Nearly every electric guitarist knows the benefits of tube amps, which are amplifiers that use vacuum tube technology, and why people love them. Many players swear by their vacuum tube amps, which are primarily responsible for the signature sound of a large number of well-known guitarists. But are they really louder than other amps?
Tube amps are really louder than other solid-state amps of the same wattage and power. There is some debate in musical and scientific communities about whether they actually are louder or just seem like they are, but this is an academic distinction.
We won’t be able to come to a definitive decision because this is ultimately a subjective opinion, but you’ll know more about tubes and the amps they power in just a few minutes. Let’s look at what a tube amp is, how it works, and why so many players prefer them over solid-state and digital amplifiers.
What Is a Tube Amp?
When an electric guitar gets played, the strings vibrate, but because the guitar body is not solid, there is little opportunity for the sound to resonate the way it does with an acoustic guitar. The electric guitar uses pickups and a tube amplifier to make it louder for the sound to be heard.
At its most basic level, a tube amp is a guitar or bass amplifier that employs vacuum tubes instead of transistors or other technology to amplify the signal it gets from an electric instrument.
The tube amp uses vacuum tubes to raise the strength of the electrical signal it gets from the guitar so that it is strong enough to drive the speakers so that we can hear the instrument.
So a guitar makes its sound like this:
- The string is plucked.
- The resulting vibrations stimulate the pickup.
- The pickup converts the vibrations into an electrical current.
- The current goes to the amplifier.
- The amplifier amplifies the signal.
- The signal reaches the speaker.
- The speaker vibrates, producing the guitar sound.
Why a tube amp is louder than a solid-state amp has to do with the physics of sound and sound waves, and we’ll get to that in a bit.
How Does a Vacuum Tube Work?
Without an extensive background in electricity, you might feel a little overwhelmed by some of what’s about to come. Stick with it. It’s not as complicated as it may seem at first.
A vacuum tube is a vacuum-sealed glass tube with an anode, a cathode, and a heater inside. When the cathode is heated, it throws off electrons, a process that is known as thermionic emission. When a positive charge is applied to the anode, the electrons are drawn to it.
This movement is an electric current and it is how the tube can take an electric signal from the guitar, strengthen it, and drive a speaker.
In 1904, John Ambrose Fleming invented the vacuum tube, and it powered the things that passed for electronics back then. Much larger than the transistors that would come along later, vacuum tubes are somewhat responsible for the size of those giant, room-filling computers we’ve all seen in black and white photos.
Transistors came along in 1947 and revolutionized electronics. The vacuum tube fell out of use almost entirely, though it does have some applications in our modern world. However, the main holdover– or at least the most widely known– is the guitar amplifier.
A Transistor Might Be Better Than a Tube
The way tubes and transistors work means they handle signals differently, and when it comes to overdrive and distortion, they yield wildly different results. Let’s take a look at some of the ways that a transistor might be better than a tube.
Distortion vs. Overdrive
Most electric guitarists use some form of distortion or overdrive to achieve the sound they want. Distortion is used to describe the growling sound a guitar makes.
An iconic example occurs in the Beatles’ “Revolution,” and another in the Kinks’ “You Really Got Me” (although that distortion came from an intentionally damaged speaker, not from tubes or transistors).
Overdrive is, in many ways, just a toned-down version of distortion. Distortion in guitar sounds is almost always generated by effects pedals, while overdrive can be achieved via the amp alone, but only if it’s a tube amp.
Why Tubes Create Overdrive
At its root, overdrive is the result of the amplifier’s limits. When a player drives his signal over the amp’s capacity to handle it, his sound is said to be that of overdrive. It is a warm sound, and good examples of this can be heard in nearly any Queen song.
The band’s guitarist, Brian May, almost exclusively uses a tube amp and very few effects pedals. He relies on the warm sound of a Vox tube amp and overdrives the signal to achieve his signature tone.
But back to the limitations. When the signal goes through the tube, it is like a liquid through a pipe. If you send more fluid through the pipe than that pipe can handle, it backs up, as there are physical limits to how much liquid can flow through it at one time.
When a signal is overdriven and becomes too much for the tube, the tube ends up clipping off the signal rather than allowing electrons to pool as did the liquid in the above example. This cuts off part of the waveform of the sound wave and creates the overdrive sound.
So by definition, overdrive can’t happen in a solid-state– or transistor– amp because a tube must be present. Achieving overdrive in a solid-state amp must come through the use of an effects pedal.
When a solid-state amp’s transistors have too much signal driven through them, they clip the signal, too, but they cut the waveform differently, producing a harder, grittier sound.
So Why Are Tube Amps So Loud?
To get the amp to overdrive, you have to turn it up. Loud. If you set your tube amp’s volume knob to 3, you’re not sending a huge signal to the tube, which means the tube can handle all of it and doesn’t clip anything. To get the overdrive, you have to turn the knob higher.
So when a guitarist using a tube amp gets asked to turn it down, he’s being asked to create a different sound, not just one at a lower volume. The asker may not know this, but that’s still what they’re asking.
Also, when a solid-state amp produces an overdriven, tube-style sound with the help of an effects pedal, that pedal is modulated to regulate the volume coming out of it. So a solid-state amp with an overdrive pedal can produce a tube-style overdrive sound at lower volumes than a tube amp can.
Overdrive is the main reason people use tube amps.
Tube amps are louder than solid-state amps because it is their nature. If a player isn’t after the overdrive sound from his tube amp, he will not need higher volume levels. But if he is (and most tube amp users are), he has to turn it up.
Tube amps are an essential part of modern music, even though their distinguishing feature is a piece of technology more than a century old. But the sound they produce is distinctive, and amplified instrumentalists around the world cherish it.
Getting that sound requires pushing the amplifier past its limits, and that means turning up the volume on them. Tube amps seem louder than solid-state or even digital ones because they are.