对于96年版的300B,STEREOPHILE的原文如下
happened to meet Western Electric's owner/director, Charles Whitener, at the London HiFi Show last September. I told him about our amazement when we found out that the WE tubes clearly needed more hours of burn-in than the others; and about our confusion over the first pair of WEs, which were supposed to have been burned-in at the factory but didn't sound right until after we'd given them another 200 hours. Whitener confirmed our guess: Other than a standard 24-hour test, the first pair of WEs hadn't been burned-in at all. WE never does that. (The guy who told me that they do no longer works at WE.)
Whitener also explained to me why WE tubes take a longer time to break in than other brands. As in all other makes, the coating (footnote 1) on a WE300B's heater contains barium oxide and strontium oxide, but WE does not add the usual small amount of calcium oxide. The calcium acts as a kind of pep pill in activating the barium, meaning that calcium-doped 300Bs reach their peak rather quickly, within 100-200 hours, and thereafter (according to Whitener) degrade slowly. Though the WE takes considerably longer to reach its top level of performance, its absence of calcium is said to maintain that high level over the tube's entire lifespan.
As of now, Western Electric suggests a minimum of 500 hours' burn-in, that recommendation to be included in their future literature.—Peter van Willenswaard
