Guess I spoke too soon. The one on the left channel just poof'd. Bad noises from the speaker. Sparks, pops, and clicks from the tube. Funky colors. Oh well. They were used, and I hadn't paid more than a buck or two for the pair. It was nice while it lasted - they were probably great tubes when they were new.
So I just ran the SED EL34s in there for about 15 minutes with no signal. The SED tubes have this weird blue glow around each screen wire when it gets near the plate. I've never seen anything quite like it. The VAs don't do that. No sign of any glow of the wire itself, though...tried both triode and UL.
rknize said:
Yes, that's normal. Every Russian tube I've ever had does the same thing. 6p14p, 6p3s-e, they've all got it. You can see where the electron stream strikes the inside of the plate. It glows a medium light-blue.
After the Xf3 popped, I went through my box of goodies. I found a pair of what looks to be SED EL34 (not Winged C). Boy, these things sound good! Screens look fine, and they have the typical Russian blue stripes on the inside of the plates. Maybe I can get some photos...
The photo doesn't really do it justice. You need to be able to move your head up and down while you peer through the holes - they're so darn small. Anyway, you might be able to make out a little of what's in there...
Yep, those be dem. The electron flow is directed onto the plate by one of the grids (control? suppressor?) and the lines of the resulting beam are somehow magically focused. Lots of these Russian tubes make a nice sharp pattern - you can really see the shadow.
I edited my post up above yours with a photo of my tubes. It shows kinda the same thing as what you are seeing.
I edited my post up above yours with a photo of my tubes. It shows kinda the same thing as what you are seeing.
Just thought I'd let you know that I ran the Valve Art EL34s in triode for several hours without any signs of screen glow. These also have the blue marks on the inside of the plate. I just never noticed before because the slits in the plates are so small. A pentode thing, I guess.
That picture is with the SED tubes in the Dynaco. They are even brighter in the Simple SE.
That picture is with the SED tubes in the Dynaco. They are even brighter in the Simple SE.
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