The three heads have different jobs. Erase prepares the material by reducing its old recording. Record writes a new pattern into it. Playback reads that pattern after the tape has moved downstream. The connection between recording and playback is the material itself.
At the record head, the incoming audio passes through recording electronics and becomes a winding current. That current creates a magnetic field in the coating. A much faster alternating current, called bias, is added to help the material respond to the audio signal.
The coating retains a magnetic history after it leaves the head. In the animation, arrows show the lasting recording at eight depths. The outlined piece moves with the tape, and the close-up follows its recording through those depths. The drawing hides the rapid bias reversals so you can watch the retained pattern.
At playback, the moving pattern changes the magnetic flux linked through the head’s winding. A change in that flux produces voltage. Playback equalization then shapes the voltage into an output signal. The faint line in the output display is the earlier input, delayed by the travel between the heads, so you can compare their shapes.
This animation is a teaching model. It assumes effective erasure, uses independent magnetic histories and idealized head fields, and matches waveform levels for comparison. Its speed control changes the viewing pace. It plays no sound and is separate from the plugin’s audio engine.
tapefold is still being developed. The current plugin interface is a workbench with audio passthrough, while the physical recording engine is being developed separately. Check the available builds and their requirements for what a particular release supports.