I've read that dozens of times for over 4 years now.
You'll notice it is not complete and the type of amp and components used is not listed. Not listing the components means his opinion is based on a huge unknown which really clouds the truth.
Valvo, Philips Miniwatt, Telefunken smooth plates, Lorentz, Mazda, Siemens triple plate, Tung-Sol, Heintz and Kaufman and that’s just off the top of my head.
I was hoping for people to indicate which types or brands they have actually tried and enjoyed.
This is a partial list of possible variants which could all sound different depending on the manufacturer:
12AX7A, 12AX7WA, 7025, 7025A*, 12AY7, 5751*, 5751WA*, 6057, 6072*, 6681, 7494, 7729
So yeah I’ve done some legwork already. I listened to at least 50 different types of 12AX7 and derivative tubes in one amp alone. And that was only the 12AX7's.
Mitch