1. Connecting the negative pole of the multi-meter, and find
out the test point of each tube.
2. Using a small screw-driver to slowly adjust the adjust
switcher, till the test voltage reach the 0.40 ~ 0.43V
Repeating the steps above for each power tube. Please keep in
mind for that the bias voltage of each tube is best at same level.
Congratulation! You just updated your Jasmine Piano
EL34-PP Tube Amplifier!
Step Three: Adjusting Bias-Voltage of the Tubes