Tech info:
Jack Darr's Book (pdf's)Electric Guitar Amplifier Handbook.
Aiken AmplificationClick on "tech info"
Tone stack infoCovers 1, 2, & 3 knob, and variations of each
BOUNDS of tech stuffLearn some stuff with help from Duncan amps.
Screen grids in power tubesMore information about PP screen grids then you would ever care to know.
Valve wizardLots of random good info.
WOW - pdf's!A lot of old tube tech manuals.
Parts:
Octoparts if you are having trouble finding a part you are looking for.
NOTE: If ordering caps and/or resistors, I strongly suggest either Mouser or Digikey.Digikey Great selection - FAST shipping, good prices.
Mouser MASSIVE selection, good shipping, good prices.
Hoffman Amps GREAT place to buy amp building/modding/replacement parts - never had a problem.
Angela One of the BEST places to get Hammond transformers - they have other amp parts too.