Looks like you are farther along than I am with the old Radiola which I bought. Here is a bunch of stuff on the 01A including the data sheet: http://vinylsavor.blogspot.com/2013/10/ ... x201a.html
You seem not satisfied with the sound with your horn speaker. I'm not sure what can be expected, but you should be able to connect it to modern electronics to get some idea. Just keep the output low as I believe these speakers are much more sensitive than modern moving coil speakers. I have never seen inside one of those speakers but I'm guessing that they have a metal diaphragm like an earphone of the period loaded into the horn.
I found a balanced armature paper cone speaker for the Radiola. I had never seen inside or heard one of those before. I hooked it to a small amp and while it would not rival a moving coil speaker it was better than I would have expected.
Big B5515 wrote: ↑14 Oct 2019 08:24I finally got around to trying out the Freed Eisemann tonight, after picking up a 6V, 5AH SLA battery for it's heater power. I had bought the 9V batteries over a year ago, which were a little weak from the start, but after 3 hours, the heater battery was about discharged, and the 10- 9V batteries in series were still at 81V. It was a bit tricky trying to find a station, I finally used the signal generator to figure out dial settings for 650 and 740, both of which I was then able to tune in. Unless listening to a weak signal, the extra gain of the last tube only made sound more distorted, the medium level output usually sounded clearer and reduces current draw, as last tube's filament only has power when speaker is plugged into loud connector. The volume level was not exactly loud either way, and sound quality is nothing to write home about. As the last tube was more sensitive to heater voltage, I suspect it may be weak, however it seems I heard 01As are only good for maybe 100mw, or so as a AF amp. I've yet to check the tubes, or do anything to it yet, but noticed that I do need to try to tighten up the center dial's variable capacitor which now turns a little too easily.