Вадим, ну какие они эстрадные эти лампы, до войны-то?
In their monumental 1957 work "An Approach to Audio Amplifier Design", GEC Engineers W.I.Heath and D. E. Leakey, together with MO Valve Engineer G.R. Woodville said this of the KT66 valve:
"The KT66 has achieved a world-wide reputation in setting a standard of performance in its class.
Introduced in 1937, it was used in very large quantities by the military services in World War II because its efficiency and reliability and it has since become the basis of many amplifiers with output powers up to 50W.
It is widely used in domestic and industrial amplifiers connected in push-pull triode or ultra-linear circuits for outputs of high quality from 15W to about 30W."(
http://www.oestex.com/tubes/williamson.htm)
А про 6L6 можно написать еще больше. Это абсолютно прикладные вещи. Передатчики, телефонные станции... Ты прикалывешься по жаре или правда не знаешь этого?