Disclosed is an improved loudspeaker comprising a pre-stressed cabinet and a loudspeaker unit fixed to the inside of the cabinet. The cabinet comprises a hollow conical assembly including two conical bodies of high-rigidity metal, one press-fitted into the other by applying an increased compressive force. The hollow conical assembly has front and rear plates closing its front and rear openings. These front and rear plates are pulled toward each other by tightening screw rods.