Sub Placement and impact question

Discussion in 'Speakers & Subwoofers' started by Steve Lucas, Nov 18, 2003.

  1. Steve Lucas

    Steve Lucas Stunt Coordinator

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    I finally got around to finding the best spot in my room for my sub (flattest response). However, now that I've moved it and recalibrated the audio, I seem to have lost a a lot of impact. It was corner loaded before, and now it is midway along a wall. I know that the corner reinforced the bass output, but wouldn't calibration bring it back where it should be? (i.e. a higher volume setting, but still the same overall volume as before). Should I just crank it up some more to get the impact I'm used to and calibration be damned? Or is it possible I am accustomed to hearing the uneven response i was getting in the old location and just don't like a flat response?

    Anybody been through this?

    Thanks,
    Steve
     
  2. Wayne A. Pflughaupt

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    My thoughts: Put it back in the corner and get your flat response with a parametric equalizer. You’ll find it will blow away what you’re getting with mid-wall performance.

    Do a search on “BFD,” Behringer Feedback Destroyer,” or “parametric” and you’ll get enough reading material to keep you busy for days.


    Before BFD

    [​IMG]


    After BFD
    [​IMG]


    Regards,
    Wayne A. Pflughaupt
     
  3. Ned

    Ned Supporting Actor

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    Steve-

    How did you conclude that the midwall position was "flattest"?


    Wayne-

    That example shows the 80-89hz range increasing 15db in the after. Was that achieved purely by equalization? (hella boosting)
     
  4. Wayne A. Pflughaupt

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    Boost, cut – it’s all academic in the end.

    In this particular case the user was pretty determined to get that picture-perfect line, and he burned 11 filters to get it. You can follow the thread here. The filters used in this curve are detailed in post #16 – the biggest boost was +8dB.

    Regards,
    Wayne A. Pflughaupt
     
  5. Steve Lucas

    Steve Lucas Stunt Coordinator

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    I used frequency sweeps and a SPL meter, standing in different locations around the room with the sub positioned in my primary listening position.
    I had been considering a parametric eq, but hadn't priced them as yet. Any idea how much a decent one costs? How much for a BFD?

    Thanks,
    Steve
     
  6. Steve Lucas

    Steve Lucas Stunt Coordinator

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    Wayne,
    I looked up the BFD. As I understand it's use, it will locate potential feedback frequencies and pull them down using the parametric eq. How does it flatten the subs response if it has large dips in the curve as well as, or instead of peaks? Do you have to do it manually? If so, what's the advantage of having the BFD? Why not just use a regular parametric eq?

    Steve
     
  7. Wayne A. Pflughaupt

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    Sorry to leave you hanging, Steve.

    The BFD’s automatic feedback capabilities are for pro-audio purposes only - it has no use to us. What HT people buy the BFD for is its parametric capabilities. It’s very popular because it’s dirt-cheap and it has twice as many filters as an analog parametric.

    Yes, the filters have to be set manually, and used that way you can do both boosts and cuts. You can find more information about how it works and what you need to set it up at Sonnie Parker’s BFD Comprehensive Set Up Guide. Everyone agrees the manual is a challenge, so if you get one you’ll be spending a lot of time there.

    You can also do a search for "BFD," "Behringer" or "parametric" this Forum and the DIY forum and you’ll get enough material to keep you busy for days.

    Regards,
    Wayne A. Pflughaupt
     
  8. Steve Lucas

    Steve Lucas Stunt Coordinator

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    Thanks Wayne.
    I did some looking around and I have a good friend who is a Rane dealer. I think I'm going to get 2 Rane THX-44's. He will sell them to me at his price, which is about half of list.
    If you don't mind, look it up and tell me what you think of it for my application. (I'm running 6.1 surround and intend to ad a second sub soon).

    Steve
     
  9. Wayne A. Pflughaupt

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    The 44 is great if you’re looking to EQ your mains – I guess you know you’ll have to have pre-outs and main-ins on your receiver, right? Most receivers don’t have main-ins on all channels, which means you’ll be using outboard amps for all channels that don’t.

    As far as using the 44 for the subs, it only has two parametric filters, and that’s never enough. I’ve followed dozens of sub EQ threads here over the years and you hardly ever see anyone getting the job done with less than 4 filters.

    Still, if you get two 44s you could daisy-chain the sub EQs and double the available filters – that may be enough to get you by. But if not...

    Also, the maximum boost/cut available is only 6dB. That probably won’t cut it; it’s very common to need at least a one or two filters with much more adjustment – up to 12dB, occasionally even more.

    Bottom line, I know the BFD is a low-end piece of gear, but it’s really hard to beat it for EQing subs.

    Forgot to mention in my last post, a couple more advantages of the BFD over a regular parametric:

    Since it’s digital, the frequency centers can be set with pinpoint accuracy. With an analog parametric, nailing the target center frequency is much more difficult.

    Also, the BFD has no knobs that can be accidentally turned and mess up your “hard earned” settings.

    Anyway, those are my thoughts - worth exactly what it cost ya. [​IMG]

    Regards,
    Wayne A. Pflughaupt
     
  10. Steve Lucas

    Steve Lucas Stunt Coordinator

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    My amp does have pre-outs and in's for all channels, so that's not a problem. As for the number of filters, Judging from what I saw during freq sweeps, I have one dip around the crossover frequency and one more around 60H. From there it seems to rise pretty smoothly till the sweep stops at 20Hz. I think I can get it done with 2 or 4 filters. It's also been my experience in pro sound situations (live music) that very small adjustments are almost always enough, and prefered over large boost/cuts. I'm thinking that with my friend being a true pro (one of the most respected gospel studios in the country), and hs real time analyzer, wh should be able to tame the room without resorting to very large adjustments. Maybe I'm wrong, but if I am, since he's a friend, I caould always return the eq's and try again with something else.
    I'm all for saving money, but the concern I have with inexpensive eq/s is that the filters are usually sub par. I asked him about using the alesis 1/3 ocatve eq's, and he told me he wouldn't put one on a boom box. He said the filters are junk. He said Rane is probably the bottom of the quality that he carries that he would consider on my system. Since I can get them at a good price, I think I'll give them a try.
    Thanks for the advice. Itls nice to be able to bounce things off of someone. I may yet have to go with more filters or higher boodt/cut, but I'm going to try this first to see.

    Steve
     
  11. Gordon Groff

    Gordon Groff Second Unit

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    The Rane is a good unit. Getting it at cost is cool.

    What allows the BFD to be so inexpensive is that it's a DSP unit, so all filters are software-set in the digital domain. I would worry about the A/D and D/A for full-range high-end audio, but for sub EQ, it's a pretty cool solution IMO. Of course, who am I to talk. I have not set mine up yet. Too Lazy. Enjoying my system too much to take time to fool around w/it.
    (Before I get all the posts telling me I should get off my butt and do it, I know, I Know!) :b

    Gordon
     
  12. Wayne A. Pflughaupt

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    A few more things to consider, Steve.

     

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