Hey-Hey!!!,
Yes I have. Built with 6AK5, 6AU6, 12BY7, 12GN7, 6AH6, 8136. Missed a few, but the slightly more complex looking cascode works better. Tread Ec2 like the pentode's g2, and you're off. the g2 being in parallel with the plate does funny thigs( I think ) to the constant current out of the cathode circuit. The cascode is a series afair, and the pentode is a parallel. You still need a good g2 supply...
regards,
Douglas