whilst it would be impossible to list here all of the eddy-currents and fields that will be generated within the proposed rig, two of the more obvious are:

any vibration in the string will produce voltages in the piezo transducers; this primary voltage will apply to the main coils, wound from the spare string stock.

current will also flow in all of the constituent parts of the speaking length: the carbon core, the wire winding and the water strings (all diamagnetic); each will produce its own individual eddy-currents and fields (extremely complex).