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BFD part 2

Discussion in 'Home Cinema Speakers' started by petrolhead, Nov 24, 2003.

  1. petrolhead

    petrolhead
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    This is a big learning curve and after listening to what you guys have said decided to start again

    [​IMG]

    This time the Processor is set to PLII + THX as suggested.

    If you can be bothered I would appreciate some ideas as to where to start.

    Thanks
     
  2. codling

    codling
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    try for now

    freq= 40hz
    bw= 20
    gain= -12

    i would post a pic of my results but i dont know how to:confused:

    carl:)
     
  3. petrolhead

    petrolhead
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    Results to date

    [​IMG]

    These were the filters I used

    [​IMG]

    The little hump at 40htz is a pain but to get rid of, seems more trouble than it's worth. I tried adding an extra filter at 40htz, 5BW and -5GAIN but it created an unusual drop at 50htz

    This http://www.pellis.co.uk/progs/mine.zip was the spreadsheet that helped to get the results
     
  4. Ryan

    Ryan
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    2 points petrolhead.

    1. Your bandwidths are much too high. Try and keep them narrrow.
    2. where is you LFE cutoff. If it's at 80hz then you shouldn't need to have any settings over 80hz.
     
  5. Apocalypse

    Apocalypse
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    Petrolhead - Yesterday I got isolation platforms for my sub so I started the BFD process from scratch and documented it with pictures etc, it'll be ready for viewing today hopefully.
     
  6. petrolhead

    petrolhead
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    Ryan you will notice there are no Frequencies over 80 switch on.

    The LFE is set to 80.

    How would you have gone about taming the origional plot?

    Apoc, look forward to your results
     
  7. Apocalypse

    Apocalypse
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    BFD II

    Meant to place some basic hints and tips but forgot so I'll do it here.

    1, A dip or peak that cover 2 squares on the graph is roughly a bandwidth of 10, if you use that as a guide you'll get some idea of what bandwidth to use in the future.

    2, If you use a positive Gain you have to redo the peak limit in the bypass mode again as boosts increase the BFD's output. Or even easier just reduce the Amp/Processor's LFE level by however much you think is needed

    3, Don't get stressed over getting a perfect curve, you will not notice minor troughs and peaks in the real world (minor = below 3Db)

    4, Many people suffer from a dip near the 80Hz frequency, this is due to the Xover and not much can be done about it with a BFD, equally the sub has less influence near 80Hz and would probably be unable to cure a huge peak at or near 80Hz (assuming you have a 80Hz Xover)

    5, Positive Gains are to be used sparingly, the more power your sub has the more you can get away with..............within reason

    Phil
     
  8. sticker

    sticker
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    Phil,
    I see the bath mat is still present & correct :D :D

    Regards
    John
     
  9. Apocalypse

    Apocalypse
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    LOL, I knew there was something I should of done before taking the pictures, the BFD is now in a proper rack though so I'm only half an idiot :laugh:
     

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