Gainy, low microphonic, well built, but a bit noisy.
These look like they should be pretty kick a**. They are a gainy little 12AX7. They remind me of the Sylvania STR 12AX7, only the Sylvania is graveyard quiet. These were hissy little tubes. I got a whole boatload cheap. I thought maybe I got bad ones, but others are about the same. The noise is not guitar amp objectionable, until you are in the studio. Rating like with like, and not with NOS these are an oaky value. I have had noisy RCAs too, but not consistently. These just have some hiss. Nothing major like hum, or dirty pot scritchy scratchy noises. They have the usual kinda shortened life we come to expect for the price paid. GAINY LITTLE SUCKAS! These test hot too!