A transducer for a stringed instrument comprises a first uppermost coil, and a second lowermost coil with the axes of the coils coincident. At least one permanent magnet pole piece associated with the coils and a shield of magnetically permeable material arranged between the coils with the...http://www.google.ca/patents/US5834999?utm_source=gb-gplus-sharePatent US5834999 - Transducer for a stringed musical instrument
