| 摘要 |
A sound reproduction system of the MFB-type (motional feedback), comprising an amplifier and a loud speaker system, the woofer of which is provided with a transducer producing in the lower frequency range a feedback signal proportional to the accelerations of the woofer membrane. The loudspeaker system is provided with a filter connected to the main signal input and designed so as to produce a reference signal in accordance with the expected ideal transfer function of the woofer and its associated crossover filter. This reference signal, alone or superimposed by the output signal of the amplifier, is fed to a comparator in which the reference signal is reduced by the transducer signal (or vice versa), whereby a differential signal is produced and fed to the amplifier as a feedback signal either directly, if it is already superimposed upon the amplifier output, or with addition of this output, whereby a very efficient and optimal feedback is obtained, tending to correct any deviation of the woofer operation, in amplitude or phase, from the ideal transfer function thereof. The respective amplifier and loudspeaker systems are usable in a compatible manner in connection with conventional respective loudspeaker and amplifier systems, so the invention also comprises separate audio signal producing apparatus and loudspeaker systems prepared for cooperation according to the invention.
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