| 摘要 |
<p>PURPOSE:To vary characteristics according to sound pressure from a speaker by adjusting a signal obtained by converting a detection signal, which is proportional to the speed of a speaker driving system, into acceleration, and a signal obtained from an amplifier output through the 1st and 2nd voltage variable resistors. CONSTITUTION:Resistance values of voltage-controlled variable resistors VCA12 and VCA13 vary with a voltage applied through a variable resistor R3, and the internal resistance value is great when the slider of the resistor R3 is at the earth side, and less when at the side of a power source terminal 11. With regard to the amplification degree of an amplifier 3, the feedback degree is set depending upon the division ratio of the resistances R1 and R2, and an MFB feedback circuit 14 with differential characteristics and a bridge 4 are combined together to an acceleration type MFB circuit. Then, the frequency characteristics are varied according to the level of a signal applied to an input terminal 1 to successively vary the characteristics according to sound pressure from a speaker 5.</p> |
