You are undertaking a great project but it is going to be a big task and will take a lot of time. I fear that the scope is probably beyond what you can accomplish in an introductory spice course. Here is an excellent reference where a similar analysis was performed on a Fender Bassman 5F6A
amplifier. I have to warn you that it is a difficult read unless you have experience in network analysis. On the other hand, you don't need to understand everything in order to gain something from it. On the same web site they present an analysis of a James tone circuit
which is very similar to the one found in the B-15. You might find it interesting to check out the Fender 5E3
power amp analysis.
Buying the transformer set that fliptops offers is a good idea. You will have the proper transformer set for the job. There are good tutorials out there on how to build an eyelet or turret board to build the circuit on. There is some good practical build information and schematics here
. The have been several revisions of this amplifier over the years, the B-15NC is a good schematic to adopt for your project. I think that it is the most classic version. The one I like the best anyway.
There aren't a lot of specs for the transforms available.
Here is what I can offer from some notes that I have:
PT-108 (used in the early cathode biased models):
PT spec: 750 VCT (375-0-375) secondary, 150mA, 5 VAC @ 3A with 117 VAC primary
DCR average of one half of PT secondary winding: 55.5 ohms (measured)
DCR PT primary winding: 2.5 ohms (measured)
PT secondary average high voltage to center tap voltage / PT primary voltage: 372 / 117 = 3.18 (measured)
NOTE: The 372 volts was measured with line voltage of 117 VAC.
Total impedance presented to rectifier by power transformer = 55.5 + (3.18 * 3.18) * 2.5 = 80.8 ohms per plate
At 372 volts, the 5AR4 tube requires limiting resistors of at least 27 ohms @ 5-10 W in series with each anode to bring the total resistance up to 112 ohms as per the Amperex 5AR4 data sheet. These are never used in these amps but might be of interest for modeling.
The OPT for the early model B-15 is the OT-208. I can't locate my OT-208 specs but I do have something for the OT-214 which has a slightly higher output power transformer and was used in the later fixed bias models of the B-15. Very similar though and this is the OPT that Fliptops sells for all B-15 amps.
Primary: 6.5K, DCR 290R
Secondary: 8 and 16 ohms, DCR 1, 1.4R
Hope that this helps.