The 12B4 tube has a lot of followers. They can swear that this is the most transparent sounding preamplifier ever. I will hold my thoughts about this claim. However it’s a simple, minimalistic and offers the shortest signal path possible.
Due to it’s internal construction and typical characteristics the 12B4 offers almost no PSRR. This calls for a regulated power supply. The tube loving path is of course a tube voltage regulation. A modern approach is to combine the voltage stabilization with a solid state constant current source. Here is a general idea of how this might look like:
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0D3 does not stabilize at 150 volts?