Prefix for obtaining pseudo-quadraphonic sound. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Prefix for obtaining pseudo-quadraphonic sound. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Audio equipment

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The action of the set-top box is based on the extraction of spatial information from stereo signals and its production by two additional (rear) speakers. In addition to the elements for extracting spatial information, the prefix contains circuits for frequency signal conversion and switching. Connect the set-top box to the output of the AF stereo amplifier.

Prefix for obtaining pseudo-quadraphonic sound

In the initial position of button S2, the auxiliary speakers B3 and B4 are switched off and the stereo program is played back as usual. When this button is pressed, additional speakers are connected to the output of the AF amplifier and reproduce spatial information (it is highlighted due to the counter switching of the speakers). The level of the signal reproduced by the additional speakers is adjusted with the S3 button (when pressed, the level decreases).

The S1 button expands the capabilities of the set-top box. In its position shown in the diagram, the speakers B3, B4, in addition to spatial information, also reproduce parts of the stereo signals of the left and right channels.

This improves the sound of monophonic programs (so-called surround sound) and programs with little spatial information in the left and right channel signals. When the button S1 is pressed, the loudspeakers B3, B4 reproduce only spatial information.

As additional ones, you can use the simplest loudspeakers with one head (4GD 35, ZGD-28, 4GD-8E, etc.) placed in a box with an open rear wall. The power of the additional loudspeakers can be 2...3 times less than that of the front speakers (B1, B2).

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