Background
German engineer Eduard Schüller created and patented the Magnetophon, a high-fidelity audio recording and playback machine. Working for German company AEG, he patented the invention in December 1933. AEG was a leading electrical company that had evolved from the Deutsche Edison Gesellschaft, the German Edison Company.
Schüller perfected an earlier tape-recording device invented by Oberlin Smith, an American engineer, though Smith’s device never functioned well. Schüller used magnetic tape, invented and manufactured by Fritz Pfleumer and eventually owned by BASF, to record sound.
By the time of Shüller’s invention, AEG was a Nazi supporter. The AEG recording technology was unknown outside Nazi Germany.
Due to the high playback fidelity, recordings sounded live. Hitler routinely recorded himself and the recordings were portrayed as live speeches in one city, to make it sound like he was there, when was actually somewhere else. After the war, allies found 350 Hitler recordings.
Magnetophon worked well for speeches but not for music until Pfleumer, from German company BASF, invented a better type of recording tape.
Ampex
After the war, US engineer Jack Mullin brought Schüller’s device, called a Magnetophon K (K stands for Koffer, or suitcase; portable), to the US. There it came to the attention of engineers at AMPEX, a US electrical engineering business then focused on small motor design.
AMPEX realized their expertise in small precision motors overlapped with the need to mass-produce the recording devices and built a highly successful audio recording business. AMPEX recorders marked the beginning of recorded radio broadcasts; before the Magnetophon commercial radio broadcasts were live. Decades later, AMPEX would innovate the video recorder and do the same for television broadcasts.