It's possible to build a switch so that these 62NP tubes are interchangeable with 12AX7 (or ECC83). Instructions in this thread: https://www.diyaudio.com/comm

It's possible to build a switch so that these 62NP tubes are interchangeable with 12AX7 (or ECC83). Instructions in this thread: https://www.diyaudio.com/community/threads/6n2p-ev-vs-12ax7.321760/page-2 https://www.diyaudio.com/community/threads/6n2p-ev-vs-12ax7.... Pins 9 and 5 of the tube socket must be galvanically disconnected from the PCB. The switch is then interposed there.