A robust alternative of the delayed resonator is proposed by spectral approach. By double root assignment at the excitation frequency, which is projected to widening the stop-band in the active absorber frequency response, the performance sensitivity to the mismatch between the design and true excitation frequency is considerably decreased. Additionally, the overall scheme is supplemented by a control loop which improves the stability margin. The design is validated by simulations and the results are compared with classical delayed resonator.