A signal processing system and method is disclosed for applying time-based effects to an N-channel audio input signal for reproduction on a set of loudspeakers having a predetermined configuration. A first M-channel audio signal is produced from the N-channel audio input signal. Each channel of the first M-channel audio signal is associated with a subset of the loudspeakers. A second M-channel audio signal is produced from the first M-channel audio signal according to an M×M matrix, each element aij in the M×M matrix including a delay term. A minimum value of the delay term in each element aij is determined according to a distance between at least two loudspeakers in at least one of the i and j subsets of loudspeakers and according to minimum delay value of a time-based delay effect applied to each channel of the second M-channel audio signal. A K-channel audio signal is then produced from the or each second M-channel audio signal.