METHOD AND CIRCUIT FOR DETECTING COUNTER ELECTROMOTIVE VOLTAGE OF SPEAKER DRIVE CIRCUIT IN AUDIO SYSTEM

摘要

PROBLEM TO BE SOLVED: To improve frequency characteristics, distortion rate, voice hearing sense and power consumption by detecting a counter electromotive voltage generated on a voice coil through an extremely low impedance. SOLUTION: The extremely low impedance such as a resistor Rx in the almost 1/100 degree of voice coil impedance, for example, is inserted on the final step ground side of audio amplifier for directly driving the voice coil. The voltage generated at the terminal of this resistor is (corresponding to the counter electromotive voltage) is inputted to a positive or negative feedback enabled phase discriminating operational amplifier. The output signal of this amplifier is fed back to the output step of audio amplifier on the condition of fixing or varying it.