| 摘要 |
A variable gain amplifier receives an input electrical audio signal and has its gain controlled by a vehicle speed signal representative of the vehicle speed. The signal provided by the variable gain amplifier is coupled to a manually set volume control that is coupled to a power amplifier that drives a loudspeaker. According to a specific form of the invention the manually set volume control is an element in a dynamic equalization circuit that alters the equalization in the bass frequency region typically below 200 Hz in accordance with the setting of the control to provide more boost at lower settings of the volume control.
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