Problems trying to use BFD with HK Amp

Discussion in 'Archived Threads 2001-2004' started by TrevorST, Jan 12, 2003.

  1. TrevorST

    TrevorST Stunt Coordinator

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    I am trying to equalise my SVS and picked up a BFD unit. The problem is there is no way of turning of the main speakers short of removing the cables. When I used the tones downloaded from the site sugested in the snapbug BFD pages it seems a lot of sound in the tones under 80 hz are still coming from the mains, even though the HK is set at 80 hz crossover. Adding filters to the BFD seemed to have no effect on the measured output. I tried having the BFD in both positions green light on and off.

    Anyone have any ideas ???
     
  2. Dustin B

    Dustin B Producer

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    The crossover isn't a brick wall. The sub will play past 80hz and the mains will play below 80hz. You want the mains going, as they will affect the overall frequency response of the sub.

    Remember, boosting any frequency will reduce your subs headroom at other frequencies a corresponding amount. So if at all possible try not to boost anything. Also, if you are trying to boost an actual null, you won't get anywhere. Nulls can't be removed by equalization, you have to stop the offending room mode with room treatments to fix a null.
     
  3. TrevorST

    TrevorST Stunt Coordinator

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    Thanks Dustin,
    I understand that the crossover is not a brick wall but was surprised how much sound still came from the mains at 30 -60 hz. The problem I am trying to fix is not a null but a peak in the 56 - 63 hz range of around 8 - 10 db. I set a filter at each frequency and even using maximum minus gain I could not change the results.
     
  4. Dustin B

    Dustin B Producer

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    You shouldn't have to set a filter at each frequency, 2, 3 at most would be required. Have you tried the various bandwidth settings and made sure you are on the PA filter setting?
     
  5. TrevorST

    TrevorST Stunt Coordinator

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    When I say each filter range I meant one at 56 hz and one at 63 hz. Also I did make sure I was on PA filter (used program 4)but still checked the setting.. Reading the manual and instructions I assumed that the BFD was filtering when the In/Out light is off. But tried it both ways just in case.
     
  6. Frank Carter

    Frank Carter Screenwriter

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  7. TrevorST

    TrevorST Stunt Coordinator

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    I did find the snapbug site and that is what I have been using as a guide.
     
  8. Dustin B

    Dustin B Producer

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    Well, I'm just making suggestions from reading the snapbug site. My BFD is on order and I'll hopefully get it in the next few days. Until I've actually played with one I'm out of suggestions.
     
  9. Doug BW

    Doug BW Stunt Coordinator

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    The in/out light should be ON.

    Also, check this for each filter: Make sure that when you set the Frequency that the little letters that light up next to the big number say "hz", not "khz" (and the frequency should not contain a decimal point).
     
  10. TrevorST

    TrevorST Stunt Coordinator

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    I had just found that that was my problem Doug after wasting a whole day playing with it. What an idiot. Can you confirm when the filters are active when the In/Out button is lit or off. The manual and the snapbug instuctions seem to disagree.
    Thanks
     
  11. Wayne A. Pflughaupt

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    Trevor,

     
  12. Doug BW

    Doug BW Stunt Coordinator

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    The In/Out light should be lit when you want to filter. But that should be easy to check with your SPL meter.

    The setting of the frequencies using the "frequency" and "fine" controls is certainly not the most intuitive thing in the world and is not made any easier by the little "khz" lights. But once you get the hang of it, it's not really all that bad.

    Don't forget to re-calibrate after you've equalized.
     

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