NOS tubes

JAN refers to what you stated and built more rugged to meet their needs. 

  Your question has been answered. FWIT I have a small system with a Rogue RP-1, Had Inspire , Zu Omens, Schiit Yiggy , Thorens TT. Tube rolling is system , room , and taste dependent. Most go for polar opposite’s which is Tekefunken Vs Mullard. RCA  is a nice compromise. If Brent Jesse’s site is still up read the 12AU7 page description of how they sound. I think I’ve purchased about 10 pairs of          12 AU7’s playing with my Rogue. Cheers , Mike B. 

"built more rugged to meet their needs...."  Yes, that is often said.  But I think, at best, the JAN tubes were tested after manufacture to demonstrate they were up to spec to begin life, before being shipped out to the military. However, I have compared closely a number of tubes from the same manufacturer, one JAN vs the other not JAN, and I never saw any difference at all between the two in construction.  There ARE tubes with novel alphanumeric designations that replace common tubes, e.g., 6900 vs 5687, or RCA 5632(?) vs 6SN7, that really are built differently from their counterparts. 

buell, I have made my feelings about 12AU7s known here in past postings.  I don't like any of them. So I even avoid equipment that uses them, but if necessary, I replace them with either 12FQ7 or 6FQ7, depending upon the filament voltage supply. The only issue there is that the FQ7 requires twice the filament current as does a 12AU7. (For those who don't know, a 12AU7 can be wired for either 6V or 12V filament voltage, same tube; whereas you have to choose your FQ7 based on filament V. So 12FQ7 and 6FQ7 are different tubes.) I guess I would concede that in my experience with AU7s, the Amperex Bugleboy, real ones, are OK.

Like most military requisitions, they probably just double the price for the same tubes and stamp JAN on them. Nobody really follows up to see if they're more durable than commercial ones.