| 摘要 |
A sum speaker is placed behind a panelboard opening in an enclosure. Across the front of the opening and normal to the panel is divider means having speaker apertures therethrough. A baffle member at least as wide as the opening extends across the distal edge of the divider means and parallel to the panel board. Difference speakers are positioned on opposite sides of the divider means, facing in opposite directions. The sum speaker produces sound corresponding to the sum of the left and right stereo channels, while the difference speakers produce sound corresponding to the difference between the left and right channels, with the diaphragms of the difference speakers moving simultaneously in the same direction. This is achieved by a matrixing means comprising an autotransformer. The ends of the transformer coil are connected respectively to the ungrounded output terminal of the left and right channel amplifiers respectively. The difference speakers are connected across the ends of the autotransformer. The sum speaker is connected between the transformer centertap and the grounded output terminals of the two amplifiers. In one embodiment the sum speaker panelboard and the divider are vertical. In another embodiment the sum speaker panelboard is horizontal and the divider means comprises four wings positioned as a Greek cross, with different speakers on each of the wings.
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