Looking for technical info all about speaker technologies from the 20’s through the 50’s. Looking for that “rare” detail about dynamic vs non-dynamic, power handling, load, inductance, etc? Can anyone point me references that can give me these? Almost none of the technical schematics of these eras provide this, nor do the various parts catalogs. These just show a “speaker” and of it is a electrodynamic or not. And what the specifications are for these? Did Jensen ever put together a catalog that would help take any mystery out of what the best speakers are for various radio brands? Did Scott ever provide specs for the speakers they sold or recommended for their radios? If so, where would that be found?  Thanks.