An audio system includes a passive radiator that is attached to one end of a lever arm. The other end of the lever arm is attached to a mass that serves to move out of phase of the passive radiator to cancel mechanical vibrations of the passive radiator, but without significantly affecting audio output. The lever arm is attached to a mechanical ground, which may be the enclosure on which the passive radiator is mounted. A system may use multiple lever arms to reduce rocking of the passive radiator.