone to the next level, then a tube amp is definitely the way to go!