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RE: Cathode bypass cap removed and I like it

Posted by Tre' on January 11, 2017 at 12:12:40:
The amount of negative bias is dependent on how much plate to cathode voltage you will have and how much current you want flowing through the tube at idle.
The schematic left out the grid resistor. The grid resistor would go between the grid and the top of the battery.
If you change from cathode bias to fixed bias on your 2a3 there will be more plate to cathode voltage because the cathode will be at zero volts where as now it's at +45 volts or so.
That will change the amount of negative voltage you will need to reach the idle current that you want.
If you use a negative supply (instead of batteries) that delivers more negative voltage than you need then you can make it adjustable and you can set it where you need it.
I hope that made sense.
Tre'