Wanting to do some DIY and remember my old Dyna ST-70 that had octal sockets on the front of the chassis. To set the bias you would fire it up, set it at 1.56 volts if I remember, and after it was good and warmed up, check it again and correct. There was a pot with a shaft made for using a flat headed screwdriver on to change the bias setting.
What I want to do it to mount some meters so I know what the bias is all the time. I plan on using 6V 2A3 types and would like to know the bias setting so I can look for the correct type of meters and pots.
The first thing is if your going to use 6A3's the B+ is way too high , it should be around 300 volts and the ST 70 more like 480 to 500 volts . If you use Russian 6B4G's it could get away with 400 volts . The bias volage sould be around -61 volts for 80 MA iddle current or 470 ohm for a shared cathode resistor . The output transformers are 4.2K ct in the ST70 so you will get about 8 to 10 watts output with fixed bias and 5 to 8 watts with a cathode resistor