So far tubes presented in this series were less known in the audio scene, cheaply and easily obtainable. Now it's time to also go to the other extreme and to present some of the rarer kind. I'll start with the tube many of you probably waited for, since I'm known for using it quite a lot. The Telefunken EC8020.
This is my all time favorite of the indirectly heated tubes. This tube has been developed in the 60ies by Telefunken. As far as I'm aware no other manufacturer ever made real EC8020s. There are currently manufactured tubes which are claimed to be close in parameters, namely the russian 6C45. While it might come close in terms of transconductance it is light years away in terms of stability of parameters, quality of manufacture and most important sound. The only tube which comes close is the WE437. But for me, the Telefunken EC8020 is the queen of the small signal high transconductance tubes.