This is official information from the manufacturer, certified by documents. Read please. Sources: Katsnelson, B.V., Larionov, A.S. Domestic receiving-amplifier lamps and their foreign counterparts. - M .: Energy, 1968. - 544 p. - 60 000 copies   In the USSR, an analogue of ECC83 or 12AX7 was: their functional analogue of 6Н2П (6N2P), By 1995, four existing 12AX7 / ECC83 production lines remained in the world: EI [sh] (Serbia), Sino (China), Tesla (Czech Republic), and the Russian Reflector plant (Saratov), ​​which began producing three differently different versions 12AX7 on request American Wholesalers [1] [13]. All of these lamps were inferior to the Western European ECC83: the Chinese had a short service life, the Serb ones had a higher microphone effect, and the Russian ones had increased distortion like the old American 12AX7 [1]. By 2000, the Chinese plant ceased production, and the plant in Serbia, despite the international embargo, survived and managed to improve the quality of the lamps [13]. The Slovak company JJ Electronic [en], which traded in the United States under the Tesla and Teslovak brands, managed to set up production at the Chadze plant not only for the base 12AX7, but also for an exact copy of the improved ECC803S [13]. Kaluga plant "Voskhod" by 2000, released on American orders, seven different options 12AX7, in the same year began the supply of "guitar" 12AX7 production "Svetlana" [3]. In the 2010s, Russian-made lamps are sold in the USA under the brands of local dealers and under the classic brands Genalex Gold Lion [14], Mullard [15], Tung-Sol [16].