Television audio signal encoders include a matrix that sums a left channel audio signal and a right channel audio signal to produce a sum signal. The matrix also subtracts one of the left and right audio signals from the other to produce a difference signal. The encoders also include a configurable infinite impulse response digital filter that selectively uses one or more sets of filter coefficients to filter the difference signal and/or the sum signals. Each selectable set of filter coefficients is associated with a unique filtering application to prepare the difference signal for transmission. Decoders with the matrix are also disclosed.