Abstract: Apparatus and methods to reduce unwanted motion in a payload of a precision instrument are described. The payload may be supported by an intermediate mass. A feedback signal based upon sensed motion of the intermediate mass may be applied to an intermediate-mass actuator arranged to drive the intermediate mass. Additionally, a feedforward signal may be applied to a payload actuator arranged to drive the payload and used to suppress unwanted motion of the payload. The feedforward signal may be derived from a source within the apparatus or external to the apparatus that would otherwise cause unwanted motion of the payload.