A Vacuum Tube Primer

Glass, metal, lots of little parts... tubes are subject to mechanical problems and are not meant to last a lifetime. The harder you work your tubes, the faster they wear out. Plus, there are a number of other factors that make tubes one of the easiest and least expensive “fixes” for your tube amp.

1. Tubes are subject to vibration damage. The inside of a combo tube amplifier is a super-abusive environment for tubes because you crank up the volume, create a huge amount of sonic vibration, directly couple the tubes to the chassis of your amp and then stick the chassis inside the speaker cabinet!

2. When tubes operate, the metal parts on the inside of the tube begin to glow. That means that they are really hot, like molten metal. When metal is heated enough to glow, it gets soft. Excessive vibration can create a situation where the metal becomes fatigued or stressed.

3. If you are at a gig with your amp, you run it hard and then quickly take it outside and throw it in the back of your car while the internal components are still warm and soft, the bouncing around while you are driving can cause damage to the tube.

4. The reason that it is called a “vacuum tube” is that the air is sucked out of the inside of the tube when it is manufactured. This creates a “vacuum” inside the tube and this lack of oxygen allows the metal parts to heat up without actually burning. If the tube develops a leak, or the seal is broken air will leak back into the tube and the components could smoke, smolder or burn.

5. Tubes are inexpensive compared to transformers, speakers, etc…and a lot easier to replace!

6. When one tube starts to go, it drags the others down with it, decreasing the overall efficiency of the amp, which adversely changes the tone and reduces sustain.

7. You can keep spare tubes with you in case something happens at a gig. With Groove Tubes you can even make sure that you have a spare power tube set with the exact same rating.

8. Many manufacturers have started producing small, inexpensive tube amps. While many of these are really cool, sometimes a manufacturer will cut corners on the tubes that come in the amp. Groove Tubes preamp and power tubes can really punch up the performance of these amps.

9. With the easy-to-understand descriptions of GT preamp tubes, you can experiment with different styles and types to achieve a wide variety of different gain structure and tone.

10. Audio troubleshooting. Change tubes if your amp experiences any of the following:

    1. Loss of tone, clarity, sustain and harmonic richness.

    2. Poor output-level balance.

    3. Lack of midrange punch and definition.

    4. Rattling, whistling or humming.

    5. Feedback or metallic sound on certain notes

    6. Weak sound and power loss.

    7. Or, if your want to experiment and change amp tone characteristics.