A signal processing circuit including the signal combining circuit, a stereo audio audio reproducing system including the signal processing circuit, and a stereoscopic audio reproducing system-containing audio-visual reproducing system

摘要

The signal combining circuit 1 has a first input 2, a second input 3 and an output 4 for receiving a signal having the frequency of the audio frequency spectrum. The signal path between the first input (2) and the output (4) has a first transfer characteristic (H1, H3). The signal path between the second input 3 and the output 4 has a second transfer characteristic H2 and H3. The transfer characteristics do not match and this inconsistency causes a phase shift between the signal component passing through the first signal path and the signal path passing through the second signal path. The amplitude transfer characteristic determined by the transfer characteristic decreases at a predetermined frequency or more. There is a phase difference between the phase transfer characteristics where the frequency is reduced. For frequencies below the predetermined frequency, the amplitude transfer characteristic determined by the first transfer characteristic exceeds the amplitude transfer characteristic determined by the second transfer characteristic. By interconnecting the first input 2 and the second input 3, the amplitude transfer characteristic ((H1 + H2) .H3) between the output as a function of the interconnected input and the frequency is almost constant.;The signal combining circuit is used in a stereophonic audio reproduction system for enhancing a stereo image, which forms part of a voice-image reproduction system, for example.