I mentioned the "Blue Glow" from the 6P3S-E tubes in my SSE in another thread. What I didn't really notice before is that they sort of act like a VU meter, but different areas of the blue glow seem to be associated with different audio frequencies.
Pretty cool, I think:
Tubelab SSE + 6P3S-E Tubes = Blow Glow Light Show - YouTube
Sorry for the bad camera work and sub-standard audio. Try to watch it before the copyright Nazis shut it down.
Pretty cool, I think:
Tubelab SSE + 6P3S-E Tubes = Blow Glow Light Show - YouTube
Sorry for the bad camera work and sub-standard audio. Try to watch it before the copyright Nazis shut it down.
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That's very interesting. I've never seen them do that, but my only experience with the 6P3S-E is push pull, not single ended.
jeff
jeff
I can't really imagine why it is happening because my knowledge of how a tube works is rudimentary at best, but I don't recall ever seeing video of this so I thought I would capture it and share it. I am very glad that you have all enjoyed seeing it. 🙂
AND Vitamin D
AND an excellent source of Vitamin D, which they say is a mitigating factor in The COVID.
AND an excellent source of Vitamin D, which they say is a mitigating factor in The COVID.
It's not actually UV. There are two sources of blue light from a tube.
Some tubes, especially some new production stuff have residual gas left inside, or impurities in construction that get released by heat. These can ionize creating a light that can vary from pink to purple to light blue. This light comes from inside the plate structure, and can cause unintended operation, including a runaway meltdown if it's bad enough.
Some tubes have a very good vacuum and some high speed electrons miss the plate or go through the holes and strike the glass envelope. The glass envelope often contains some impurities, primarily cobalt that can phosphoresce. This glow is on the inside of the glass itself and is harmless. It is also an indication that the tube has a good vacuum inside, but the glow will wane as the tubes wear. I am including a picture of the Russian KT88's in my SSE. This picture was taken when I got the tubes. The glow also danced to the music when the amp was played loud. Ten years later the tubes still work, but no longer glow blue.
I am also posting a picture of a BAD tube that has glow from inside the plate structure. This is a 211 tube running on 1000 volts. The glow caused enough current flow in the wrong direction to blow parts in the amp.
Some tubes, especially some new production stuff have residual gas left inside, or impurities in construction that get released by heat. These can ionize creating a light that can vary from pink to purple to light blue. This light comes from inside the plate structure, and can cause unintended operation, including a runaway meltdown if it's bad enough.
Some tubes have a very good vacuum and some high speed electrons miss the plate or go through the holes and strike the glass envelope. The glass envelope often contains some impurities, primarily cobalt that can phosphoresce. This glow is on the inside of the glass itself and is harmless. It is also an indication that the tube has a good vacuum inside, but the glow will wane as the tubes wear. I am including a picture of the Russian KT88's in my SSE. This picture was taken when I got the tubes. The glow also danced to the music when the amp was played loud. Ten years later the tubes still work, but no longer glow blue.
I am also posting a picture of a BAD tube that has glow from inside the plate structure. This is a 211 tube running on 1000 volts. The glow caused enough current flow in the wrong direction to blow parts in the amp.
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Some nice glow!
I tried my brand new pair of 6L6GC in my SSE last night and they also have the blue glow. I am a bit surprised by that, actually.
I tried my brand new pair of 6L6GC in my SSE last night and they also have the blue glow. I am a bit surprised by that, actually.
I think the blue glow champion is the Bendix 5992.
I have never seen one that did not glow robustly, and in my experience, it never fades. I have one 5992, one of the Pioneer / Eclipse super old timers that barely has any getter left, and it glows like a new one.
Sadly, they have become quite expensive because of the audiophile hype. My measurement equipment is pretty crude, but the 5992 always seems to measure out with more distortion than lesser 6V6's. But they sure do look good, and last forever.
I have never seen one that did not glow robustly, and in my experience, it never fades. I have one 5992, one of the Pioneer / Eclipse super old timers that barely has any getter left, and it glows like a new one.
Sadly, they have become quite expensive because of the audiophile hype. My measurement equipment is pretty crude, but the 5992 always seems to measure out with more distortion than lesser 6V6's. But they sure do look good, and last forever.
I have noticed that Chinese tubes rarely have blue glow on the glass. Many older US tubes do, but you need to run them at high voltages. The most blue seem to be found in Russian tubes, so I'm guessing it has to do with the glass itself.
Interesting that you say that, George. I've never had Chinese tubes with blue glow either, but the new 6L6GCs that I mentioned earlier are Chinese. They are "Preferred Series" (house brand) tubes from thetubestore.com, which were made to order by Shuguang. Preferred Series 6L6GC Audio Tubes - www.thetubestore.com
I'll post a photo later.
I'll post a photo later.
I haven't really used many Chinese tubes. I recall the small coke bottle 6L6GC's would glow pretty good. Best I recall, those Chinese 6146B's I used in the SSE gave a good blue glow.
I agree the Russian tubes are most likely to give a good glow. I had ( have ) some of the coke bottle 6L6GC's that Tung Sol markets, and they look terrific at about 450 volts across the tube. Most of mine went to gas sitting in the boxes though, so I am sort of sour on them. They weren't cheap tubes.
I agree the Russian tubes are most likely to give a good glow. I had ( have ) some of the coke bottle 6L6GC's that Tung Sol markets, and they look terrific at about 450 volts across the tube. Most of mine went to gas sitting in the boxes though, so I am sort of sour on them. They weren't cheap tubes.
When I finished my TSEII, I was pleasantly surprised myself when a pair of Chinese 2A3s (really 300Bs with a 2.5V filament) exhibited that mystical blue glow. The pic below is of said amp in its original "breadboard" state.
And cogitech: When I first read the thread title I had visions of sparks, smoke and shards of glass - not unreasonable given George's well-documented antics on the forum. I'm pleased your light show was of the more, er, "functional" variety. 😀
And cogitech: When I first read the thread title I had visions of sparks, smoke and shards of glass - not unreasonable given George's well-documented antics on the forum. I'm pleased your light show was of the more, er, "functional" variety. 😀
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I have a pair of dual plate Chinese 2A3's in my TSE-II. Despite running on 370 volts they don't glow at all. They are probably 20 years old, but had never seen power until I put them in the TSE-II. I got a bunch of 300B's, 2A3's and 845's from Stan back when he first started selling Chinese tubes. They were real cheap, like $28 for an 845.
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