Two-channel subwoofer circuit

The two-channel subwoofer circuit is connected before the power amplifier. The enhanced bass signal is mixed with the original signal and then sent to the power amplifier to drive
the speaker to play back sound. The amount of mixing is adjustable.
    Figure 9-1" is the schematic diagram of one channel of this circuit.
    The input signal is processed by a fourth-order low-pass filter composed of ICl-a, ICl-b and peripheral components. Its center frequency is
70Hz and the attenuation slope is The rated range is 24dB, and the gain is 8.2dB. Then
it is amplified by a ten-fold buffer amplifier composed of ICI-c and output. The improved low-frequency signal and the original signal are sent to ICl-d by C4 and C4 for mixed processing and then sent to the power amplifier.
frequency amplifier. The mixing amount of the low-frequency signal and the original signal can be adjusted by RP. In order to ensure the fidelity of the original signal after the potentiometer RP is turned off (
the mixing amount of the bass signal is minimum), the gain of the ICl-d mixing amplifier is designed to be OdBo.
    This circuit can It enables double-channel reproduction of the subwoofer, accurate sound field positioning, and its circuit is simple. When making the circuit,
pay attention to the use of high-quality components in the selection of components. Among them, Icl can use four operational amplifiers TL084, or you can choose dual operational amplifiers with better performance
. The circuit is composed of a single operational amplifier. In addition, the two-channel subwoofer circuit requires that the power amplifier connected behind it has a certain power margin. At the same
time, due to the connection of this circuit , the distortion of the entire audio system is inevitably increased.