NOS tubes

My perception of this is that NOS tubes were manufactured in the hey day of tube use in TVs, Radios, military equipment, etc. etc.  Because they were so essential to, in many cases, sensitive circuits, those tubes were manufactured to very strict, exacting standards leading to the coveted sound of many NOS tubes.  Interestingly, it seems that specific NOS brands have a universally recognized sonic signature.  To whit RCA clear tops are, well, clear and dynamic whereas Mullards are often considered as warmer and more forgiving in sound quality

I am not in any way an expert regarding tube history so I welcome others to correct me if my understanding is in error.

I use new production Gold Lion tubes sourced from Ron Sheldon's Cryoset store.  In my Modwright Signature mod. SACD player I use NOS Tung Sols as Gold Lion does not make 5687s.

My understanding was pretty much EVERY re-issue tube made today is made on the exact same manufacturing equipment they used back in the day.I don’t mean similar I mean complete refurbisment of the old gear.Even with advancements in metal purity I can’t see the NOS and reissues actually sounding any different..

@freediver  No argument from me about what you said above. If what you say is true, why all the fuss about buying NOS tubes rather than current production?  Because NOS adherents will use numerous adjectives to describe the sound of their gear with a particular NOS tube vs. another NOS tube, while bemoaning new production, I assume that they at least see something unique in their production and that it is not just a nostalgia movement for things from the 50's and 60's.