The Dreamtone calculator trims some of that fat off right from the git'go.
Measure the voltage drop across a preamp tube's cathode resistor and calculate the current the next time you have one of your amps open up. You will likely see that the actual current is lower than what you originally estimated. Likewise, but to a lesser extent in my experience, power section screens and plates.
So....we are really dealing in design margins for which we all have our own personal approach to.
Yes! One half of your estimated current through each of the pre-rectifier resistors. That adjustment to your spreadsheet will likely get you to where you want to be. Double check the math in Xgamer's last post. That is exactly what I would have predicted using your estimated HV current draw.
As you already know, the exact drop across those resistors will be affected by your estimated total HV current. So...again...your selected HV current margin will play into where you actually end up.
I would run your analysis on a couple of HV draw estimates across a range of values (Dream output the lowest, your estimate in the middle and an additional 10-15'ish% above that) to get a feel for the "zip code" that you will be working in. Then...procure a range of pre recto resistors that cover that zip code so you can tweak it later using actual measurements.
Sure...you could just close your eyes and pick a PT that feels right and there will be a 99.9% that it will work "correctly". But...that would take all of the "fun" out of it!!
Cheers,
Dave O.
