Electron tube 6P1P-EV (6П1П-ЕВ) from manufacturer SVETLANA, St. Petersburg (RU). A quality long life soviet output tetrode with improved mechanical strength. Not less than 5000 operating hours when running under prescribed conditions. It is direct replacement of the chinese 6P1 tube. This tube is a part of many amps which are nowadays produced in China: Nobsound MS-10D MKII, Nobsound MS-10D MKIII, Cayin MT-12N and many others. 6P1P-EV does not have any direct european or american replacement. It is very close to the EL90/6AQ5, but it has a different pinout (9-pin vs. 7-pin). New old stock, directly from the factory packing. Made in the 70's and 80's.