Tube Amplifiers
Aaron V asked:

i recently re-tubed my amp and the volume while pushing hard, I noticed a bright flash from one of the valves. What does this mean?


2 Comments so far

  1. Dave S on July 1, 2009 12:42 am

    did you know what you were donig when installing the new tubes?

    if so, could be just a bad tube…
    try another

    also search and then post at message boards if you dont find anything….they may have a good answer for this question.

  2. lare on July 1, 2009 6:35 pm

    when too much current passes the plate (anode) it heats up and can glow or even get bright. we used to tune old AM broadcast transmitters by looking at the glow on the tube plates. those tube were force cooled so they could run hot.

    another kind of flashing light can come from a ‘gassy’ tube. generally tubes get gassy after long periods of operation causes contamination of the cathode, but a new tube could be defective too. after warm up, ions (not electrons) start to move in the envelope as if they were gas molecules and can give off a glowing discharge. In many tube designs a “getter” is used after the tube is sealed to chemically bond with any gas that was not evacuated by the vacuum, and if the getter process didn’t work properly the tube would be gassy.

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