| 摘要 |
<p>PURPOSE:To improve cut-off characteristics by providing a notch filter in the attenuation area of a frequency branching filter. CONSTITUTION:A network filter for a three-channel speaker consists of low-pass filter 1, high-pass filter 3 and a subtracter circuit. Its characteristic is 12dB/Oct as it is. When the out-off frequency of low-pass filter 1 is 800Hz, notch filter 2 of a frequency (2.9kHz) nearly three times as high as it is provided and when the cut-off frequency of high-pass filter 3 is 7kHz, notch filter 4 of a frequency (1.7kHz) nearly one third as high as it. As a result, cut-off characteristics of the low-frequency L side and high-frequency H side can be made steep. Although each filter has a bounce part at its output, it is damped by approximate -20dB to eliminate an influence upon the sense of hearing, so that composite transfer characteristics within + or -1dB can be attained on the whole.</p> |
