acoustic vs. electronic

I think that the ones before 1925 could have been recorded on an Edison wax cylinder, cutting them by using a stylus driven only by mechano-acoustic power amplified by focusing sound waves using those big metal horns. After 1925, electronic amplification was available. Call this an educated guess...I may be wrong

probably right based on the sound quality, thanks

Yeah, it should have a lot of static and noise, and have
no bottom or top end, with very limited dynamic range.

It was long believed that those early (pre-electronic) recordings had "a lot of static and noise, and no bottom or top end, with very limited dynamic range". In recent years it has been discovered, through digital conversion and analysis, that high and low frequencies are actually present, though greatly attenuated, and the noise can be modeled and removed. I have heard restored recordings that are nearly a hundred years old which sound like they were made in the 1950's.