Pfleumer, Fritz, Dresden 1928
Lender: Deutsches Technikmuseum Berlin
Magnetophon AEG K4
AEG, Berlin 1938
Model: AEG K4
48 x 48 x 34 cm, ca. 40 kg
Wood (foil laminated), magnetophon tape, three magnetic heads, three motors with special deceleration and stopping systems, tube amplifier

A recorder-converter (recording head) converts audio-frequency electrical signals into magnetic fields that cause a permanent magnetization of the magnetophon tape as it passes the head at a constant speed. When played back, these magnetic fields induce voltages in the playback converter (playback head) and are made audible by means of amplification in a loudspeaker. The constant mechanical tension of the tape is achieved by a “sound motor” for transporting the tape at constant speed during recording and playback, and two fast-wind motors for fast-forward and rewind. The 6.5 mm wide and 1,000 m long tape can, at a speed of 76 cm per sec., record around 21 minutes of sound.