Car subwoofer filter

jacky April 7, 2010 30 Comments

Here is the circuit diagram of a simple subwoofer filter that can be operated from a 12V DC supply. Such a circuit is very useful in automobile subwoofer applications. The circuit is nothing but a low pass filter whose pass frequency can be adjusted between 60 to 160 Hz.
The circuit is designed around the TL072 dual BIFET opamp IC. Out of the two opamps inside the chip, IC1A is wired as a buffer. The left and right audio inputs after mixing is fed to the input of the IC1A using the DPDT switch S1. Switch S1 is the phase control switch which can be used to make the subwoofer in phase with other speakers. When S1 is in position 2, 180 degree phase shift will be induced.POT R7 can be used for controlling the level. IC1B forms the low pass filter whose pass frequency can be controlled by adjusting the dual gang POT R13.

Circuit diagram .

car subwoofer filter circuit


  • Assemble the circuit on a good quality PCB.
  • The circuit can be powered from 12V DC.
  • IC1 must be mounted on a holder.
  • S1 is a DPDT switch.
  • R13 should be a dual gang linear POT.
  • C5 and C6 must be polyester capacitors.
  • POT R13 can be used for adjusting the pass frequency.
  • POT R7 can be used for adjusting the level.
  • tom & jerry
    August 29, 2015

    both ic has given 12v supply?

  • tom & jerry
    August 29, 2015

    where to given 12v supply in this filter circuit

  • awais mughal
    January 11, 2015

    HI SIR,

  • grtblu
    September 18, 2014

    If you want powerful sub-sub sound, put a linkwitz filter on the front end. This will overcome a poor performing speaker by putting a gain boost on the lower frequencies. If your speaker rolls off (for example) below 40Hz, you can make it perform down to 20 HZ if you want using the linkwitz filter.

  • Mohsin
    September 12, 2014

    can the inout be from any weak audio source or does it need to be pre-amplified? because it provides weak bass as compared to the other two channels. I made a 3 channel amplifier and fed output of this circuit to 3rd amp.
    I used this amp circuit

    February 13, 2014

    Hello sir, i make this circuit on split supply, but i want its work with singal supply.can u email the pcb layout or any webside who has pcb layout. If u help me then my 2.1 soundsytem complete.

  • alexander
    January 14, 2014

    I like this circuit, please sent to me pcb for this project, thank you.

    • omer
      August 10, 2014

      I can provide you its PCB as well as its tutorial videos for only 5$ ….

  • cooool
    May 26, 2013

    Hi sir this circute is to be connected before amplifire or direct subwoofer please reply me

    • omer
      August 10, 2014

      yes this circuit is connected before the amplifier and you can use it in any amplifier to make it a subwoofer amplifier..
      for more information please contact me

  • manish
    November 16, 2012

    can i connect it to any amplifier or there is a specific amplifier???

    • omer
      August 10, 2014

      you can connect any amplifier with it

  • yugandaraj
    June 20, 2012

    HI.. this can be done using a simple RC lowpass filter adding input of power amplifier ..

    • omer
      August 10, 2014

      yes you can obtain low pass sound with RC filter but it does not give effective bass as this opamp based circuit gives…

      • December 3, 2014

        Hello ser can you send me a pcv design for these circuit because I’m interested to make these project.

  • sugiman
    August 16, 2011

    it was a ampli there?

  • Patrick MAGS
    June 8, 2011

    the output of the subwoofer needs to amplifi…..
    the circuit given is a filter circuit….

  • ashok kumar
    December 20, 2010

    hi, im ashok
    1,do we need to amplify the subwoofer output or we can feed it directly to it?
    2,if we have to amplify it ,then wats the amplifier circuit?
    3,moreover the pin 8 is supply but it is connected to 3rd pin via 100k, is that rite?
    4,is the input is preamp input or amplified input?

    anybody plz reply,,,,,
    my email is

    • omer
      August 10, 2014

      yes you need to amplify its out because this circuit is only a filter and has very few mili volts output… so it must be definitely amplified.
      There is no specific circuit for this amplifier you can use it at the input of any amplifier

  • abdulazeez
    December 15, 2010

    pls. Ineed i complete circuit on an automatic voltage stablizer

  • Boris
    September 28, 2010

    Hello, greetings from Argentina, I’m interested in making this circuit. I’m not good in the design of PCB’s, will have a chance to send me the pcb for this circuit to my mail?
    Thank you!

  • seetharaman
    March 1, 2010

    Hi Pin No 8 of IC TL072 should be connected to +12V. Common zero volt tp pin no 4.

  • Raptor
    February 28, 2010

    i think this will take power from the audio source itself ,,

  • February 16, 2010

    I saw the circuit diagram of car sub woofer but I confuse which poit apply 12v DC.

    • omer
      August 10, 2014

      Pin number 8 is the point where you connect the +12V DC

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