Precision AC voltage, current, phase, power and energy measurements and calibrations with current ranges from 1 uA to 20 kA and voltage ranges from 1V to 1000 kV are now performed with accuracies of better than one part per million. Continued demand for improved accuracy has led the inventors to address improvements to dual stage and multi-stage current transducers that may form the basis of the measuring process within many of the measurement instruments providing the precision AC measurements and calibrations. Additionally, the improvements to dual stage and multi-stage current transducers provide for novel feedback controlled precision AC current sources without requiring measurement of the AC current source output directly.