Hey, I was going over your Electronics 101 and loving it...I just built a period correct 100W 1968 Marshall Plexi based on the 1959 circuit (I ve been on a relentless 2 year Eddie Van Halen 1 tone hunt) and now I m trying to learn more about it. Anyway, I really learned a lot, I m amazed. I like understand the voltage doubling rectifier now and how the main filters (twin 100uf 250vdc caps) along with the choke (transformer) create what appears to be DC from AC...sooo cool.