Should you leave a tube amp on all the time?


We are often told not to leave electronic equipment switched on, mainly to keep those electricity bills down. But what if turning it on and off all the time causes damage?.

One of these pieces of equipment where this question is often raised is tube amps. There are pros and cons to leaving your tube amp on for long stretches, and to turning it off right after use. We’re here to sift through all of the advice out there and give you the best answer to this riddle.

Long story short, unless you plan on using your amp a lot throughout the day, you should turn off your tube amp when you are done using it. Here’s why:

  • Tubes deteriorate with use, so leaving a tube amp on shortens tube life.
  • Many tubes produce a significant amount of heat. This heat can be drying and damaging to other parts of the amp.
  • Tube amps can be hazardous when left on and unattended. On top of heat production, a blown tube can quickly become a fire hazard.

You have probably heard or read conflicting information about whether or not you should leave a tube amp on all the time. Let’s unpack this information. Read on to see both sides of the argument and find out why the above answer is the best option.

Tube longevity

The argument over whether or not to leave a tube amp ever-on, or to turn it off, revolves around extending the life of the tubes. Whenever the amp is running, the tube life is slowly decreasing, just like a light bulb wears out over time. The most damage that a tube sustains at once, however, is when the amp is powered on.

Damage during turn-on

We’ve all had the experience of a light bulb suddenly burning out right when the light switch is flipped on. Yes, lights also burn out randomly while they are on, but turn-on is the most common time for the filament in a light bulb to burst. The same is true for the tube filament in an amp. But why is that?

Because, science! You know that energy produces heat, and that heat itself is a form of thermal energy. Think about steam, for example. Steam is made up of water molecules that have gained energy by being heated. This heat causes the water molecules to move faster and expand into a gaseous state. So, more heat equals greater expansion.

Now, think about a filament that has not been in use for a period of time. It is cold, the molecules of the metal are contracted, and the filament is brittle. When the amp is powered on, energy rushes into the filament, bringing the filament to a heated state of expansion very rapidly. If the filament is unable to adapt to the sudden change, it breaks.

Have you ever poured hot water into an icy cold glass? The sudden change in heat can cause the glass to fracture abruptly. Too much energy at once causes molecules to expand too quickly. A break is the only way for that energy to escape. This is similar to what happens when a filament blows in a tube when you turn on the amp. If you’re in the market for an amp, some have circuits that slow the inrush and can cut down on startup abuse.

Of course, in a properly functioning amplifier, you don’t blow a tube every time you switch the thing on. However, the argument has been made that leaving a tube amp on all the time exposes tube filaments to less damage over the life of the tubes. This might make sense, if not for one important factor: the tube filament continues to sustain damage while the amp is on.

Degradation while left on

While the risk of the tube filament blowing suddenly from a large jump in temperature is drastically reduced once the amp is already on, the filament will continuously break down because of the thermal energy running through it. This degradation process happens slowly, but it is constant, as long as electricity is flowing through the tube.

Remember the steam example that I mentioned above? When heated, atoms from the filament will slowly evaporate into the atmosphere inside of the vacuum-sealed tube. As these atoms evaporate, the filament becomes thinner and thinner, and it will eventually break at its weakest point.

As long as the electrical components of the amplifier and the power source are working properly, and the tube is not defective, filaments typically only blow when the amp is powered on because they are already weak from regular use. The sudden influx of heat is too much for the thinned filament to handle, and it breaks.

For this reason, it makes more sense to turn off the amp when you are done using it. If you plan on using your amp several times over a period of eight hours or less, leaving it on might make sense. Generally, turning the amp off when you are done using it for awhile will increase the life of your tubes in the long run.

The Rest of the Amp

It is no wonder amp owners are interested in finding the best way to extend the life of their tubes. They can cost anywhere from twenty-five to fifty dollars and up, with some amps requiring as many as five tubes. Further, the more a tube amp is used, the more often tubes need to be replaced for consistent quality and basic function of the amp itself.

While replacing tubes can be costly and annoying, keep in mind that replacing the entire amp is a much larger financial burden, with amps selling from hundreds to thousands of dollars. If you are still tempted to leave your amp on to prolong tube function, despite the explanation above, consider the health of your amp, overall.

The villain in this story is, once again, heat. Heat produced in the tube filaments can destroy other components of your amp when it is left on all the time. Elements, such as the electrolytic capacitors, can become dried out due to constant heat exposure, shortening the life of your amp as an entire unit. Proper use and maintenance is always the best way to extend the life of your equipment.

Safety Is King

Understandably, the longevity of your tubes and your amp are important to you. What about the longevity of your other possessions? It might sound drastic, but damage, or even loss, of other items in your home, and your home, itself, can happen when a tube amp is left on and unattended. Worst case scenario, a fire starts.

You’re already aware that tubes produce a lot of heat when the amp is on. There is always risk of damage wherever heat is involved, but the biggest issue with leaving a tube amp on all the time is if a tube blows. This can turn the amp into a dangerous hazard. It could even start on fire, which is a pretty big deal, especially if no one is around to call the fire department.

It’s a good idea to make a habit out of always turning your tube amp off after use, this way you’ll be less likely to accidentally leave it on overnight or when you’re out of the house. If you’re forgetful, or have gotten into the habit of leaving your tube amp on all the time, try using a timer to switch things off at a particular time, automatically. That way you’ll have one less thing to worry about.

Verdict

So, should you leave a tube amp on all the time? Hopefully, you can now answer this question with a confident, “No!”

Although the filaments inside the tubes take some abuse when you fire up an amp, most of the wear that filaments sustain happens while the amp is on. You’ll likely just end up wearing out your tubes faster by leaving them on all the time, because they will be continuously taking damage, even in standby mode.

Constant heat from the tube filaments also creates a dehydrated environment within the amp. This heat will wear out more than just your tube filaments. Other components of your amp can wear out faster if it is left on all the time. If you’d rather replace your tubes than your entire amp, turn it off when you’re done using it. It’s better for your tubes, anyway!

Turning your amp off is also the safest choice. As heat builds up over long periods of time, not only does your amp suffer, things can get dangerous. This is especially true if a tube blows and the amp catches on fire. If you’re not around, there is no reason to keep your amp running.

Safety is always one of the most important factors when making any decision. In this case, turning your amp off in between uses not only keeps you safe, it also extends the life of your tubes, and your amp as a whole, making this once mystifying riddle a no-brainer.

Rob Wreglesworth

Rob has come to terms with the fact he will probably never be a famous rock star....but that hasn't stopped him from writing and recording music in his home studio. Rob has over 15 years experience of recording music at home.

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