Systems and methods for providing a drop seal assembly which is concealed within an opening in the bottom of a sliding door panel of a top-hanging sliding door. The drop seal assembly may include bottom guide which defines a downward facing elongated slot or track which receives a sill guide therein. The drop seal assembly also includes a drop down acoustic seal which automatically drops down to contact the floor surface below the door panel when the door panel is moved from an open position into a closed position. The distance that the seal drops down upon closing of the door panel may be selectively adjustable to accommodate variances in the air gap between the door bottom and the floor surface due to particular installation conditions. A concealed magnetic bottom seal activator may be used to provide self-adjusting activation of the door bottom seal assembly using two opposing magnets.