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 does not have any rules.
This subwoofer circuit set is designed to have a cut-off frequency 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 channel 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 channel 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 known 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 to pass away only.
And the output from pin 1 of IC1b is entered to pass through R9, C9 onto the power amplifier circuit that is designed for driver only the subwoofer loudspeaker
We use the LM7812 IC2 as a 12V dc fixed regulator for this circuit so can use the voltage supply range 12Vdc to 24Vdc as we want.
The diode D1 is a 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 ohms, 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

This circuit requires enough power supply. Do you have this one? If you do not have it. Look:Learn Many Power supply circuits

How to build

Equipment as a 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 Metalized 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 use a capacitor electrolytic C1, C2, C3, C4, and C5 was. And for C7, C8 It replaced with a normal mylar capacitor. Thus helping you save a lot.

Related Posts


I always try to make Electronics Learning Easy.


  1. Hi,Bhaby Boii Sabello and Chrieyz Kile Arhaiza

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

  2. Kunal

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

  3. Kunal

    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?

  4. TSK!TSK!

    your circuit is not working,try to fix it!

  5. 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.

  6. Best

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

  7. kazance

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

  8. sana

    Not working. Don’t waste time on this

  9. trinadh

    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

  10. NIloy

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

  11. pulock

    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.

  12. audioraitan

    good design low pass filter.

  13. umer

    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.

  14. Umer

    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

  15. hilman

    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]

  16. Author has kept superb unknown ideas, that will help most of music lover. It is not only includes huge ideas but also user friendly with figure-out post. If anybody read this article will reinforce to get this. Thanks a million for this post.

Leave a Reply

Your email address will not be published. Required fields are marked *

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