Abstract: An extruded recording sensor mounting rail for keyboard operated musical instruments, particularly electronic player pianos, which can be used to install recording sensors in a new or existing piano. First and second flanges extend longitudinally along the front and rear of the mounting rail. A shelf is provided on the first flange, with the shelf configured for receiving and supporting one edge of a circuit board in a sensor assembly. The first flange includes a groove adapted to receive a threaded fastener for securing the edge of the circuit board onto the shelf. In the preferred embodiment, the second flange includes an inward facing lip which defines a flute configured for receiving and supporting the other edge of the circuit board. In the alternate embodiment, the second flange includes a shelf and a groove adapted to receive a threaded fastener for securing the other edge of the circuit board onto the shelf.