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Vacuum Tubes for Guitar Amps

For a guitar player tube amplifiers definitely represent one of the keys to be taken into account in the search of the ideal tone of an electric guitar. That’s right! Most guitarists believe that no other amplifier can reproduce the warmth and personality offered by tube amps: their power, their volume, their distortion...

Although the pre-amp tubes do amplify the signal, for it to really sound as we wish we need the power tubes to come into play, which will strengthen the signal coming from the pre-amp.

These power tubes influence the sound of the amplifier, since they are in charge of amplifying the signal that comes from the pre-amp, being able add distortion to it, noise... giving it its particular tone of sound, basically.

There is something that we must take into account: this type of tubes that we will use in our amplifier must respect at all times the type of tubes that the amplifier had as standard. It is necessary to change all the power tubes and make the bias adjustment, because with this adjustment we will ensure that the power that passes through each tube is the same. That is why we also recommend that the power tubes should be paired.

The amplifier tubes that are mostly used for preamps are 12at7 or ecc81, 12au7 or ecc82, 12ax7 or ecc8. While the most used power tubes are the EL34. 6L6, 6V6, EL84, KT88, KT66, 5881... For example:

  • The KT66 is a well-known power tube that works in the "push-pull" configuration that the Marshall amplifiers of the mid-60s used to mount. It produces a round and thick tone of vintage aftertaste.
  • The KT88 is used more in high fidelity audio amps than in guitar amplifiers because of its high power and low distortion. You could see it like a larger variant of the KT66. It is one of the largest in its class and one of the most voltages supported, up to 800 volts.
  • The 12AX7/ECC83 is a common tube in preamps, from medium to high gain and with a linear frequency response.
    At Fanatic Guitars you can find a wide variety of Ruby Tubes, a brand of (non-producing) tubes that currently has the broadest tube catalog on the market. Ruby's most popular preamp tube is the 12AX7AC5 HG, high grade, low noise, with a sweet warm sound and very low mechanical and microphonic noise.

We recommend that you change the tubes of your amplifier when:

  • You notice that it is losing definition
  • There are abrupt volume changes
  • You hear background noise