A back frame for a piano or like instrument is comprised by a laminated composite structure having outer laminates of sheet steel and an intermediate laminate which is formed by a reconstituted wood product. The steel laminates are joined to the intermediate laminate and the intermediate laminate is substantially thicker than the sheet steel to offset the outer laminates from one another and increase the stiffness of the structure. A plurality of integral beam elements extend through the laminated structure in the same general direction as the tensioning load of the strings in the piano, and the elements are spaced from one another and define openings in the frame through which sound is emitted from the sounding board of the instrument.