Once a month should be fine as long as your tubes seem to be stable. I would not suggest biasing it every time you turn it on. My Spirit II is not auto bias, but it is quite stable with a good set of Black Treasure KT88's. It is not that critical that each tube be within a few points of each other. You will not be able to hear a difference if they are off by just 10 points or so. Have you tried rolling different 12AU7's in it yet? The amp sounds even better with some nice NOS Amperex Hollands or Mullards. The Amperex 7316 is a real eye-opener in these amps too. Enjoy!
2 responses Add your response