Hi, I have completed my 20W Lead and Bass ; it works on first power on, the lead channel has a great clean and a marvelous cranked sound. I have only a slight problem on the bass channel only when cranked, I hear a crackling noise only on low E notes (6th string empty, or 5th string on 7th fret) but not on any other note. The noise is encountered on any of the two jack inputs, but the volume is lower on the bottom jack (as usual). It must be some kind of resonnance ? but I don't know where to look for. I have checked the values and the solder joints. Any other idea ?

Thanks, I will try that tomorrow

You never check enough .... Chris, you were right on
it was after all a dry solder joint on the capacitor between the tone pot and the volume pot on the bass channel ; after resolder, the strange noise is gone 

the guts of the completed amp :

I want to hear some sound clips of that bad boy.  That's the next amp I've been thinking about, but I"m not sure if I can handle a solid state rectifier.  Maybe I'll mod it for a tube rectifier (but then I'd need a different PT).