1st FR plot with new 16-46PC+

Discussion in 'Speakers & Subwoofers' started by MikeyWeitz, Aug 1, 2005.

  1. MikeyWeitz

    MikeyWeitz Supporting Actor

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    Can not change the location, so this is where it will have to be. Some weird stuff.
    Ran the plot with ALL speakers running, 80hz xover, Ascend 340 mains good down to 50hz or so.

    Made 1 bfd filter so far with a -14db cut @ 37 hz, badnwidth like 8 or so, and a boostof 8db @ 27HZ, bandwidth @ 4 or so. So far sound better, but won't get to plot again until weekend the earliest. Any thoughts, ideas?

    Sub is located behind my sectional where it curves (which is in rear corner of room) 3' space between sectional and rear wall. SVS is sitting on top of a subdude.

    16-46PC+ pre BFD
     
  2. Victor Ferguson

    Victor Ferguson Stunt Coordinator

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    I would not recommend boosting. IMHO best thing to do is to do a 1hz plot then plug it into the Room EQ Wizard and that will give you a good start.
     
  3. MikeyWeitz

    MikeyWeitz Supporting Actor

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    Thanks Victor, I just ordered a midi cable to dump eq wizard settings into it. I am trying to figure out how to hook up my RS SPL to laptop and then laptop to receiver to do the sweep. May need to find a usb souncard, but having trouble finding one I need on the cheap!

    If I can,t. I will burn a 1hz tone disk.

    What frequncies should I satrt and end with for the 1hz test.

    Thanks.
     
  4. Wayne A. Pflughaupt

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    Mikey,

    I assume the chart is before EQing? Those asymmetrical peaks and dips (i.e., fall or rise faster on one side than the other) are tough – they usually require a minimum of three filters.

    Feel free to boost or cut as needed. You can see from this old post of mine that it’s all academic in the end. Besides, it’ll be impossible to flatten the curve you have there without some boosting.

    16 Hz should be fine in your situation.

    IMO 1 Hz plotting is silly, for several reasons. You will probably be prone to over-equalize trying to get every nook and cranny out of the exceedingly ragged plot you’ll get. Not to mention, it doesn’t make any sense at all to have twenty samples for the first octave (20-40 Hz) and forty samples for the second one (40-80 Hz). Also, it’s more difficult to extrapolate filter bandwidths given in octaves with a 1 Hz plot. It’s much easier when your readings are in fraction of octaves to begin with.

    Most people get satisfaction with 1/6-octave readings. If you’re really picky it won’t hurt to ramp it up to 1/12-octave or even 1/24-octave if you’re really ambitious. Whichever way you go, it makes more sense to keep your readings in fractions of octaves than 1 Hz.

    Regards,
    Wayne A. Pflughaupt
     
  5. Joe Szott

    Joe Szott Screenwriter

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    What program can you use to get a nice plot like that?
     
  6. MikeyWeitz

    MikeyWeitz Supporting Actor

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    Yes Wayne, the chart was prior to plotting. I have not plotted since I made the 2 filterslisted above, but just watched my 1st full DVD (Constantine) and was COMPLETELY blown away. AMAZING Bass like I have never felt/heard before.

    Any advice for my 3rd filter?

    Thanks.
     
  7. Wayne A. Pflughaupt

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    Joe,

    There’s a download for it at the BFD Comprehensive Set-Up Guide.

    Mikey,

    As I mentioned, you’ll need to apply another filter or two to “clean up” the results of the first two.

    I don’t know how to translate the BFD’s bandwidth figures you gave to something more universal (like octaves or Q), but let’s take your 37 Hz filter as a “for instance.” If you used a wide filter, then the low point at 28 Hz was pulled down even deeper. That would need to be addressed with another filter to get it up to where it was, or where it’s supposed to be.

    Or, if you used a narrow filter at 37 Hz, then you were probably left with a new peak at around 50 Hz. That will need to be addressed with another filter.

    Since the 37 Hz adjustment will tend to spills over to the 28 Hz problem, the former should be fully dealt with before you start on the former.

    Regards,
    Wayne Pflughaupt
     
  8. MikeyWeitz

    MikeyWeitz Supporting Actor

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    I follow you Wayne. I will see where I am @ when I replot this weekend.

    Thanks again. So far, sounds GREAT, gues she needs just a little more work.
     
  9. BradJudy

    BradJudy Stunt Coordinator

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    Room EQ Wizard is an excellent free program for measuring sub response. It can do pretty high resolution measurements and includes BFD programming assistance and C-weighting correction if you are using a RS meter as the mic.

    http://homepage.ntlworld.com/john.mu...meq/index.html
     
  10. MikeyWeitz

    MikeyWeitz Supporting Actor

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    In Room eq wizard, what does Q mean (for example, when it creates the filters and has a Q of 4.3?

    How/What does that translate into a BFD setting?
     
  11. BradJudy

    BradJudy Stunt Coordinator

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    Q is the width of the filter. I don't have a BFD, so I don't know what that translates into.
     
  12. MikeyWeitz

    MikeyWeitz Supporting Actor

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    I know what it is, but want to know how it translates to the filter setting in the BFD.
     
  13. Mike Keith

    Mike Keith Second Unit

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    As Wayne stated, don't be afraid to boost, but as I recently found out, it's the narrow filter boost that will cause you problems. Keep the Q on the BFD around 25 and up, too narrow of a boost will cause ringing at that frequency, and ringing is far worse sounding then a dip.
     

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