PURPOSE: To provide a light weight, highly rigid mixer chassis device with a simple arrangement by mounting a module of acoustic mixer to a frame made of a hollow metal rod and covering the module with a case.

CONSTITUTION: A frame 11 comprises pieces of a hollow drawn aluminum material 11a. The section of these pieces is rectangular and they are assembled into quadrangle with the rear end 11b of the frame being stepped, and the respective joints thereof are welded together. One end 12a of a module unit 12 of acoustic mixer is fixed to the rear end portion 11b by a screw 13 and the other end 12b is fixed to the front end portion 11c by a screw 14. On the bottom side of the frame 11 a bottom case 15 for covering the bottom side of the module unit 12 is inserted into the frame 11 interior and fixed by a screw 16 from within the frame 11. Then a meter case 17 is mounted along the side portion 11b of the rear end of the frame 11. Accordingly, the frame 11 is fabricated by the hollow metal rod which is excellent in rigidity with additional members attached to the hollow metal rod, thereby making the frame light in weight and simple in construction and increasing the rigidity.