Analysis of magnetic modulators, which includes low-level transducer amplifiers and magnetometers, usually is based on control-signal displacement of fixed hysteresis loops of some particular shape. Experience shows, however, that many qualitative aspects of the device operation do not agree with the analysis. In this paper, an analysis is based on the

widening of the hysteresis loop, which is applicable to metal alloy tape cores. The analysis makes possible the comparison of amplifiers using different magnetic materials by relating small-signal gain and output waveform to measurable properties of the material.