Tube Preamp Schematic of Tubepreamplifier with WE417A or 5842 Triodes
The Western-Electric 417A (a.k.a. 5842) has a very high transconductance, a low internal resistance and a high plate-current. You need good gridstoppers with the 4 grid-pins to avoid parasitic oscillations. The Anode-resistor has to be a 5-Watt-Type, try the Kiwame Carbonfilm-Resistors, a Mills Wirewound will have no chance.