1. A chest valve for pipe organs comprising an air chest for holding a supply of air under pressure, at least one aperture in the top of said chest leading to an organ pipe, a second aperture in the bottom of said chest disposed in alignment with said one aperture, sleeve means disposed in said one aperture and extending through said chest and said second aperture to define an annular valve seat on the end extending through said second aperture, an auxiliary pipe control unit for each pipe secured beneath said second aperture outside said chest comprising auxiliary chamber means, a taut thin flexible resilient diaphragm forming one wall of said chamber and normally disposed in sealing relation across said valve seat when the air pressure in said chest and said chamber are equal, a valve body secured directly to said chamber means outside said chest, first passage means connecting the interioR of said chest to the interior of said chamber, second passage means connecting the interior of said chamber to atmosphere, valve means in said valve body disposed between said chamber and said first and second passage means, said valve means normally disposed to maintain said chamber in communication with said chest through said first passage means while closing said second passage means, and operator controlled means for shifting said valve means to open communication between said chamber and atmosphere through said second passage and to close said first passage whereby the pressure differential acting on said diaphragm will shift said diaphragm away from said valve seat to allow air under pressure to enter said pipe through said sleeve.