The layer wound dielectric material is Glasiene paper, rice paper with beeswax infused. Likely about 0.001 to 0.0015 inches thick. Used so that it would not be impregnated with the varnish, just coated. This will make a big difference in eventual sound quality, as all tone is E Field losses or storage.
By the way is the D you reference a dissipation number for the capacitance?
we can do this, two coils involved but they are both identical,
so we can use DCR from one of the coils,
33 lams x .014" lam thickness = 0.462" stack,
a 31 UI lam has legs that are 5/16" wide,
so the core tube is .3125" x 0.462" and about 0.1" thick,
MLT calculator gives 2.25" x 2900 turns = 6525"
6525/12=544 feet of wire,
DCR is 734 ohms per coil (pri)
1000ft/544ft = 1.838 so if this wire were 1000 ft long it would ohm out to
1.838 x 734 = 1349 ohms per 1000 ft,
our wire chart says that #41 has a DCR of 1323 ohms so you have made a very good guess as to the pri wire size!
My first guess was 40AWG, it being a round number but when I worked out the average length per turn the total DCR would been about 1Kohms so too little for the primary winding. Good stuff then, 41AWG for the A-24.
I couldn't find it anywhere so I think this thread in the most appropriate...
What are the differences in different UTC versions of this transformer? There are black, dark grey and light grey versions. The black is supposed to be the oldest version... what about the other two? Any obvious sonic differences?