low pass filter, subsonic, phase, level....

Discussion in 'OT Technology' started by Mojo, Mar 18, 2005.

  1. Mojo

    Mojo New Member

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    i dont know my settings too well but i would like a simple explanation of which each does and how its used.

    low pass filter
    subsonic
    phase
    level/gain


    better yet, a link would even help:)


    thanks all
     
  2. P07r0457

    P07r0457 New Member

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    low pass filter : A type of crossover that allows anything below the set frequency go through, but blocks anything else. Useful on amps that run subs.

    Subsonic filter : A type of filter used in-conjunction with a LPF that will prevent frequencies below a set number from going through. Useful for ported enclosures.

    Phase : Used to change the alignment passed through. 180 degrees would effective reverse the phase, giving the same effect of swapping the + and - leads.

    Level/Gain : value to amplify the source. Search some sites like sounddomain on a how-to for setting your gains with a multimeter... You can run some simple mathematical equations given your speaker's specs, and set your gains properly using an AC voltmeter.
     
  3. Mojo

    Mojo New Member

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    on the subsonic filter, is it best to match the dBs with the LPF when setting those around? i dont know how to adjust it, can you give me an example of this? i have a ported/vented enclosure but dunno how to take advantage of it :(

    as for phase, itd prob be best not to toggle with that eh? i just leave it @ 0 degree

    i have no tool or idea to measure my gain/level, but i always leave it a tad above the minimun level. therefore, thats like 1V-2V. i do notice that the sub pounds harder when the level is lower though


    thanks for the help!


    if it matters, my sub is kicker solobaric 15" L5 powered with a brutus bx500d class-d mono amp
     
  4. calliz

    calliz New Member

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    *Clarification

    Low Pass Filter: That's an equalization setting. If you think about the low to high frequencies, this is going to roll-off (get rid of gradually, depending on where and how hard you set the slope) any frequencies above the low frequencies you specify. As jollyogre said, it's used for subs because you just want to isolate the lower frequencies that subs are made to spit out.
     
  5. 04

    04 Guest

    On the subsonic filter, I would set the slope (dB per octave) as high as possible. I would set the frequency to somewhere around 1/4 octave lower than the subwoofers tuning frequency.

    The phase is relative to the other speakers in your car. I'd probably leave it set to 0 degrees too, unless you notice a huge suckout in the frequencies around the crossover point.

    Often times, the gain structure is reccomended to be set to a 3:1 voltage ratio. That is, if the headunit has 2v preamplifier outputs, you'll want to set the gain on the amplifier so that it clips with a .67 volt input. You'll get a 10 decibel overdrive, but with most music, the clipping wont be audible because of the dynamic nature of music. Of course this is also relative to your speakers, and if they are playing off the headunit, you'll want to set the gain to correspond with them (if you want a somewhat flat frequency response).

    I dont understand how your subwoofer is louder when the level is lower though?
     

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