| 摘要 |
Typically, changes in timbre in an audio reproduction system use analogue or digital filters, either shelving filters (as in the case of bass, treble and loudness controllers) and/or peaking filters (as in the case of speed-and noise-compensation in automotive systems). A problem associated with this implementation lies in the audibility of the phase shift caused by these filters. According to the invention, this and further problems are solved by utilising the crossover network of the system itself-with level adjustable output signals-to attain desired timbre and/or dynamic range adjustments and hence avoiding undesirable phase effects of the traditional bass and treble control filters. An input signal ( 18 ) is according to an embodiment of the invention divided by a cross over network ( 20 ) into a number of frequency bands and applied via level control means ( 21, 22, 23 ) and separate power amplifiers ( 24, 25, 26 ) to loudspeaker drivers ( 27, 28, 29 ). In this manner, the mentioned phase shifts can be avoided and by proper control of the level adjustment means by a frequency-dependent analysis and weighting network ( 30 ), desired adjustment of timbre and dynamic range of the audio reproduction can be achieved. Also control dependent on vehicle speed and/or background noise can be incorporated into the system.. |
