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Subwoofer room response graph..BFD help needed

Discussion in 'Subwoofers' started by dongagon, Oct 13, 2004.

  1. dongagon

    dongagon
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    Hello

    Please find attached the graph for my Subwoofers room response (taken with the fronts on). Can anyone suggest some BFD filter setting (frequency, fine, bandwidth, gain) that i can use in order to acheive the "house curve".

    Kind Regards

    P.S I currently have my speakers set to smal,l and the amps crossover set to 80Hz. I am thinking of changing the amps crossover to 50Hz. That might get rid of the huge peak between 45Hz-89Hz.

    Let me know what you all think
     

    Attached Files:

  2. bass007

    bass007
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    how do you get these measurements? looks complicated...
     
  3. dongagon

    dongagon
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    You'll need a Sound Pressure metre,
    Test tones (at a variety of frequencies) and the spreadsheet available from here: http://www.snapbug.ws/subtestmodel.xls

    You then play each test tone, and make a note of the reading on the Sound Pressure metre.
    Thne enter this reading into the Excel spreadsheet, this will plot your subwoofers response on the graph.

    Its important not to alter the volume on your amp whilst performing the test.

    Hope this helps
     
  4. BassThatHz

    BassThatHz
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    <p>I believe the cause of your graphs anomalies is either a result of having your fronts on while measuring or some really, really nasty room modes. Not to sound negative but, trying to achieve the "house curve" with the graph that you have posted would be nearly impossibly, regardless of the BFD settings. Not too mention damaging to the subwoofer and/or BFD even with the crossover set to 50 or lower.</p>

    <p>Your crossover of 80 should be just fine, try running the measurements with all other speakers off and see if those room modes disappear or reduce somewhat. If they don’t then they ARE room modes caused by bad room placement. If relocating the subwoofer isn’t an option (all else fails) try something like this: Set crossover to (70 or 50) and place these two filters (freq 40, fine +10, gain -4, bandwidth 3) (freq 80, fine +4, gain -10, bandwidth 10)</p>

    <p>By the way, How are you generating the test tones(that could be another source of the problem) What are your room dimensions and subwoofer specs? I think your subwoofer should be able to easily hit an average of 70 to 80db across most of its usable range, cause something very strange is happening at 45hz in your room.</p>
     

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