Bias Adjustment Sonaro

[george]

I have a 1967 Sonaro with EL34s and want to set the bias when I replace the output tubes. Do I need to add some 1K/1W flame proof resistors between the cathode and ground to measure bias current - or is there a simpler approach here?  I did a search but didn't find anything that answers my question.  THX

[loudthud]

You want 1 ohm, not 1K. You should go smaller than 1 watt if you want the resistor to act like a fuse. Kevin O'Connor suggests a 10 ohm 1W. What I do is remove the short wire between pins 1 and 8 and move any wires that go to pin 8 to pin 1. Then install the resistor between pins 1 and 8 so it's easy to connect a probe to the pin 8 side. Or, just use a bias probe.