Have not used em but heard they are rugged and maybe little bright to some people (I never know how much to put into such reports). My understanding is that most Ei's (Yugo/Serbian)floating around now are not actually EL34's but a true beam tetrode and more rugged. Ei made a EL34 but this tube is not it. Sound dif. Many of the 6CA7s were relabled by the distributor (Orion?)Think I read about it at Jim's Citation Amp and Vacuum Tube Page. Try there for more info, check it out before you buy.
Any info on fat bottle Ei tubes?
I saw a ad on Ebay for quads of Ei fat bottle tubes. The ad stated more output power. When I inquired as to what made these tubes have more output I was told that the bottle design had something to do with it. My question to old tubeheads is: Can a tube be made to put out more than it's rated power(EL34)? Also what would a fat bottle design have to do with power? It should be a internal design that would make all the difference no? Just curious as I am somewhat new to rolling of those magic bottles. Thanks,