An apparatus for producing fiber material or the like with a prescribable feed weight comprises a conveyor for delivering the fiber flock to a filling stack, which includes a vibrating wall extending in a vertical direction and a displaceable wall, a stationary delivery roller being arranged in a discharge region of the filling stack and a displaceable delivery roller being arranged opposite the stationary roller in the discharge region for controlling the thickness of the layer being deposited on a conveyor. The apparatus also includes a pressure sensor which is provided between the two delivery rollers, which pressure sensor provides signals for controlling the displacement of the displaceable delivery roller, the vibratory frequency for the vibrating wall of the stack and the displacement of the movable wall.