Electrodynamic pick-up for electric string instruments

The most important elements in electric musical string instruments are pick-ups. They convert vibration of strings into electric signal. Usually, two types of pick-ups are used: electromagnetic and piezoelectric. Electromagnetic pick-up, called also a pick-up with moving armature, converts vibration of string into an electric signal using change of magnetic flux in the magnetic circuit by the vibration of the string made of magnetic material. Vibrating string causes change of the air gap between the string (which is a moving armature) and rest of magnetic circuit. A variable electromotive force is generated in the stationary winding. In order for it to be proportional to the speed of vibration, polarization is needed, which is achieved by using a permanent magnet in the magnetic circuit. In a piezoelectric transducer, an electric current is generated due to the deformation of the piezoelectric material under the influence of a vibrating string. The subject of this paper is description of a stringed instrument with a electrodynamic transducer, which converts mechanical vibration of strings into an electromotive force which is produced between the ends of moving wire placed in the permanent magnetic field. This transducer is also called a transducer with moving wire. A wire (string) is made of a conductive material, but not necessarily a magnetic material. The principle of operation is similar to that of a ribbon microphone. The electromotive force induced at the ends of the string is very small and must be strongly amplified. It’s a novel technique which is applicable in electric stringed instruments such as guitar, violin, viola, cello, double bass, and others.