bass attenuator

Discussion in 'The Projects Forum' started by lokeycmos, Apr 2, 2010.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    im looking for some help with an adjustable bass attenuator. the subwoofer on my home theater reciever over powers everything else even with it turned all the way down. i built the attached circuit with no luck. i just couldnt get it to work period. (even just the bass half).i really couldnt find much on this topic on google. im hoping someone can post a super simple passive bass adjustment schematic? thank you much! -joe
     
  2. Bychon

    Member

    Mar 12, 2010
    469
    41
    What you've built seems to be a tone control. If I would start from this, I would unsolder the 3.3k resistor, add a 330 ohm resistor to ground, and put in another 3.3k resistor to connect to the treble pot and the 8.2k resistor. (It's called a T circuit.) You can install a variable resistor where I told you to put the 330 ohm resistor, too.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    That is a Baxandall tone control circuit. Your subwoofer should have its own amp. If so, a volume control to cut the signal into it is more the thing to use.

    A subwoofer is mono. The audio from both channels (ideally) is passed through separate low pass filters to remove sounds above some point, like 80 Hz. Then they are mixed and fed to the subwoofer amp. There should be some control to let you adjust the level of the subwoofer so it balances with the rest of the sound system. Check your manual.
     
    Last edited: Apr 2, 2010
  4. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    mine is a passive subwoofer. i have it turned all the way minimum on the reciever. could i just put a pot in line with it?
     
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    If you connect a resistor in series with the sub-woofer speaker then you ruin the excellent damping of its resonance from the extremely low output impedance of its amplifier. Then the sound will be very boomy, something like a bongo drum.

    You need to see why the sub-woofer volume control in your receiver does not attenuate enough.
     
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