Bias Calculator

Biasing your amp doesn’t have to be difficult. As long as you know (or can test) the plate voltage in your amp, and have a way to measure the idle current, you can determine where to bias it, using our calculator. Select your tube type and amp class (Class A, Class AB Low, Class AB, or Class AB High) 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:        
Amp class:       
Plate voltage:    VDC

Bias current for one tube:  mA


Note: This calculator is intended for quick reference only. Always refer to the manufacturer’s tube datasheet for absolute values. If you need more information on biasing your Granger amplifier, please contact us.

Need a bias probe? Order our bias probe from the Custom Shop.

Shop Hours


9:30am - 6:00pm CT

Weekends & Holidays




 (205) 774-0350


Granger Amplification LLC
132 Pinecrest Rd
Hueytown, AL 35023-1321