When I first started building tube gear back in the 70's there was no internet, and indeed there was not much interest in tube gear. Solid state pretty much ruled and there were only a few commercial tube amplifier manufacturers and tube diy enthusiasts.
Tube design knowledge came mostly from libraries, I used to spend many afternoons in the State library, requesting electronic design books from the bowels of the archive basement.
Most of these books are lost now, although there are still some references available - The Radiotron Designers Handbook by Langford-Smith , The Mullard Design "green" book, the GE book, Morgan Jones work, etc.
I also had some mentors who were building amplifiers and were happy to show me their work.
But mostly my knowledge of how to build tube preamps, and what makes them work really well came from building many hundreds, perhaps in the thousand , of actual circuits.
Only from this approach does true knowledge and experience come, its called hands on, and a few electric shocks through those hands over the years!
Today, there's more talk than hands on, the internet forums are full of gurus and experts . You can get an opinion on just about any audio topic.
But its just OPINION. Anyone can digest a terabyte or two of digital audio and then re-sprout it as hard gained knowledge , but its not realized or experienced knowledge, its just re-hashed opinion.
Im my opinion (!!) 80% of what you read on audio forums these days is merely opinion, there's very little actual knowledge , and extreme caution should be exercised in believing what you read.
The internet is a wonderful device and a source of great knowledge, but discrimination and common sense is needed to sort the chaff (opinion) from the wheat (knowledge).
Enough said, I found this pix on an old hard drive the other day when looking for an old preamp design .
It featured in a Singaporean book "Marques of Distinction" . "A collection of the most beautiful photographs of audio products in one volume"
double click to enlarge.
