US Patent 7928303 Insert for cajon drum

An apparatus is provided for lowering the fundamental frequency of a cajon drum. A first side wall of the cajon drum is the drumhead. An opening is formed in a second side wall, wherein the opening may be circular, oval, rectangular or other shape. An insert having a cross-section conforming to the shape of the opening is slid into the opening and mounted to the side wall in which the opening is formed. Various techniques for connecting the insert to the side wall of the drum are disclosed. The insert may be fitted into the drum opening during the initial manufacture of the drum.