An Automatic Graphic Equalizer for Car Audio Systems

Although a graphic equalizer is almost essential for high quality automobile audio systems, consumers, not knowing the actual data of the field in automotive cabins, often have difficulty making a satisfactory adjustment. We have developed an automatic graphic equalizer with parametric-state band pass filters controlled by a microprocessor which makes it possible to automatically and precisely compensate the basic transfer frequency characteristics (peaks and dips) for each speaker at the selected listening position and shows the settled equalization curve on an LED display. The equalizer, after establishing a flat frequency response, also allows the user to manually modify the frequency response according to his preference.