A new passive/active dynamic vibration absorber is proposed for structural vibration control. The device consists of two reaction-masses attached to the primary structure through elastic elements. The active force pair is applied between these two reaction masses. This configuration should be contrasted to the traditional single reaction-mass system where the control force pair is implemented between the reaction-mass and the primary structure. The performance of the new device is evaluated by controlling the response of a cantilever beam subjected to white noise excitation. The control approach used is the feedforward algorithm. For purposes of comparison, the results are compared to the performance of an equivalent single reaction mass device. The results show that the proposed dual-mass dynamic vibration absorber actuator achieves the same level of vibration reduction using only half the control effort required by the single reaction-mass actuator. In addition, the concept of force transmissibility function is introduced. This function is the force applied by the hybrid dynamic vibration absorber onto an infinity impedance due to a unit control force. It is demonstrated that this function is an effective means to determine the potential of these devices.