* Aiken amp's safety tips
             * Drifter amp's safety advice
             * Capacitor discharge calculator
             * Geofex' tube amp FAQ
             * Paul Ruby's amp building FAQ
             * Superb out-of-print book on guitar amps
             * Basic electronics explained
             * Valve theory explained
             * US Navy detailed electronics course 
             * Ampage discussion forum
             * The AX84 project and discussion forum
             * Forum for amps based on the Marshall 18W

             *Yahoo's JTM45 group
             * Tips, mods, etc for Marshall amps