is a good start....he also has many, many links to other sites.

http://www.one-electron.com/filing_cab.html

I have found another interesting site:

• tubebuilder.com/schematics

http://www.one-electron.com/FC_Consumer.html

http://www.triodeel.com/dusty.htm

http://www.bonavolta.ch/hobby/en/audio/audioel.htm

Dave