Abstract
To provide a sensorless bass compensation system including a double layer mixed control structure composed of a feedforward control device and a feedback control device and including a volume velocity estimation observer. <P>SOLUTION: The volume velocity estimation observer estimates a volume velocity according to a dynamical equation and a linear secondary Gauss law so that it does not need a sensor. The feedforward control device is included in the digital signal processing device and a feedback control device by a constant amount feedback technique is included in an analog circuit, whereby sturdiness when a loudspeaker is operated is improved. The present system automatically has functions of modelling and filter synthesis. Operation frequency of the loudspeaker can be reduced, and in a different space an accurate low frequency sound volume is yielded, and so parameter drift in operation over long term can be suppressed.