general interest

http://www.pmillett.com Tube related pdf treasure and very nice well elaborated projects
http://www.jacmusic.com/html/diversen/guestbk-all-text2.html Guestbook of tube equipment lovers 
http://www.audio-creative.nl/ New initiative from tube guru Triodedick
http://www.tubecad.com John Broskie of course
http://www.mif.pg.gda.pl/homepages/frank/vs.html Tube data from Frank Philipse
http://www.DrTube.com Lots of schematics and datasheets of popular tubes
http://www.valvewizard.co.uk Very informative site for tube amp builders
http://www.valveradio.net/index.php/en/home/audio Nice improved tube follower to drive tough A2 loads
http://www.worldtubeaudio.com/directory/directory.htm  Everything you will ever need to buid a tube amp 


https://www.knifrauman.com/845 Jonte Knif 845 amp using Monolith's irons
http://www.audionote.co.uk/comp/trans/trans_01_tx_news.shtml We can supply magnetics for AN kits 
http://www.whammerdyne.com High end 2A3 amplifier using our products
http://www.werneracoustics.de  Professional amplifier builder launches website
http://www.vcllabs.com Professional loudspeaker and amplifier design including simulation
http://www.vinylsavor.blogspot.be/ Professional custom tube amplifier builder 
http://www.qobuz.com My favorite FLAC music streamer
http://www.jriver.com My favorite highrez music player
http://www.gydotron.com Also selling caps, coils and parts
http://www.tentlabs.com Reference quality DIY audio products
http://www.jacmusic.com/ Distribution of high quality tube amplifier related parts
http://www.emissionlabs.com/ High quality DHT tubes
http://www.kraudio.com/ High quality DHT tubes
http://www.diyparadiso.com/ Tube amplifiers, parts, transformers, outerlimit, 845 

personal pages

http://sarris.info Nice tube amplifiers and horn loudpseakers from Greece
http://www.bartola.co.uk/valves/ The search for the lowest distotion tube goes on ..
http://hiend-audio.com New tube DIY site from poland
http://www.audiodesignguide.com/ In case you are looking for a schematic ...
http://www.youtube.com/user/sarriscostas?blend=3&ob=5 A new 2A3 amplifier from Costas using our transformers: part I
http://www.triodedick.com A true reference for amplifier design, over 1000000 hits !
http://buizenversterker.zappsite.nl/ A very good start ...
http://dddac.de tube amplifiers, preamps, dacs ...
http://audio.fam-gelder.nl/ Ultra linear 813 amplifier
http://www.dhtrob.com very extensive information on tube amplifiers
http://www.vt52.com From very low power towards higher power
http://www.wimdehaan.nl/ Tube and hybrid designs