| 摘要 |
A sound reproduction system employs an amplifier system and a speaker (40). The speaker (40) provides two negative feedback signals, one (92) indicative of the current through the speaker voice coil and a second (93) indicative of the velocity of the speaker diaphragm. The velocity signal is provided via feedback path (93) to an input of the amplifier system. The current signal (92) is provided by the second feedback path through a bandpass filter to the amplifier input. The velocity measurement may be derived from a second voice coil (42) coupled to the diaphragm, or may be derived from a piezoelectric sensor coupled thereto. The current signal may be derived from the voltage drop across a resistor (50) placed in series with the speaker voice coil (41).
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