I purchased this tube to put in my Blackstar HT5 after having read the forum BCQ to replace the original Sovtek 12AX7WA
this lamp is badged sylvania in January 5751 USA (among other lamp used in military missiles and aircraft hunts)
I do not know his year of production but it has the same print as the picture above
I found the lead channel of vitamin HT5 too (the two coins of the stroke of half the gain knob never served me any) and clean a little dull especially a low volume (ie below the half at home so the clean does not really seemed fun)
The idea was a lamp with moin gain => successful bet
I think I lost a little but a power clean?? but who cares ...
the sound is very good, well balanced the amp seems more civilized and the balance between the two channels is much easier to find ...
The crunch is more beautiful in any case I like it better and easier to settle (cf. my opinion)
I also bought a General Electric OUR 12AX7WA I'll try another time.