Introduction to several methods of making subwoofer circuits

Photocoupler

(l) The dynamic subwoofer circuit STDTD circuit is shown in Figure 9-36. This is an improved Aihua XI strong circuit, which is connected to the two ends of the amplifier volume potentiometer, and the bass boost varies with the volume. It has a 15-20dB boost for bass below 85Hz. The basic circuit and the connection method are: disconnecting the signal line at the upper end of the original amplifier volume potentiometer, and connecting the IN end of the circuit, so that the pre-stage signal is buffered by Al and sent back to the upper end of the original potentiometer. WH, after another Butterworth filter composed of A2 and peripheral components, the bass signal is amplified by A3 and output to the center tap of the original potentiometer. Changing the value of R. can change the subwoofer component. The value of RO is 1/3 of the resistance of the original volume potentiometer. If the potentiometer of the original machine is lOOkfl, it takes 33kn. Connect a capacitor of 1000 to 1f500pF at both ends of WH and wo in the circuit. This dynamic control is equivalent to the circuit having equal loudness characteristics. Even at low volume, the treble is still delicate and the bass is deep and powerful. When making, all the leads are as short as possible. If it is too long, it is required to use the shielded power supply with 12~15V after voltage regulation. If the power supply with dual power supply is better, the circuit and the printed board should be changed accordingly. This circuit is not effective in the way of using voltage to control the volume, such as TC9153.