Hello, I have an Eico HF-81 that uses a common 165 ohm cathode resistor bypassed with a 50uF cap in each output stage. The plate voltage is 335v and cathode 12v, it uses no ultralinear. I read that using seperate cathode resistors limits out of balance voltage in the primary of the output transformer. What would be the resistor values for each tube? What are the pros and cons of this method verses using a common resistor?

: Hello, I have an Eico HF-81 that uses a common 165 ohm cathode resistor bypassed with a 50uF cap in each output stage. The plate voltage is 335v and cathode 12v, it uses no ultralinear. I read that using seperate cathode resistors limits out of balance voltage in the primary of the output transformer. What would be the resistor values for each tube? What are the pros and cons of this method verses using a common resistor?

Hello, two separate cathode resistors of 330 ohms would
do the trick. Remember, you will need two separate cathode-bypass
capacitors also. I dont see any advantage in two separate cathode
resistors. A single resistor circuit (stock) would tend
to keep the two tubes in balance, exactly what you want
it to do.

: Hello, I have an Eico HF-81 that uses a common 165 ohm cathode resistor bypassed with a 50uF cap in each output stage. The plate voltage is 335v and cathode 12v, it uses no ultralinear. I read that using seperate cathode resistors limits out of balance voltage in the primary of the output transformer. What would be the resistor values for each tube? What are the pros and cons of this method verses using a common resistor?
A better modificaiton to your circuit would be to use
a 12 volt, 5 watt zener diode in place of the resistor.
This yields a stable bias and eliminates the need for
bypassing with capacitors altogether, in fact, you can
take them out of the circuit completely. The power amps will then have
much better low frequency response than ever.