IN YOUR EXPERIENCE ?? WHAT IS THE QUIETEST 12AX7 TYPE TUBE ??? 6072 ? Spiral Filament

The quietest 12AX7 tubes I had were selected RCA NOS from Andy at Vintage Tube Services

The quietest tubes I have heard are the McIntosh branded 12ax7 tubes that came with my McIntosh C2500 preamp.  Dead silent, even with the volume control at max, not a peep from the speakers.  Not sure who makes the tubes but my guess would be JJ?

5751, I don't recall the brand. Whatever Frank Van Alstine was putting in his modded-Dynaco PAS pre-amp in the 1980's. Zero hum, and just a hint of tube rush with the volume control at max.

I had a man on the inside at NASA maintenance in the 70s and 80s who provided me with a steady stream of Miltary grade 12AX7WA tubes, Sylvania and RCA, these are the quietest I.e., low noise 12AX7s I’ve tried although Telefunkens are not chopped liver. Even the low microphonic tubes, however, benefit from Herbies tube dampers. So, you’re never totally in the clear.

I use GE 12ax7s circa 60’s and 70’s in my phono preamp and they are dead quiet. I have also used Sylvania Baldwin green label 12ax7s and they are also dead quiet!

Telefunken and Hitachi made the best I've seen.

Picked up some Japanese NOS Telefunken's  for a song that are remarkably quite. 94db speakers.

I replaced the McIntosh tubes that came with my McIntosh MC2300 and replaced them with NOS Telefunken tubes from the 1960's. Big improvement. 

Shuguang Treasure black 12AX7LS from Grant Fidelity. Better than Telefunkens and dead silent. I use them in my phono amp and beat everything I’ve tried over the years (and that is a lot of tubes!)

I have some RCAs from the early 60's that are super quiet and sound fantastic....
They are labeled , etched 12ax7wa which I believe is a mil spec designation