Low/High Pass Filter Questions

Discussion in 'Speakers & Subwoofers' started by James Edward, Jun 1, 2005.

  1. James Edward

    James Edward Supporting Actor

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    I can never get this straight...

    If a sub has a LOW pass filter, and I run my pre-outs to the sub, then back out from the sub to the main-in on my integrated, how does this differ from a HIGH pass filter?

    My interest is in removing the bass signal from my integrated amp if possible, and rely on the sub for bass.

    Thanks for any replies...
     
  2. Wayne A. Pflughaupt

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    Assuming a specific crossover frequency, “high pass” is everything above that point, “low pass” is everything below.

    Another way to keep it straight, they accomplish the opposite of what they’re called: “high pass” filters out the lows, “low pass” filters out the highs.
    In this situation the sub has both low and high pass filters.

    Regards,
    Wayne A. Pflughaupt
     
  3. John Garcia

    John Garcia Executive Producer

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    The easy way to remember, and it's pretty self explanatory: low pass lets the lows pass through the circuitry, and vice versa.

    If the line level output on the sub has a high pass filter built in, you should be OK, but it will very likely be a fixed high pass (not affected by the x-over setting). This may not be a desirable thing, depending on how much bass you are looking to send to your mains. There's a good possibility there is no filter on the line level outputs from the sub.
     
  4. Greg Bright

    Greg Bright Second Unit

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    The other alternative would be to use the speaker level inputs and outputs on the sub. These almost always have a high pass filter built in, usually at 80Hz or so with a 6Db per octave slope. The only drawback is that there may be phase problems with your main speakers. It's certainly worth a try.
     
  5. James Edward

    James Edward Supporting Actor

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    Thank you... I think I've got it straight now. The sub I'm using in my stereo system is a PSB Subsonic 6i, and only has a low pass filter.

    I'm going to order a High Pass Filter from Hsu so that I can keep my integrated amp (NAD C320BEE) from having to reproduce some of the bass frequencies. I love the sound of this amp, but at louder levels it seems to harden up a bit. This should help, since my speakers(PSB Stratus Golds) are supposed to be a somewhat difficult load for an amp.

    Thank you again.
     

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