The invention relates to a system for detecting defects, said system comprising a plurality of magnetic field sensors that can each generate a field value representative of the magnetic field measured; a module for balancing field values generated according to a pre-established regulation in order to equalise the field values generated in the absence of defects, the pre-established regulation depending on the field values generated in the absence of defects by each of the sensors; and a field generator which is controlled by the balancing module in order to modify the field measured by each of the sensors according to the pre-established regulation.