One thing is certain. Most mass produced items today are made a cheaply as possible, and many times quality is allowed to suffer for the sake of profit. There was a time in the U.S. and other nations when cost was factored in but also balanced with quality being the driving force.
Does this apply to all old production tubes? Probably not, but it surely applied to many of them, and the results speak for themselves. I collect, use and sell a lot of vintage gear from tubes to guitars to amplifiers. I use NOS tubes in my Engl Fireball 100, Mesa Rocket 4Forty and my brownface Fender 6G3.
When I was younger I tried all the modern 12AX7 12AT7, EL84, 6L6GC, and EL34 types. JJ, Sovtek, EH and Ruby always performed pretty solidly. Mullard and Tungsol performed terribly. Even the Chinese high gain Shuguang tubes were better IMO. But I have had the best experience with the various NOS units I've had the pleasure of owning, and after 11 years of research and forum hopping as well as experimenting, I've happily persuaded others to give old production a chance. Most people are very happy with the results. I use a custom DIY curve tracing kit in combination with a Hickok 600A serviced and calibrated by Radiola Guy, who sadly no longer performs those services.
I can tell you that Brent Jesse is one of the greatest guys to talk to and work with. Anyone who values his opinions and knowledge is ok in my book. If I don't have what someone is looking for or think he could help them in any way I can't, I would refer him in a heartbeat.
