A little help setting up my BFD?

Discussion in 'Speakers' started by Kevin_Wadsworth, Oct 15, 2003.

  1. Kevin_Wadsworth

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    Hey guys, I’m looking for a little help in making sure that my BFD is set up right. I’ve read the manual, the excellent snapbug web site, and several threads no this forum. I like to think that I’m a reasonably tech-savvy guy, but it seems like I might be missing something obvious.

    After measuring my room response I found the usual dips and humps in frequency response. I downloaded one of the spreadsheet utilities for simulating the response after applying filters and put those into the BFD on channel 4 (I did check and make sure that all the filters on channel 4 are set to PA). I pressed the store button twice to save all my settings and everything seemed as it should be. However, when I re-tested the frequency response, nothing had changed - all the same peaks and dips were still there. I realize that the spreadsheet predections probably won’t be completely accurate, but it seems like putting all the filters in should at least change something.

    When re-testing, the In/Out light and the Engine L and Engine R lights are all lit green. Other lights are all out. Any thoughts? Am I doing something completely wrong? I’ll probably try setting up another channel with a single filter with a 20-30 dB drop at 40 Hz just to see if I measure a change, but Ithought I’d post here for advice as well.

    -Kevin

    P.S. On another note – I’ve read how much subwoofer placement can affect your frequency response, but I was surprised by just how much. I had two 25 dB dips (70Hz and 80Hz) that were ameliorated simply by moving the sub 6 inches or so. Amazing.
     
  2. ChuckRG

    ChuckRG Agent

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    You can actually test this in real time. Run a signal thru the BFD set up any kind of filter (PA) and then change the gain and see if you hear any difference.

    If you set up multiple filters then that many lights should be lit in the horizontal row of lights for that channel. If not, then something else is incorrect.
     
  3. Kevin_Wadsworth

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    Thanks, Chuck - I'll try that as soon as my wife finished watching reruns of Stargate SG1.

    I did put in 12 filters and all the red lights are on on the BFD.
     
  4. Bill Polley

    Bill Polley Second Unit

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  5. Frank Carter

    Frank Carter Screenwriter

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    Did you overlook pressing the filter mode button and setting it to PA for every filter you set?
     
  6. Mike*D

    Mike*D Auditioning

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    I ran into the same thing while calibrating my PB2+. The filters I set on the BFD were not having any affect on the humps and dips in my room's frequency response. What I discovered was that while dialing/changing the frequency to be filtered, I thought the BFD's readout said 63hz,for example, but in fact it read .63khz. The decimal point and the hz/khz are very small and easy to miss. Check your filter settings again to see if you have done the same. After re-calibrating with the BFD, my PB2+ is flat +/-2db from 20-100hz. Very pleased with the BFD.
     
  7. Kevin_Wadsworth

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    Bill - that's the web page I used when setting up the BFD, but thanks for posting the link again.

    Frank - nope, I didn't verlook that.

    Mike - I think you may be on to something. I just looked at the number and didn't pay attention to andthing else when setting the frequency. I thoguht the readout was 3 digits, so 630 Hz would read "630 Hz", not "0.63 kHz". I'll have to check that out when I get home tonight.
     
  8. MichaelDDD

    MichaelDDD Supporting Actor

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    Small favor to ask, please. Can someone please either host or email me the contents of that "Snapbug" link?

    Our DNS server doesn't recognize that domain and won't link up with it. [​IMG] Thanks. I'm looking into the BFD as well.

    All rooms have humps and valleys; the Results vs. Price ratio on this thing is very good.

    ps
    I've made that mistake w/digital EQs in the past. .1000KHz is NOT 1.000KHz...[​IMG]
     
  9. Heath_E

    Heath_E Stunt Coordinator

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    MichaelDDD, I sent you an email.
     
  10. Mike Nep

    Mike Nep Stunt Coordinator

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    I agree with Mike D. I had the same problem with the hz/khz thing and was going crazy wondering why things wouldn't change when I conducted freq. readings. This is one of the first things you should check before you go any further. Also, you really need to be in front of the BFD when reading the snapbug info or any other info. Print it out and do everything step by step. Once you understand the workings of the BFD, making changes is simple. As for sub placement, you're right that small changes make huge differences. Simply walk around your room when playing a frequency and you'll notice that some areas are completely void of any sound whatsoever. Kinda cool and scary at the same time.
     
  11. MichaelDDD

    MichaelDDD Supporting Actor

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    Heath_E, Thank you very much. I got the .pdf. [​IMG]


    I was going to start a thread, but since the experts are already here, I'll ask here, if that's OK. :b

    I know smoothing the peaks and valleys in sub response is a good thing for music, but could it have the opposite effect for movies? Could you smooth things out TOO much, and reduce the impact of the sub?

    I appreciate the info.
     
  12. MichaelDDD

    MichaelDDD Supporting Actor

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    One more thing, please. Can someone please email me the "subtestmodel.xls" Excel workbook? Again, I can't get to the Snapbug website. Thanks!! I already have the tone generator program. My computer speakers do not like a 30Hz tone at all. :evil:
     
  13. Mike*D

    Mike*D Auditioning

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    MichaelDDD, I sent you an e-mail with the subtestmodel attached.

    I believe that the flatter the sub frequency response the better for music and movies. There is a noticeable improvement in both since equalizing with the BFD. Certain movie scenes that had a boomy, unpleasant quality because of my room acoustics are now smoothed out and completely enjoyable.
     
  14. MichaelDDD

    MichaelDDD Supporting Actor

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    I got the .XLS file, Mike; thanks very much. [​IMG]

    I skimmed through the whole BFD setup/tuning .pdf. All I can say is "Whoa, that's a lot of steps!"

    I only perused the setup document...I'm still kind of confused how and what exactly to do and put into the Excel spreadsheet.

    I assume it'll all be clearer once I give it a thorough read thru. I look at it like this; "$125 for the BFD...how can I go wrong?" [​IMG]
     
  15. Kevin_Wadsworth

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    Mike D - Yep, I checked last night and I had a bunch of filters set for 250 - 1000 Hz. No wonder it wasn't affecting the sub response. I changed the filters and they certainyl have an effect. Response went from +/- 20 dB to +/- 15 dB, still a lot of work to do. I've still got what looks like some bad nulls, but I'm limited in places to put the sub.

    MichaelDDD - I thought the same thing you did: "Wow, this is complicated!", so I had the snapbug website up on my laptop sitting in front of the BFD. However, it actually is quite easy to program the thing once you figure out what the butons are for.

    In response to the question whether the frequency response can be too smooth, the answer is that I don't know since I don't have a smooth response. But, from what I've read, some people prefer implementing a house curve that increases the sub output as the frequency descends. This compensates for the loss of hearing sensitivity at lower frequencies. I hope to implement both a flat and a sloped curve this weekend and see which one I like better...
     
  16. Frank Carter

    Frank Carter Screenwriter

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    It will sound different than what you're used to. Movies or music that used to have tons of bass might not anymore. For example, my room had a wide 10dB hump centered around 45hz. When I listened to the Dino Fight in Jurassic Park III it sounded awesome but after eq'ing it lost some of it's bite(get it[​IMG]), however, I now can now hear the little nuances of the bass instead of just hearing one overpowering bass note. Movies like The Haunting sound better now, most of the bass is very low, in my system it's not being overpowered by the big hump I had at 45hz anymore and the low bass is just wicked. Basically what you're doing is going from what your room was making the sub sound like to what it actually should sound like.
     

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