ABSTRACT
The basic idea of tape recording is simple enough: the audio signal flows in a coil forming part of what is essentially a small electromagnet. Then, at the replay stage, the tape passes an electromagnet similar to the one used for recording and the variations in the magnetic field round the tape induce a small electromotive force in the coil of the head. Fortunately analogue tape machines are very stable and the bias usually needs to be set only occasionally, although where these machines are used in mobile work they should be checked regularly, as vibration when being moved may disturb the control settings. There are broadly two methods of editing analogue tape: dub editing and cut and splice editing. An azimuth error, then, causes a reduction of the audio high frequencies - an unintended top cut. Correction of the azimuth is a rather skilled business.
