I use RAM 6922's in my ARC phono amp and they are by far the best tubes I have ever used.
Mitchum or Blackburn for the Mullard 6922?
Do Mitchum production and Blackburn production sound different in the Mullard 6922? I believe I once read somewhere that Mitchum made tubes for the military, whereas Blackbutn did not, so, presumably, with better materials and/or tighter tolerances or testing.