BFD Assistance?

Discussion in 'Home Theater Projects' started by Brian Henchey, Nov 17, 2003.

  1. Brian Henchey

    Aug 23, 2000
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    Based on the user response in the forum, I purchased a BFD several months ago and experimented with equalizing twin SVS 20-39PC+'s (e.g., lots of trial and error). I have since upgraded the PC+'s to one B4+ and am ready to start the process all over again. Final position of the sub in the room is fixed (due to its size--man, you would not believe how heavy this thing is). Would any knowledgeable soul mind giving me some pointers on where to start tweaking--I still don't seem to have the frequency/gain/bandwidth relationship worked out? I have posted the SPL results from the uncorrected frequency response below (obtained from the Snapbug-linked Excel spreadsheet).

    Thanks in advance,

    Raw (but corrected for RS SPL meter):

    16 78
    18 80
    20 76
    22 81.5
    25 85
    28 88
    31.5 85
    36 78
    40 75
    45 89.5
    50 94
    56 98
    63 98
    71 84
    80 84
    89 83
    100 81
    111 78.5
    125 68
    142.5 71
    160 79
  2. Ronnie Ferrell

    Ronnie Ferrell Second Unit

    Jul 16, 2002
    Likes Received:
    I could never figure out that spreadsheet on snapbug.

    Download Tony's spreadsheet and test tones HERE.

    He uses 1/12 as opposed to 1/6 octave tones. (More samples over a small span!)

    His spreadsheet takes a lot of the "trial and error","guess work","figuring what the heck you are doing" out of the equation.

    After you enter your data, you use up and down buttons to tweak your filters. You see the actual changes on a graph and it tells you what to enter into the BFD. You don't have to do any of the math!

    You can see my examples in this post here.


    Above, the dark redish line is my graph with first sample of data. The green line shows the actual filters I have set at the bottom of the shot. Notice the check marks by the filters I have turned on and set by using the up and down arrows. The purple line shows what my curve will look like after I apply the filters I have come up with.


    This is my actual graph after setting the above filters. Notice how close Tony's program projected my outcome. Its not exact but sure is in the ballpark!
  3. Brian Henchey

    Aug 23, 2000
    Likes Received:
    Great! Thanks for the link!

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