Crate Vintage Club 20 gives a free light show

[brendo613]

My Crate Vintage Club 20 (VC2110) sounds loads better with a new set of tubes: Sovtek 12ax7 in V1, EH 12ax7 in V2, and two fresh JJ EL84's in the power section. While the tone, response, and timbre are largely superior than before, I am perplexed by its latest behavior ... Exhibit A

What are your thoughts?

[brendo613]

I got curious and swapped the EL84's around; it is just the one tube that flashes.

Is it possible that the cathode and filaments are getting too friendly with one another?

[Steve Conner]

Some tubes just do that. The left-over bits of heater wire sticking out of the cathode flash at turn-on, then dim down as the rest of the heater comes up to temperature.

As far as I know it's not harmful. There have been several threads on it before, try searching the forum.

[brendo613]

I came off as a board newbie! My apologies; in my defence, I actually did find some pages mentioning this phenomenon, both on here and other boards - but they all appeared to pertain to preamp tubes exclusively. I thought that it might be of a little more worry for power tubes, but your theory sounds plausible. Odd - guess I just enjoy the light