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BFD/PEQ experts I need filter help. I'm lost!


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#1 of 2 Bill**H

Bill**H

    Stunt Coordinator

  • 53 posts
  • Join Date: Nov 25 2002

Posted April 26 2004 - 02:21 PM

I have been using PEQ ver 1.05b for the last 3 days and changing the filter settings to see if I can get my sub to sound better with a house curve.
http://www.pvconsult...udio/eq/peq.htm

The BFD is on it's way here. I thought I could get my filters all set and just insert them when it get here. I'm lost! I need some help from the experts.

My room is 11x33x8, 2900 cubic feet. I have moved the sub around and I get the best response next to the TV. The sub is a Tempest Adire Alignment. I found the response to get a little flatter when I rotated the sub 90 degrees. That changed the way the speaker and 2 ports were in relation to the walls.

These are my Radio Shack SPL numbers, crosover set to 80 with only the sub on;

----------uncorrected--------------corrected--------
17.8 Hz-----71.5--------------------81.5
18.8--------73.25-------------------81.75
20.0--------76----------------------83.5
21.1--------80----------------------86.5
22.4--------81.75-------------------87.75
23.7--------82.5--------------------88
25.1--------83----------------------88
26.6--------82.5--------------------87
28.2--------84----------------------88
29.9--------86.5--------------------90
31.6--------86----------------------89
33.5--------87.5--------------------90.35
35.5--------87.75-------------------91.5
37.6--------90----------------------92.75
39.8--------90.5--------------------93
42.2--------86----------------------88.4
44.7--------87.5--------------------89.5
47.3--------92.75-------------------94.5
50.1--------93.75-------------------95.25
53.1--------90.5--------------------92
56.2--------84.75-------------------86.25
59.6--------87.75-------------------89.25
63.1--------87.75-------------------89.25
66.8--------90.75-------------------92.25
70.8--------89.5--------------------91
75.0--------89.5--------------------91
79.4--------92----------------------93.5
84.1--------91----------------------92.5
89.1--------84.25-------------------86
94.4--------81.25-------------------83.05
100.0-------83.5--------------------85.5

These are the filters I set to see what it looks like. I can not seem to make the curve look good.

Filter.....Fine.....Gain.....BW x/60.....Net Frequency
25Hz........6........2.........6/60.........26.8
37Hz........8.......-11.......26/60........40.6
50Hz.......-2.......-10........8/60........49.1
42Hz........2........9........17/60........43
80Hz........6.......-16.......68/60........85.3
100Hz......-6........8........12/60........93.5
25Hz.......10........3........120/60.......28.3
50Hz.......10........3.........75/60.......56.1

I'm not sure I can use some of the numbers I picked.

If you know your way around the Behringer Feedback Destroyer or the PEQ ver 1.05b would you please help me with the filter settings.

I've been spending so much time on this I almost fell asleep driving home from work today and it's only Monday...


Thank You,

Bill

#2 of 2 PaulT

PaulT

    Supporting Actor

  • 932 posts
  • Join Date: Oct 28 2002

Posted April 26 2004 - 03:43 PM

Bill, I'm definately no expert as I have been playing with my BFD for less than a week (that sounds funny Posted Image). Here are some of the things I went through:

I also started with my measurements at 1/12th Octave steps and used PEQ 1.05 to rough in the filters. Some of yours didn't make sense, however, plugging your readings in and using these filters I was able to get flat response in PEQ:

Freq, Fine, Gain, BW, Net Freq
25, 4, 3, 20, 26.4
40, 0, -5, 13, 39.9
40, 6, 6, 9, 42.8
50, -2, -6, 12, 49.1
50, 10, 5, 5, 56.4
63, 0, 2, 5, 63.2
63, 4, -2, 5, 66.2
80, 2, -4, 7, 81.5

Your house curve can start at 80Hz and increase slowly to your max bottom frequency.

Be aware that your room will have a great affect on the filters, and PEQ is just a rough guide. Once I had the PEQ settings, I used the subtestmodel spreadsheet and 1/6th Octave tones to plot the final response with the filters in. Back to the PEQ program to zero in on the frequencies, then more 1/6th Octave runs. Took about 4 runs in total to get a fairly good curve going.

Definately read Sonnie Parkers website at http://www.snapbug.ws/bfd.htm

There are many other more knowledgeable people on this forum who can help you. Do a search on BFD in the DIY Forum as well for a huge amount of info.

Good Luck
"One of the problems of taking things apart and seeing how they work--supposing you're trying to find out how a cat works--you take that cat apart to see how it works, what you've got in your hands is a non-working cat." -- Douglas Adams