Oh man those are gorgeous. Moar plzz. Are those 300bs getting gassy inside or are they just painted to look like that. The blue glow looks like they might be wearing out.
Some of these pictures were taken with my old camera, which could not do long exposures worth a crap. If you look carefully at the 300B mesh plates, the glow in on the glass. This is a phenomenon known as tube florescence, which occurs because of impurities in the glass envelope. Electrons that don't make it to the plate will strike the glass and cause the impurities to glow. You'll usually see this in line with gaps in the plate structure. In the case of the 300Bs, it's probably due to the meshed plates. Now if you see blue or purple haze inside the envelope, especially in and around the cage (behind the plate), then you likely have a gassy tube:
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(not my amp, but an extreme case using a 211 transmitter tube)
Some more tube glow for you. These are the vintage 8417s that came with this amp. My dad bought them in the early '70s for < $1 each.
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Here is my ST-70 right after the rebuild some years ago:
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This is a close up of a strange florescences that happens around the screens of SED's EL34s. It has something to do with the coatings the SED uses on their screens.
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This is Tubelab's SPP. I was one of George's "beta testers" for his kit, so I tossed it in this lock box. I use it in my shop:
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Here it is during a bench test. There were some issues with the design at first:
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More pictures and info here:http://www.knizefamily.net/russ/category/electronics/tubeaudio/