An adjustable mass eccentric for a multi-amplitude vibratory mechanism can comprise a body and an internal cavity defined by the body such that the body surrounds the internal cavity. The internal cavity can include a first section, a second section, and a third section between the first section and the second section. The third section can define a volume and/or an area less than respective volumes and/or areas of the first section and the second section of the internal cavity. Filler material may be provided in the internal cavity and can migrate to and from the first, second, and third sections based on rotational movement of the body and internal cavity.