Does this trick for placing subs work?

Discussion in 'Archived Threads 2001-2004' started by Geoff S, Nov 1, 2002.

  1. Geoff S

    Geoff S Stunt Coordinator

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    First off, Wow, I've been out of the game for like 2 months or so, this is the first post I've done in a while...

    As to the question at hand: i heard a long time ago that there was a way to place a subwoofer so that you get the best bass response at the listening position. The trick is, to put your sub right at the listening position, then walk around the room till you hit the spot that you feel the bass the strongest; that spot is where you will place your sub to get the best response while in your favorite seat.

    So does this work? Or is it hogwash? To me it doesn't seem right since there will be reversed acoustic properties, and the size, dimensions, and shape of the room are the main factors. In the end isn't it just best to put your sub in a corner and get good response that way?
     
  2. Geoff L

    Geoff L Screenwriter

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    Hi Geoff

    Yes this approach can work. Of course the sub will be setting on the floor so getting lower to the ground is important when crawling around and listening for bass output while it's in your listening chair.. Tweeking and measuring with a freq disc and spl meter afterwords might find you moving the sub inches or feet one way or the other.

    Corner loading is going to excite the most modes but dose not always produce the best results. All rooms are different especialy if they have openings to other areas, weird funiture layouts, and the shape & size of the room. What works for one rooom, do not assume it will work best for another.

    Experimentation is usually your best approach. Corner loading will provide the most free gain but may not produce the flatest response. Walking or crawling around while the sub is in your listening chair and selecting the point at which you favor the sound can work.
    Again it may not not measure the flatest their either.

    But in the end you can measure what you finally came up with for placement to know what actually is going on with the subs output.

    It dosen't matter what anyone else thinks of the bass but you! Your the one whos going to enjoy it. So even if it dose'nt measure perfectly flat, ( rarely if ever dose this happen) your the one thats needs to be happy.

    So yes it dose work, not the most sientific approach, but works non the less...

    Regards
    Geoff L
     
  3. Ned

    Ned Supporting Actor

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    I don't find that trick effective. What do you listen for when checking various spots? Your ears are not good at evaluating test tones and just using music or a movie is too variable to be accurate.
     
  4. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    That's why the subwoofer plays white/pink noise so you can evaluate the position that simply produces the most bass. I think ppl are basically listening or measuring for the most output. The sound difference people hear when doing this is probably the effects of standing waves within the room.

    When you use this method you will find the position that gives you the most SPL which to some people may be the best position.

    But if you're looking for a smooth frequency response then you may not want to corner load it but instead position the subwoofer to aid in cancellation of standing waves.

    I think what's common is a corner loaded sub that gives maximum SPL, and then the use of electronic equalization to adjust the freq. response. So I guess I could say: using the method described above might actually give you a bad freq. responses, but give you the most bass.
     
  5. Greg_R

    Greg_R Screenwriter

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    Use the trick, but use a SPL meter and find the area of the room that gives you the flattest response. Put your sub in that location (unless you have an EQ).
     
  6. steve nn

    steve nn Cinematographer

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    I have herd of this suggestion but to me it seems kind of of the wall. How can I place a couple of 80 pound subs on the couch? I did use the meter to confirm what I perceived to be the best location and used the meter to confirm other locations were not as good or efficient as the one I chose. I can see how this can and will work but I think it "has its limitations".--Well that's what Eastwood told me.[​IMG]
     
  7. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    It would be nice to run sweeps and use a measuring device and keep track of data.

    However, some ppl don't have the equiptment so I thought listening for the loudest perceived pink noise could be useful in finding the output efficient location.

    Sure, even the best position you may find will still have dips/peaks in the response. What people then do is try and fix the problem with acoustic treatments or equalization.

    Some advice for those wondering about Equalization:

    1. Dips in the response should not be filled. It is laughable how a 9db increase needs almost 10 times the acoustic power and then you'd have tons of bass in other parts of the room. Do not increase volume at dips with equalization!

    2. What you need is parametric equalization (filters) with the proper measuring equiptment. (High resolution equiptment of 1/10 octave or better). A very vague 1/3 octave graph can easily miss the details that will still cause bass irregularities.

    3. A common graphic equalizer may not solve bass problems even if you could see where they are on a graph. They are simply not accurate enough to solve the problem.
     
  8. Thomas J. Coyle III

    Thomas J. Coyle III Stunt Coordinator

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    Geoff
    Once you get your subwoofer placed, and yes you can put the subwoofer in your listening position and move the measurement mike around, then you might want to consider the Behringer BFD to get a reasonably smooth roll-off down to 20Hz. You might like to try out the procedure on Sonny Parker's website: www.snapbug.ws/bfd.htm.
    Regards,
    TCIII
     

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