Control of self-excited third octave vibration in a metal rolling mill can be achieved by adjusting the tension of the metal strip as it enters a stand. Self-excited third octave vibration can be detected and/or measured by one or more sensors. A high-speed tension adjustor can rapidly adjust the entry tension of the metal strip (e.g., as the metal strip enters a mill stand) to compensate for the detected self-excited third octave vibration. High-speed tension adjustors can include any combination of hydraulic or piezoelectric actuators coupled to the center roll of a bridle roll to rapidly raise or lower the roll and thus induce rapid tension adjustments in the strip. Other high-speed tension adjustors can be used.