You can bias a tube to operate class A, AB, B, or C just like a transistor.
Any amp you can build with an npn transistor has an equivalent that can be built with a tube. The big difference is there is no complementary device for a tube like you have with npn and pnp transistors.
Any amp you can build with an npn transistor has an equivalent that can be built with a tube. The big difference is there is no complementary device for a tube like you have with npn and pnp transistors.