Sometime ago I purchased a used Egnater Rebel 20 head from our DC/MD/VA used gear emporium, Atomic Music. Included were a nice carrying case/bag with paperwork/user's manual stuff. As many know, this amp has 2 sets of tubes: 6v6 and EL84s. Nowhere in the paperwork does it say whether or not these tubes are fixed or cathode biased. About 2 weeks ago, I sent an email to Egnater with the question, but have not received an answer. I want to put in a fresh set. Does anyone know?