Ultralinear, as the name implies, is more linear than triode. General electric published curves with typical screen taps that illustrated this. I wanted to get 100 watts (I got 120 watts) out of a quartet of EL-34's. At 50 Watts per pair that surpassed the typical 35 watts per pair that Dynaco, Marantz and others obtained. I biased the amp in such a way to get 10,000 hours tube life which has now become a benchmark, though one must be wary of those who state their tube life based on other people's amplifiers.
This brings me to report a similar situation with Chinese made fluorescent lamps which are rapidly coming to the surface in our energy strapped world. Here in California we can get them 4 for one dollar thanks to Southern California Edison who subsidizes the cost to these ridiculous levels. The Chinese have decided that all fluorescent lamps last 10,000 hours because that is the typical lifetime of a well made Sylvania or General Electric lamp. Sylvania in particular worked hard to achieve this lifetime through years of chemistry and lifetime tests. The Chinese claim the same lifetime though their's is much shorter. I have had some go out in 10 hours and none of mine have lasted 10,000 hours. In another lamp the electronic ballast failed, melted the plastic and could have caused a fire.
