I have a brand-new pair of Valve Art tubes, and they sound OK but have a very peculiar symptom. One sounds fine but the other makes intermittent pops, like a Geiger counter sound. If you rotate the tube 90o so that it lays horizontally, it becomes quiet. But stand it up and it starts popping again.

This is a consistent symptom, and is perfectly repeatable. Give it some signal and run it about a half hour and the popping goes away. Not fully, but the popping is reduced a great deal. You won't notice it when there is something playing, but in between passages, it's there again.

So I need to do something else. I probably should have sent this one defective tube back, but I didn't. It has maybe a couple hundred hours on it now, so I wouldn't feel right sending it back. I had hoped it would go away, but it hasn't. So I'll make it "go away" by buying new tubes.

I have a question. Do all 2A3's have a gas that glows blue inside? Or is it just Valve Art tubes? That's probably a very naive question, but I never noticed it on other 2A3 tubes and so I was wondering if maybe I just didn't pay attention.