The knowledge of the recorded signal amplitude on a magnetic record (which may be in the form of a tape, a disc, oτ a perforated film) has several practical uses: (1) for determining and standardizing references for the levels of audio programs on these magnetic records; (2) for specifying the recording-performance properties of magnetic media (for example, the distortion versus flux, etc); and (3) for measuring and specifying the sensitivity of reproducing heads (and also, by reciprocity, recording heads). The quantity for specifying the recorded signal is the short-circuit magnetic flux, sometimes simply shortened to flux. Several possible methods exist for measuring tape flux, but the measurement given here involves only the use of a calibrated ring-core head which is described in the reference of the standard. Note that the present standard measurement is only for "medium wavelengths". A further standard method for measuring short-circuit flux at long wavelengths and at short wavel...

This standard specifies a method of measuring the recorded flux per unit width of a magnetically recorded test signal at medium wavelengths for all magnetic sound record formats. It also specifies the equipment needed to implement this method.