Bias calculator Select your tube type and amp class (Class A, Class AB, or high AB) and enter your Plate Voltage or B+. The calculator will give you the bias current for each tube. Use this as a guide for setting your bias. Tube type:         ----Choose---- 6L6/5881 6V6 EL34 EL84/6BQ5 KT66 KT88/6550    Amp class:        ----Choose---- Class AB (56%) High AB (75%) Class A (95%)    Plate voltage:    V Bias current for one tube:  mA