Mattijs DeVries Website
Excellent English language tube D.I.Y website, many articles and designs, Parts for sale, HIGHLY Recommended
Jim DeKort's VT52 Website
Another excellent English language website featuring many DHT and triode based projects. Very comprehensive.
Fred Nachbauer Tube Site
Sadly Fred is no longer with us, but his site and many interests live on. Something for everyone from beginner to expert.
Ulrich Haumann's Hi-Fi Site
Mixed German/English website dealing with DHT and plasma tweeter design...