The invention provides an active noise reducing filter apparatus for actively reducing noise d from at least one primary noise source reference signal x. The apparatus comprises a secondary source signal connector connected to a secondary source generating secondary noise y based on a secondary signal u for reducing said primary noise d. A sensor connector is connected to a sensor for measuring said primary and secondary noise as an error signal e. A reference signal connector receives the reference signal x, and a control filter W receives the reference signal x and calculates a control signal for providing the signal u. An adaptation circuit receives said error signal e and reference signal x and adapts the control filter W. The adaptation circuit adapts the filter W using a representation of said secondary source including a secondary source transfer function G of said secondary source and an additional damping for providing improved stability.