I avoided this thread, thinking it would be a bunch of puffery but I was glad I finally read it. Lots of very good points made here, none of which I think I'd disagree with.
JJ supposedly makes *very* good modern production tubes. Most of the EH line is said to be very good as well. The 6922 made by JJ (aka. ECC88, 6DJ8, etc) is supposedly a very nice and very reliable 6922. Their 12AT7 is also suppose to be very good and their EL84's, EL34's and KT77's are suppose to rival some of the best NOS tubes (of course everyone has different preferences). EH's KT88s & 6550's are apparently the bomb.
JJ's are made in the old Tesla factory in the Czech republic iirc. KR Audio is also made in Czech Rep if my memory serves me. I'd rather spend $525 for a pair of KR 300BXLS than $800 on WE 300Bs. I choose the same if they were the same price. KR Audio had some issues, from what I read, when Dr. Kron passed and the company was sold until things resolved and are now hunky dory again.
A good thing about being a tube DIY'er is that I can choose readily available good quality and inexpensive NOS tubes for building my circuit, rather than hoarded, bid up, uber rare and uber expensive NOS tubes.
Good example, when reading Morgan Jones's Valve Amplifiers* one will find a laundry list of 6SN7's and their equivalents along with a detailed study of their performance in a superb circuit. The resulting distortion and it's spectrum is listed out to the 6th harmonic (after which its in the noise floor of the measurment equiptment). He notes that certain 6SN7's rise above the rest within that same name, also how some of its equivalents don't measure up, some do, and some perform better than the ordinary 6SN7's. One of the uber performers is an Loktal equivalent, that performs at the top of the list. It is easy to come by (since Loktal was never popular) and super cheap, even today. He also shows the blatant superiority of the 6SN7 family to the 12A_7 family, some others and even the 5687.
When he was describing variation between tubes within the same designation (i.e. 12AU7, 6922, 6SN7) he describes how 6SN7's were made by hand but manufacturing of the 12A_7 family became much more precise, which much less variation from tube to tube. He makes a funny comment about the 12AU7, which I will paraphrase. The 12AU7 is suprisingly consistent from sample to sample; its surprisingly poor.
* There is a multitude of fantastic tube information in the Morgan Jones book. Even for the non DIY'er but tube enthusiast, I cannot recommend the book enough. Morgan covers valve selection in detail, provides studies to support his claims, describes tube construction in dissecting detail and thereby shedding immense light on why they sound different, perform different, etc. He adds a lot of history about the production, rationale, the production reason behind a tube, the goals of that design, etc. For instance, the 12AX7 was designed when feedback was becoming commonly accepted and therefore purposely accepts higher distortion to acheive higher gain (needed for feedback) whereas early tubes were designed for low distortion and feedback was sacrilege. Altogether there are a number of chapters that don't require super technical aptitude to digest and shed light on tubes, how they work, what makes some better than others, how to pick them, what to watch out for with aging NOS tubes, etc, etc.
Then you might even find yourself reading the basics of tube gain stages and start understanding what makes a good amplifier and what makes bad ones, or at least what their various trade-offs are.
