Spring assembly as part of a vibrator for a bone anchored hearing aid, wherein the spring assembly comprises a suspension spring having a first end immovably connected to a mass of the vibrator and a second end immovably connected to a coupling attachable to a user's skull bone and comprised by the vibrator, wherein the spring assembly comprises an adjusting means adapted to adjust a spring rate of the suspension spring between a first spring rate and a second spring rate, the first rate being higher than the second rate, so as to move a resonance peak of the vibrator.