Many guitarists prefer tube amps over solid-state amps because they have a well-rounded sound and much more power. However, while tube amps sound great, they are more fragile and require more maintenance than solid-state amps. The vacuum tubes in a tube amp are made of glass, and although they are built sturdy, they will wear out, crack, and break over time. Of course, you can always take your tube amp to a guitar technician to have it repaired, but if you are anything like me, you like to do things yourself.
In this article, I’ll walk you through how to replace a broken tube in your guitar amp and answer some frequently asked questions on tube amp maintenance.
Step-by-step guide: how to replace a tube in your guitar amp
Replacing the tubes in your amp is not as difficult as it may seem, but there are a few steps and precautions to take before you start. Check out my tube amp troubleshooting guide if you have other issues with your amp.
Tools and supplies list
- New tubes
It is vital to ensure that you power off your amp and unplug it when messing around with any of the internal hardware. Tube amp capacitors have some serious electrical power that can be very dangerous even when UNPLUGGED, so take extreme caution when replacing any parts, and never take the amp apart. It is always safer to leave the complex repairs for the professionals.
The tubes also get very hot whenever the amp is on, so be sure to turn the amp off, unplug it, and leave it alone for at least 30 minutes before replacing the tubes.
Step one: remove the back panel
Use a screwdriver to remove the screws securing the back panel to the main box of the tube amp. Place the screws somewhere safe and remove the rear panel. Be very careful not to touch any of the wiring of the amp while the amp is on. With the amp open, you will see the larger and exposed power tubes and the smaller preamp tubes that are usually covered by a metal case.
Ensure the amp is turned off and cool before you touch any of the tubes with your hands or remove the casing of the preamp tubes.
Step two: locate the faulty tubes
The only time your amp should be turned on when the back is open is when identifying the broken tubes. Be very cautious and never touch the tubes with your hands as they may burn you severely.
Inspect the tubes to see if there are any visible cracks. If you cannot see any visible damage, turn the amp on and use a small wooden spoon or chopstick to tap all of the power tubes lightly, they will make a muffled tapping noise if they are in good condition. A broken tube will either make no sound at all or a high-pitched clinking sound.
Step three: switch the power off
Once you have located the faulty tube, shut the power off in your amp and unplug it. It is essential to wait at least 30 minutes before physically touching the amp because tubes can get as hot as 300 degrees!
Step four: remove faulty tubes
Once you have let the amp cool, remove the broken tubes.
To remove power tubes, push slightly on the metal grips holding the tube in place and carefully rock the tube until it is free from the amp.
To remove preamp tubes, you’ll first need to remove the metal casing. Push down on the case and turn it counterclockwise. The metal casing should then pop off. Then you can simply pull the tube out of the amp.
Step five: install the new tubes
Once you have removed the broken tubes, you can place the new tubes. Line up the power tube plug with the holes inside the amp, push up on the metal grip, and slightly move the tube from side to side until it is secured. For the preamp tube, line up the tube and wiggle it back and forth until it is firmly placed.
Step six: replace the back panel
After the faulty tubes have been successfully replaced, line up the back panel with the tube amp box and screw it back in.
Now your tube amp should be good to go, and you can finally plug your electric guitar back into the amp and start jamming!
How to tell your tube amps need to be replaced
There are a few warning signs that your tube has burnt out, cracked, or is microphonic.
- The tube amp makes no sound when your guitar is plugged in and powered on
- The tone is off (high-end or low-end deficiency)
- The amp is much quieter than normal
- Unusual feedback or high-pitched squealing
If any of these occur in your tube amp, check the tubes and replace any faulty ones.
Difference between preamp and power tubes
There are two types of tubes: preamp tubes and power tubes. Preamp tubes are smaller and usually encased in a metal cover. Power amp tubes are bigger and exposed. Both tubes are important for the overall sound and tone of your amp.
The preamp tubes are the first transitional part of the amp. They receive the signals directly from your guitar’s pickups and transfer them to the power tubes, which send the sound to the output speaker of your amp.
So, in short, the preamp tubes are the first step in amplifying the sound but don’t amplify the sound too much, while the power amps have much more, well… power.
How long do tube amp tubes last?
There is no set expiry date on your tubes. Tubes can last years and years or just a few months, depending on how much strain they are getting. If you play with the master volume high and the gain turned up, your tubes will have a much shorter life span. As a general rule of thumb, you should replace your tubes at least every 10,000 hours.