> nothing wrong with the 12AX7. It is one of the very few tubes actually designed for audio use
More likely a fire-control op-amp part. Who the heck would need that much gain TWICE in an audio path? And in 1947, not a high-point in audio history.
Surely derived from 6F5/6SF5, slightly improved and doubled-up.
Yes, soon after registration it became a go-to for many audio designers, and the makers began to care a little about audio faults, though often pushing different types (12AX7A, 6EU7, 7025) to be sure of getting the audio mods (and prices).
It is about the best Gm/Ik of any common tube.
More likely a fire-control op-amp part. Who the heck would need that much gain TWICE in an audio path? And in 1947, not a high-point in audio history.
Surely derived from 6F5/6SF5, slightly improved and doubled-up.
Yes, soon after registration it became a go-to for many audio designers, and the makers began to care a little about audio faults, though often pushing different types (12AX7A, 6EU7, 7025) to be sure of getting the audio mods (and prices).
It is about the best Gm/Ik of any common tube.
