[en] Magnetic pick-up transducers for high-Q gravitational wave antennas are studied. The sensitivities of two recently proposed devices are evaluated from a general point of view. A general treatment of these systems as two coupled oscillators is used. The noise properties of these devices, taking into account the reaction of the electronics back on the antennas and the measuring times, are determined. A modification of the systems to operate as mechanical impedance transformers is also discussed. A comparison of two recently proposed magnetic transducer schemes with a mechanical impedance transformer scheme is made