1. An adaptive control system having a system input and a system output, the adaptive control system comprising: an adaptive control filter having a bank of non-adaptive pre-filters that receives a reference signal, each non-adaptive pre-filter in the bank outputting a pre-filtered reference signal, a linear combiner that receives the pre-filtered reference signals and outputs output signals, the linear combiner having adaptive weights and fixed weights, and a summer that receives the output signals from the linear combiner and outputs a constrained correction signal that is used to control the system output; and an error sensor that senses the system output and generates an error signal that is used to adapt the adaptive weights in the linear combiner.