The tubes in your guitar amplifier have a limited life span and just like light bulbs, they may simply burn out or may lose power and become worn down through normal wear and tear.

It is recommended that all of the same type of tubes are replaced at the same time much like you would replace all four tires of your car in order to ensure even tone and wear. This is especially recommended for output tubes. Wear down of your tubes occurs gradually and you will notice a marked difference in performance and tone once they are replaced.

Matchless amps are cathode self biasing so there is no need to bias the amps. Simply pull out (not unscrew) the tubes that need replacing.

Warning: Tubes can so make sure the amp is completely cool and unplugged before you attempt to change the tubes.

The following is a symptom check list to determine whether or not it is time for you to replace your tubes.

Power/Output Tubes:

  • A low, rumbling sound
  • Generally sounds dull and lifeless
  • Need to turn up the volume
  • Blowing fuses

Preamp Tubes:

  • A high pitched whine
  • Crackling
  • Static-y noise
  • Microphonic, squealing, hissing or humming noise that occurs even when the guitar is not plugged in.

To quickly determine which preamp tube may be bad, take a pencil and gently tap each pre amp tube to see which one has a loud ringing or crackling sound. They will all ring to a certain degree but the "bad" one may be much more noticeable. Replace this one immediately.

Rectifier Tubes:

  • The amplifier is blowing fuses, this may be a warning sign that rectifier tube failure is occurring. The amplifier is drawing more electricity from the tubes in order to produce the same output.

Other symptoms:

  • Erratic changes in volume
  • Muddy bottom end, bassy, loss of note clarity
  • General amp failure
  • Crackle and static

Matchless amps employ JJ (formerly Tesla JnJ) tubes as stock tubes and you can purchase replacements here (link to parts purchase page). However, we recommend you purchase the best tubes you can afford and we encourage experimentation with different brands.

We recommend the following brands for the replacement of EF86/6267 tubes: Electro-Harmonix (stock), NOS Mullard, Siemans, Telefunken, Dario Mini-Watt. We recommend the following for 5AR4/GZ34 tubes: Chinese Sino, NOS Mullard, Phillips and GE. Please refer to the tube chart in your amplifier to identify the tube type.