The present invention is directed to a diaphragm for loudspeakers which is integrally constructed through the combination of a core material being formed as a disc-shaped solid construction through the independent or series of combination of a plurality of flat-plate pieces and disc-shaped skin materials each being approximately equal in diameter on the top face and the bottom face of disc-shaped core material, the core material and skin materials being made of either boron or beryllium, thus resulting in the higher efficiency, wider zone and lower distortion of the loudspeakers.