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Cheap car subwoofer filter circuits

This car subwoofer circuit set Suitable for use with a great car audio system. Since this circuit is designed to operate with a 12 volt DC power. But if you put it to use with a home stereo, It do not have any rules.
This subwoofer circuit set is designed to has a cut off frequencies of 200 Hz. If you are not satisfied, you can change the C6, C7, C8, new, follow the table below.

Cut off frequency piont
60 Hz
100 Hz

How it works
The left cannel input signal is entered pass through capacitors C1, C3 are the output Signal to the original circuit. (Or rear left in the car). And the right cannel input signal is entered to C2, C4 to the original circuit. (Or rear right in the car).
Two resistors R1 and R2 will be mixer audio signal the left channel and the right channel both together. Then next wire connects to C5. This capacitor is also know as the coupling capacitor to inverting input of M5218A (IC1a).


The VR1 serves as a set of IC1a gain with much or less as you want.
The output signal is entered pass through the low pass filter circuit that consists of R5, R6, R7, R8, C6, C7, C8 and IC1b Which will allow low frequencies under 100 Hz passed away only.
And the output from pin 1 of IC1b is entered to pass through R9, C9 on to the power amplifier circuit that be designed for driver only the subwoofer loud speaker
We use the LM7812 IC2 as 12V dc fixed regulator for this circuit so can use the voltage supply range 12Vdc to 24Vdc as we want.
The diode D1 is protector connection voltage supply that wrote terminal that it can damage the IC1.


The detail of parts

IC1_______________________________M5218A or 4558
IC2_______________________________LM7812 IC-regulator 12V
R1, R2, R3_______________47K_______Resistor 1/4W 1%
R4, R5, R6, R7, R10_______10K_______Resistor 1/4W 1%
R8______________________20K_______Resistor 1/4W 1%
R9______________________100 ohm__ Resistor 1/4W 1%
C1, C2, C3, C4, C5________ 4.7uF 63V _see text
C6______________________0.33uF 63V see text
C7______________________0.27uF 50V see text
C8______________________0.027uF 50V see text
C9, C10__________________10uF 16V see text
C11_____________________0.1uF 63V see text
C12_____________________ 100uF 16V Electrolytic Capacitors
C13_____________________ 100uF 25V Electrolytic Capacitors

How to build
Equipment as circuit whole, can be placed on the PCB as shown in Figure 2. Then we can connect the voltage to the circuit. For immediate use.
This circuit is designed to the highest quality. When we use a capacitor is best, such as type of Metalize Polyester, Poly Carbonate etc., so the price is quite high.
But if you want a cheap and acceptable sound quality is slightly lower.
It may be use a capacitor electrolytic C1, C2, C3, C4 and C5 was. And for C7, C8 It replaced with normal mylar capacitor. Thus helping you save a lot.

If you like this project. Please buy here.


1. Jameco Electronics : a leading electronic components distributor for over 35 years

This Post Has 19 Comments

  1. does your circuit works properly??
    please reply because i need it as soon as possible.

    thanks ..

  2. Hi,Bhaby Boii Sabello and Chrieyz Kile Arhaiza

    a pin 2 and pin 3 of VR1 is joint together.
    Please see in PCB layout.

  3. Sir, I have made this project but it is not working,I use M5218L IC and it is SIL-8. plz help me.

  4. this is I further want to know that what about the pins 1,2,3,8 of 1st ic and the next ic’s pin 4,5,6,7.

    i use 9v battery , will it work with this much of volts?

  5. your circuit is not working,try to fix it!

  6. Hi,Bhaby Boii Sabello
    Yes, VR1 is pot as symbol. so 2nd leg will connected to others leg you can see in figure PCB layout.

  7. I got warning>> power pin IC1 v+ connected to GND.How to fix?

  8. whether the input of the amplifier can ride boosted output from the radio of 20w or not? Thank you.

  9. Not working. Don’t waste time on this

  10. Bro I’m new to electronics and could u please suggest me, from where should I start my circuit and I’m a bit confused with your pcb layout please reply me soon

  11. Hi, bro..
    I made this circuits, but it’s not working properly. Would you please help and fix this problem?

  12. excellent circuit. working great. i used 4558 as op-amp and dual power supply.and added a r-c high pass circuit on it’s L-R channel out put. value is .1mf and 47k. this circuit produce good quality lower bass with high gain.

  13. good design low pass filter.

  14. I made this circuit and works well but not at higher input volumes.
    First try at breadboard or veeroboard and then it will be easy on PCB.Also you can alter the circuit easily on bb. or vb. as you wish.

  15. I made this circuit and works well but not at higher input volumes.
    First try at breadboard or veeroboard and then it will be easy on PCB.Also you can alter the circuit easily on bb. or vb. as you wish.I use 9v battery so no need for regulator part

  16. dear sir… nice post… and it works for me, i’m glad to say thanks a lot.
    but i need a guide how to add volume control? please answer as soon as you can to my email [email protected]

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