Abstract: An optical pickup transducer senses vibrations of string instruments transducing the vibrations into an electrical signal with fidelity, high signal-to-noise ratio and with exclusion of extraneous effects such as noise. The transducer includes a housing with an upper deck that holds one or more light emitters, and a lower deck that holds light sensors in a one-to-one arrangement with the emitters so that each sensor is physically in opposition to each emitter. For application to the string instruments, each string is conducted through the light beam between an emitter and a sensor. The sensors may be photodiodes, so that their electrical output is related to the amount of incident light and therefore varies with the movement of the string, that is, the string modulates the incident light on the photodiode. This electrical output is then amplified to drive a loudspeaker.