///
        /// \note Assumes sample rate of 44100
        ///
        public LowpassFilter()
        {
            _leftFilter = new FirstOrderLowpassFilter();
             _rightFilter = new FirstOrderLowpassFilter();

             // Use set function to initialize private members:
             cutoff = 150.0;        // hz
        }
        ///
        /// \note Assumes sample rate of 44100
        ///
        public HighpassFilter()
        {
            _leftFilter = new MonoHighpassFilter();
             _rightFilter = new MonoHighpassFilter();

             // Use public "set" function to initialize everything:
             cutoff = 150.0;        // hz
        }