Current tap in PSUD2 (Duncan Amp Pages power supply calculator)

[jackplug1]

How do you calculate the value of the current tap, for example in a typical fender champ output stage of 320v B+ 5000k OPT primary, 500 ohms cathode bias resistor
25uf bypass capacitor (20vdc)

https://www.duncanamps.com/psud2/index.html

[shooter]

start with your "target" data;
320vdc 5000 ohms
I= e/r = 320/5000 = 64mA
if the 5000 ohms is "shared with 2 tube, then I gets divided in 1/2, giving you 32mA a tube
from there it's all down hill 

[PRR]

Those "current taps" cause more trouble than they are worth. Use resistor loads! Yes, you can only have one, but in a 3-stage amplifier you can figure the small stuff on a napkin.

A "good" load for SE pentode is similar to V/I how you run the 6V6. Shooter suggests 320V and 64mA. Note that 20 Watts is awful hot for a 12-14W tube. Champs are often run nearer 40mA and many use 7K load. In any case, pretend the Full Roar loading is like a resistor of 5k or 7K.

In college, you need to put the 500 Ohm Rk somewhere. In your private lair, with 6F6 or other low-Mu tube, you might roll it into the load resistance. With 6V6 EL84 etc in loudspeaker duty, forget it, not worth bothering.

[shooter]

As PRR pointed out 60mA is real hot for 6V6, the tube datasheet will confirm that.


so either the math was wrong or the assumptions are, once that's solved decide which variable you're gonna change to make the datasheets happy, confirm with math. 
by getting creative you can double your speaker impedance, making the OT primary, in this case, 10k
320/10,000 = 32mA, your "target" value
eventually you'll be close enough to plug in the iron
or not 

[jackplug1]

My post was to ascertain if the current tap is easily calculated by ohms law, which seems to be the case.
I have to confess that some of of the figures I posted were erroneous and did not relate to exactly to what I have here, which is:
313vdc B+ and an unknown transformer which i believed to be 5K to 3ohm or 15ohm
A did a simple test to calculate the winding ratio, volts applied to the secondary is 6.37vac out 228.8vac (36 ratio) and using the 6v6 data sheet 315vdc and load resistance of 8.5k revealed that the speaker impedance would need to be 6.7 ohm - within range if an 8 ohm speaker reflected 10k, which would be 31.3ma.
I hope that is correct ?