Russian Triode/Tetrode/Pentode Vectored in Adobe Illustrator by Yukio Miyamoto
Presently the majority of new thermionic valves are manufactured in Russia or those parts of Eastern Europe that were behind The Iron Curtain. Such valves can withstand overloads through say a huge electromagnetic disturbance in a way transistors cannot. This apparently why certain regimes favour them over transistors. We can be sure the motivation was/is not the warmth and harmonics of audio reproduction in eye wateringly expensive HiFi equipment. Valves were developed in 1926 primarily to amplify telephony.