Tape Response

Author: N.H. Crowhurst

With magnetic recording, the output from the tape passing the gap is proportional to the rate at which the magnetism changes. Consequently, it will rise with frequency, at least up to a point where the length of the effective magnet on the tape is about the same as the air gap on the head that is used to pick up the magnetization. When the frequency gets higher than this, the air gap will start to compare the magnetization on the tape at half a wavelength or more, and cancellation begins to occur.

Tape Response

This means we get a rising response all the way up to a certain frequency (which is dependent on the width of the air gap and the speed of tape travel), which falls off very suddenly to zero. Equalization of the input signal, the output, or both, compensates for the characteristic. The magnetization on the tape theoretically is proportional to the current applied to the recording head. This does not allow for losses in the head, however, which complicate the response somewhat, Because of these complexities, only playback response is specified.