meas boogie 400-rebias for new tubes?

Discussion in 'Amps and Cabs [BG]' started by rogerbodyshop, Jan 14, 2009.

  1. rogerbodyshop

    rogerbodyshop Guest

    Jan 14, 2009
    I just acquired a Mesa Boogie 400 head from the original owner and he installed 6 new Mesa tubes but didn't have the bias that needed on these amps?
  2. not if you use the right mesa tubes - or other tubes rated for the fixed bias of your 400.

  3. mikeswals

    mikeswals Supporting Member

    Nov 18, 2002
    Seattle / Tacoma
    There is no adjustable bias pots on these. You do not need to even if you are using brand X tubes. Just be sure to use a matched set. When I bought my Bass 400 back in '91 and immediately popped tube, I lived way out in the sticks and it was a 3hr drive to visit the big city where anyone sold amp tubes. When I visited the Mesa boys they told me just buy matched sets of whatever brand I want.
    You can have a tech install a bias pot so you can get max life out of a tube set, but so far I really haven't seen the need.