Mini subwoofer circuit using LF347N

This is mini subwoofer circuit stereo for home using low noise LF347, it can select frequency output filter is 60Hz,50Hz and boost up preamplifier.

Almost everyone like sound realistic, particular the low frequency sound signal is system that commonly widely used. With how to bring out the low frequency signal. from amplifier circuit both left channel and right channel come Enlarge together, And then enter to speakers are designed for Low Frequency, particular sound from the subwoofer speaker, will cause the sound system vibrate up. But increased sound quality. Inevitably requires a more money as well.

How it works
But for those who has less money, you can build a subwoofer an artificial. Our method is simple, Will help raise the low frequency sound signals to considerably higher special. From circuit will see the input signal is entered into the input buffer circuit. Which will provide the signal gain at frequency The output from buffer circuit will enter to low pass filter circuit that will refusing to pass a signal at a frequency lower than 60Hz only. The output of low pass filter will be entered to the mix with the normal signal from the amplifier input circuit, to the signal complete all frequency range.
In figure 1 shown the perfect stereo system circuit. From circuit will seen that IC1a(TL074) has gain at higher frequency than 60Hz = 1 and the amplify rates of the circuit, will gradually increase the frequency below 60Hz. Compensation for the performance of the speaker, at low frequency response reduced.


The output of IC1a(TL074) some one will enter to the low pass filter circuit IC1b and IC2a, which allows only frequencies below 50Hz through.
The IC2b(TL074) is the total output of IC1a and IC2b, joined together, Switch S2 is used to adjust a bass level much or less as needed.

Mini subwoofer parts

IC1, IC2__________________ LF347N OR TL074 or TL084 Quad JFET Input Op-Amp (Wideband)
R1, R26___________________ 47K_____1/4w Resistors
R2, R25___________________270K_____1/4w Resistors
R3, R24___________________56K_____1/4w Resistors
R4, R23___________________11K_____1/4w Resistors
R5, R7, R20, R22____________ 68K_____1/4w Resistors
R6, R21____________________ 36K_____1/4w Resistors
R8, R19____________________ 680 ohm_____1/4w Resistors
R9, R18____________________ 1.6K_____1/4w Resistors
R10, R12, R15, R17____________ 10K_____1/4w Resistors
R11, R16____________________ 390 ohm_____1/4w Resistors
R13, R14____________________ 1.2K_____1/4w Resistors
C1, C12____________________ 0.33uF 50V_____Polyester Capacitor
C2, C11____________________ 0.047uF 50V_____Polyester Capacitor
C3, C5, C8, C10_____________ 0.47uF 50V_____Polyester Capacitor
C4, C9, C13, C14_____________ 0.1uF 50V_____Polyester Capacitor
C6, C7____________________ 0.01uF 50V_____Polyester Capacitor

How to build
In figure 2 Show the PCB design and equipment position. We are equipment installation all the is required by Circuits.
Connection to use it, if pre amplifier circuit and power amplifier as discrete set to connected this circuit before the power amplifier circuit.
If your the amplifier is integrated to connect this circuits into the Aux input.
Note: Due to a bass signal is enhanced more than 10 times so the output may has higher signal than 10 volt, may makes speaker have suffered, in the deployment so it should be extra careful.

Related Posts


I always try to make Electronics Learning Easy.

I love electronic circuit. I will collect a lot circuit electronic for teach my son and are useful for everyone.
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Close Menu