Everything You Never Knew You Wanted to Know About Tube Amps

I was at my local music store over the weekend, checking out some new acoustic guitars for an upcoming camping trip when I overheard a discussion about amplifiers.

That discussion got me thinking about common questions and misconceptions people have about tube amplifiers.

Here is a list of FAQs and their answers.

Q. Are Tube Amps Worth it?    

There’s simply nothing like pure tube tone in a guitar amp. This is especially true in a large room with good acoustics. That doesn’t mean there aren’t some downsides though.

In fact, I’ve already mentioned one – you need a fairly large room.

Tube amps sound a lot louder than solid state amps, and are typically not well suited to bedroom practice or coffee club sized venues.

(Keep reading to see some exceptions to this.)

Another disadvantage to tube amps is that tubes eventually need to be replaced. Even with a premium set of vacuum tubes, they eventually grow old and die. Tube amps require more maintenance than solid state amps. Tubes need to be replaced, but they also need to be treated properly in order to get the expected life and performance from them.

Tube amps also tend to cost more and weigh more than their solid state counterparts.

Whether tube amps are worth the cost and care is ultimately up to the player though.

Q. What is the Advantage of a Tube Amp?  

Enough about the disadvantages of tube amps. What are their advantages? 

In a word: Tone

We would not have rock and roll (and almost everything that came from it) if it wasn’t for the way an electric guitar’s tone breaks up when run through a vacuum tube and pushed outside the intended volume.

Whether it’s a searing blues lead, glassy treble boosted tone or fat, creamy overdriven tone you’re after – it came from a tube amp in the beginning.

Read on to learn why people say tube amps sound better.

Q. Are Tube Amps Better Than Solid State? 

First of all, tube amps aren’t “better” than solid state amplifiers. They’re just different.

To some, that difference makes them better. To others, that difference makes them expensive and impractical.

Tube amps sound better because of harmonic distortion. Harmonic distortion, in a tube amp, is known as second-order harmonic distortion, which means that any given note also produces a distortion an octave above that note.

Harmonic distortion is good distortion. It’s musical distortion. 

It’s not necessarily the kind you find in metal or even hard rock, but it’s what gives your tone a certain “fatness” and fullness. That’s what you get inherently with tube amplifiers. It happens naturally, whereas you have to simulate this distortion in a solid state or digital amp.

On the other hand, it may have to do with the fragility of the harmonics in a vacuum vs a crystal lattice where electrons are concerned.

Huh?

Wait, what did I just say?

I’m not going to pretend to understand that myself. It’s my attempt at paraphrasing Howard Alexander Dumble, living legend and bona fide amp wizard.

The world of guitar amplification is full of amp wizards who got their start with various big name bands or guitar legends, and go on to form their own companies and mass produce their goodies. Bogner, Rivera, and Soldano are a few names in this field. Jose Arrendondo is another. He gained notoriety in the 80’s for his work on Eddie Van Halen’s Marshalls.

That’s not Dumble.

Dumble is legendary like Bigfoot as much as he is like Arrendondo and company. Maybe mythical is a better word. He’s a recluse by nature, and fiercely protective of his magic, even going so far as to blanket the electronics of his amps with a black epoxy like substance to keep prying eyes from reverse engineering his components. That’s hardcore.

He must be doing something right because the list of guitarists who prefer(red) Dumble amps is impressive. Stevie Ray Vaughn, Larry Carlton, David Lindley, Steve Lukather, Eric Johnson, Lowell George, John Mayer and Kirk Hammett are just a few proud Dumble owners.

His amps can go for $10,000 – 20,000 and if you want him to make a custom amp just for you, it’ll cost you a 10k deposit for the chance to play for him, because only if he likes what he hears will he work for you. Even then, you’ll get it when it’s done. He works on his own schedule, not yours.

Dumble On Why Tube Amps Are Better Than Solid State Amps.

Here’s a video of H. Alexander Dumble describing as only he can why tube amps are better.

Q. Are Tube Amps Reliable?   

The short answer: yes.

The detailed answer: When properly maintained and cared for, modern day tube amps a quite reliable. They are not as reliable as solid state, simply because integrated circuits don’t break down over time like vacuum tubes do. 

Q. Why do Tube Amps Sound Better? 

This has to do with harmonics and breakup. 

Here’s a simple image that can help us visualize the difference between digital (solid state) audio signal and tube (or analogue) audio signal:

digital vs analog audio signal

Image courtesy of https://www.klipsch.com/blog/digital-vs-analog-audio

The digital signal is created by staging many discrete units of sound (I am grossly over simplifying, but this is just for illustration) while the analog signal is a more natural curve.

You can also think of this as being the audio version of an image. If you’re old enough (like me) to remember when pictures were taken with 35mm film and a manual camera, then this will be an effective analogy. 

You can think of the sound produced by tube amps as being akin to the image produced with a 35mm film camera. Conversely, the sound produced by a solid state amp is like a picture taken with a digital camera, or smartphone. 

The film camera takes a more natural image just as the tube amp makes a more natural sound. This sound is even better at loud volumes.

And this is key.

Much the way a digital image looks noticeably worse when taken with old equipment at low pixel resolution, so too old solid state amps sounded terrible as you cranked the amp louder.

And, just like modern digital photography, modern digital guitar amps have come a long way and are now at a point where most people can’t hear a noticeable difference – especially at bedroom levels.

However, for the true audiophile, there is no substitution for pure tube tone.

Q. Are Tube Amps Louder Than Solid State Amps?  

The short answer: No.

The more in-depth answer has to do with the harmonics of tubes and clipping of the audio signal.

audio signal clipping

In the graphic above, the blue line illustrates a sound wave that represents the signal from your guitar. As the volume is raised (ex: gain is raised or an overdrive pedal is used) the signal is clipped and starts to distort. In a solid state amp, this clipping is accompanied with a rapid drop off in perceived volume compared to a tube amp. When tubes are overdriven, the harmonics extend past the red line a bit. This makes a tube amp sound louder to human ears.

Read more here.

Q. What is a Class “A” Tube Amp?

A class A tube amp is one which is wired to be always ready. Some amplifiers have a standby mode, these are class AB amps. They need to “warm up” before the tubes are ready to fully engage. 

Class A amps are ready to go when you are!

Here’s more…

Advantages:

  • The tube always warmed up and ready to amplify the signal.
  • Tube does not have to “wake up” from a “ready” state.
  • Class “A” amps have greater output than Class “AB” amps. If two EL84 output tubes in a Class A design may produce only 10 watts of output power, then the same two tubes in a Class AB design might produce 50 watts.
  • Smooth compression.
  • Less headroom. (NOTE: This is a disadvantage to some musicians who are looking for good, clean tone at higher volumes).
  • More responsive to the touch – i.e.: feels good to play.
  • Class A amps with EL84 tubes in push-pull design emphasize high order harmonics. This emphasis makes the amp “sing”.

Disadvantages:

  • Keeping the tubes warmed ready requires more current at all times. This constant current leads to shorter tube life.
  • Lower power rating than a Class “AB” amp with the same tube configuration.

Read more here:

Q: Is A Valve Amp The Same As A Tube Amp?

Yes. What Americans call Tubes (or vacuum tubes), Brits call Valves. It’s that simple.

Q. What Should I Look For When Choosing A Tube Combo Amp

Combo tube amps are so named because they have both the amplifier and speaker combined into a single unit. Each component of the amplifier as well as the speaker affect the tonal quality of an amp.

Here’s how each component affects an amp’s tone.

Tubes And Amp Tone

Amps are often times characterized as sounding either “British” or “American.” This tonal quality is brought about by the tubes used in the power and pre-amp sections of the amplifier’s circuitry. 6V6 and 6L6 tubes impart an American sound (think Fender), while EL84 tubes create that Vox “chime.” EL84 tubes give Marshall amps their glorious crunch. These are general rules of thumb, but it’s a good way to view the effect of certain tube types.

Want to get that Stevie Ray Vaughn tone? Go for an amp with 6L6 tubes.

Want that AC/DC Marshall tone? Go for EL34 tubes.

If you’re more of a Beatles or Queen tone hound, better shoot for a Vox sound with some EL84s

Wattage, Headroom And Volume (Oh My!)

In a simplified sense, you can think of a guitar signal as a sound wave. When a guitar signal is amplified, the sound wave is enlarged. If it’s enlarged (amplified) so much that it fills the box, then the signal is clipped (distorted).

The amount of space in the box is called “headroom.”

The larger the wattage of a guitar amp, the more headroom it has. The more headroom an amp has, then the louder you can crank it before the sound distorts.

This is why low watt tube amps are great for home use. You can get great crunch and distortion at low volume.

Speaker Size

As a rule of thumb, the larger the speaker size, the warmer the sound. Larger speakers can reproduce more low end frequencies and tend to have a fuller sound. There is a sweet spot though. 8-12 inches is a good size for full sound. Anything larger tends to be less focused, and smaller speakers tend to trend toward treble heavy, even shrill and tinny.

Open Vs. Closed Back Cabinets

The cabinets is where the speaker is located. This may be fulling enclosed, or partially open. Closed back cabinet amps have a tighter, more focused sound. Open cabinets allow some of the sound to escape into the room. This can result in a more open, ambient sound.

Some are decidedly vintage style, while others are classic or modern style. Whatever your personal taste, you should be able to find a low watt tube amp to your liking on this list of the best small tube amps available today.

Q. What is the best tube guitar amp? 

The best tube amp ever? Hands down, no argument? 

That depends.

(Don’t you just love when people answer your question like that?)

But seriously, it does depend. 

There is no single, magical “perfect at everything” amplifier. The best I can do is give you some “best in…” categories:

Tube Combo Amps for Beginners (and Budget-Minded Buyers)

These are simple, no frills tube amps. Rock solid and versatile, but chosen for budget buyers and those who don’t want the technology to get in the way of playing..

Small, Low-Watt Tube Combo Amps (for Home Practice)

These are great little amps that are perfect for the bedroom, home practice and small gigs. They offer the best tube tone has to offer, without the ear-splitting and back breaking size of more traditional tube amplifiers.

Tube Amps for Clean, Crisp American Tone

This is a great list of tube amps that will give you clear, crisp, sparkly American style tone that Fender amps are famous for. Great for Blues, Classic Rock and clean lead tone. 

Tube Amps for British Crunch

Looking for vintage AC/DC style tone, or Classic Rock with more edge and crunch? You probably want to check out these British tone amps. Also great for metal.

Tube Amps for Blues

If you’re looking for the best blues amp for good sustain and creamy overdrive, and you’ve got a bit more of a budget – this list is for you!

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