I'm in need of info on how to calculate biasing (from load line plots) of say a 12ax7 tube configure in local feedback mode I.E. Rg instead of going directly to ground connects to a node between Rk1 and Rk2 where Rk1 connects to the grid and Rk2 connects to ground. Instruction on biasing and gain calculation would be helpfull based around plate load charts.