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If you are in a 50hz area and the unit you are using only converts voltage, not line frequency, watch out for power transformer heating. A transformer works a lot harder at 50hz than 60hz and, depending on the core material employed and how close to the edge the design is for 50hz, it might heat up ...

That's what I was saying above. New production tubes do not necessarily sound bad. And there is a lot of play in the notion of what sounds "good"-- not to mention differences in equipment that skew how particular tubes might perform. Now as for longevity or reliability of Chinese tubes vs. Mullards....

1A is probably a nice conservative value. Make it a fast-blow fuse. However, a fuse is only a partial solution in a number of ways. They are slow to act and best for protection against shorted transistors and major mishaps. Best solution is to have enough power and never make mistakes! Tweeters have...

To me the sound the tube produces in the circuit is much more important than the branding on the bottle. Precisely my point. My design partner, jc morrison (former lead engineer at New Sensor,) and I are working on some pro gear built to insane standards like our hifi stuff and we will not be using...

, I refuse to tolerate any disrespectful posts towards others and request that you leave my thread. Don't leave, bluesman! Jeez, I was just starting to like the guy. I have owned about a hundred thousand tubes and I learn things about tubes on ebay all the time. Where else will you find thousands o...

Hey don't laugh, bro...I just saw an auction listing for a "17th century cast iron pot like the cowboys used to cook out on the range."

And a 1oz bottle of synthetic oil "ideal for Altec Lansing gear."

Learnin new shit every day on ebay.

Yeah, before the fact opinions, often distilled from internet ramblings written by folks who probably didn't actually hear what they are speculating about, is a problem. Hearsay and junk science gets passed along as gospel truth every day. With tube rankings, taste and particulars of equipment matte...

oh, and my .02? TF tubes, to my ear, are overrated... The tube tasting discourse takes place in an abstract space without any stable real world reference. Try to look this stuff up and you will be deluged with microfacts about copper grid rods, getter geometries, and other totally wacked out shizni...

To actually answer the op's question...No, there is no way to tell save learning how to identify tubes without resort to the paint/silkscreening. There are a lot of hints...glass molding quirks and, especially, the manner in which numbers are etched into the glass--e.g. RCA, GE, and Sylvania had dis...