Tubes that Glow Different


DOes it mean anything when tubes on my amp sometimes glow less bright than other tubes that are of the same "batch"? I have some 6SN7s where one of them isn't glowing as brightly. Sometimes, my output tubes also differ in how they glow... the longer I leave the amp on, the more the same their glow becomes...what's up with that?
128x128dennis_the_menace
Two questions: 1-is your amp getting enough fresh air? 2-when you say "longer", do you mean 5 minutes or 2 hours of hard playing? Your only real worry should be if one of the tubes glows very brightly-your bias may be off.
Sorry, just reread my post, and realized it didn't make sense.

The longer I leave the amp on, the more the tubes glow the same brightness...

it's just this one 6SN7 that isn't glowing as brightly. The 300bs start off at different glowing brightnesses, and then become more alike as the amp stays powered on...

It's a VAC 70/70, and it is self biasing...
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