- for details on transconductance amps                                                  Ultrasound 

- an analysis on the audible differences between solid state and tubes     Tubes Vs. Transistors - Audibly Different 

- considerations on sound and audio equipment by Arthur Salvatore       high-endaudio.com 

- the store to buy the Semisouth Power Jfet and other components         SISRAM

- excellent site for tube datasheet                                                           Frank's Electron tube Pages 

- excellent site for the presentation of various audio circuits                    The Tube CAD Journal   

- site of the legendary Kiyoaki Imai and Audio Tekne products             Audio Tekne  

- excellent source for DIY lovers, by the sound guru Shinichi Kamijo     Evolve Power Amplifiers  

- the D-I-Y site of the volcanic Nelson Pass                                          Pass D.I.Y. Home of DIY Audio  

- one of the most beautiful audio blog                                                    TWOGOODEARS

- an electronic and audio link list                                                            ultrajosh.com-tubeamp

- tube (etc.) datasheet                                                                           Duncan's Amp Pages 

- designs of historic audio equipment                                                     Consumer Audio Information   

- great site for tube lovers and DIYourselfers                                        World Tube Audio Portal

- forum for DIYourselfers                                                                     diyAudio.com - audio projects 

- German site with photos of Telefunken grinders, Philips Valvo tubes   Jogis Roehrenbude

- site for downloading programs for DIY speakers and other                Steve Ekblad's Free Audio Software  

- for details in all branches of science                                                   101 SCIENCE