A method for placing a predetermined number of notch filters in a disc
drive servo control system to attenuate noise frequencies, in order of
decreasing resonance magnitudes, is disclosed. The method involves
calculating an open loop response for a response spectrum of the drive,
calculating a notch filter for any noise frequency that exceeds a
threshold, mathematically applying the notch filter into the servo
control system, recalculating the open loop response and applying another
filter for a noise frequency that exceeds the threshold and repeating
until no noise frequencies exceed the gain threshold; selecting another
frequency range and repeating the same process until a predetermined
number of notch filters has been placed in the servo control system.