#### Lancer X

##### TDPRI Member

*(No finished pics until the custom logos etc. arrive...)*

So, I ended up at 5.7W plate dissipation, which is 103.6% of ideal for this 12AU7 power tube. Not one to do things half way, I want to tweak my cathode resistor to bring her down to ~100%. (This is a cathode biased amp.)

I have been Googling how to calculate

* Plate-to-Cathode 338 V

* Voltage across Cathode Resistor 13.8 V

* Cathode Resistor (actual measured) 810 ohms

Plugging these values into @robrob's "Tube Dissipation Using Cathode Resistor Voltage Drop" calculator, the following values emerged:

* Plate Current 17 mA

* Plate Dissipation 5.7 W

* % of Max Dissipation 103.6%

So, given these values, is there an accurate way to calculate what value of cathode resistor would get me down to ~5.5W of plate dissipation?

I did try to Google for the answer of this question, but didn't gather any useful info. I'm guessing this isn't a simple V=IR situation - seems like the situation is much more interdependent than that??

Thanks in advance!