Help! Subwoofer barely audible in new room.

Discussion in 'Archived Threads 2001-2004' started by EricHM, Mar 18, 2003.

  1. EricHM

    EricHM Agent

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    So a few months ago I built a subwoofer using a partsexpress Titanic mkII 12" in about 5 cubic feet tuned to 23 hz or so and a 250w PE amp.

    When I first hooked this sub up at my parents' house after I built it, I was blown away. The walls were shaking, and I could really feel the bass hit me in the chest. The bass was just dominating, very thick and very deep.

    Then it came time to move this bad boy into my dorm room......and the results were very disappointing. Despite my room being smaller than the room I tested it in at my parents house, the bass output has almost completely disappeared. I've tried moving the sub all over the place, into every corner, along every wall, right smack in the middle of the room....you name it I've tried it.

    No matter what, the level of output remained extremely lackluster. Right now I have the sub sitting in a corner of the room behind the TV, and from where I sit (pretty much in the middle of the room) I get almost no bass.

    However, if I move to the very, very opposite end of the room, against the back wall, at the furthest possible point away from the sub I get a decent amount of bass. Still, even this spot isn't even close to as good as it was in the original room.

    My dorm room is 17' long, 8' wide, and 10' tall. The floors are hardwood and all the walls and the celing are a hard plaster type material. The sub is downfiring and the port is side firing. Is there anything at all I can do to get my bass back?!?!?!?!

    PS: here are some pics of the sub

    http://www.geocities.com/erichmassey/woofbot.jpg
    http://www.geocities.com/erichmassey/wooffront.jpg
    http://www.geocities.com/erichmassey/woofback.jpg

    Thanks for your time,

    Eric
     
  2. Rob Formica

    Rob Formica Stunt Coordinator

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    Have you checked the polarity of you connections? The symptoms seem quite similar...
     
  3. EricHM

    EricHM Agent

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    Yeah, the amp even has a phase control, I've tried it at 0 degrees, 90 degrees, and 180 degrees and it sounds pretty much the same to me at all the positions. I just leave it on 0 for the most part.

    The connections between the amp and the speaker haven't changed since I first built the thing, since the amp is mounted on the back of tne enclosure.
     
  4. ColinM

    ColinM Cinematographer

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    Can you force the speaker to play loudly? as in feeding it a deep tone and look for cone movement?

    Perhaps there is a fault in the amp due to the move or something. If you can't force it, there must be a fundamental problem with a component.
     
  5. EricHM

    EricHM Agent

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    Oh yeah, I can definitely see the cone moving, it's excursing quite a bit there just isn't that much sound being produced. It's almost like the bass is being cancelled out or something.....I was very careful during the move so I doubt anything was damaged but I suppose it's a possibility.

    Also, I hear things in the room rattling around during deep bass tones (especially things close to the sub), but just don't hear that much bass. I can also "feel the vibrations" from my chair, it just doesn't "sound" loud. The whole phenomenon is really quite strange......
     
  6. Rob Formica

    Rob Formica Stunt Coordinator

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    try plugging just the subwoofer, and then one channel at the time, and see if you get less bass at some point?

    If you hear no bass with just the sub playing, is your cross-over point to low and you are maybe loosing out the mid-bass punch you had ?
     
  7. ColinM

    ColinM Cinematographer

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    I'm sure you know that bass below, say, 23Hz is almost inaudible...

    Beastie Boys' "Brass Monkey" has good 50Hz stuff - you should hear that pretty good.

    But, the thing worked like a charm before, and now - nothing? Strange.

    Good Luck!
     
  8. Brian Foley

    Brian Foley Agent

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    My first guess is that your receiver is not set up properly. I know on my Pioneer there's a max subwoofer level setting in the main menu, and until you set that properly, the subwoofer output is very low. Try setting your main speakers to large and plugging one of your speaker cables into the sub amp's speaker-level inputs. If the bass is back, then it's a receiver setting. If it's still real low, then it's a setting on the sub amp, probably the low filter setting. Actually, since that's the easiest thing to change, try changing it first. The more I think about it, that's the more likely culprit.
     
  9. you wouldn't by chance have a "cube-ish" room and have your listening position in the middle would you?

    sounds to me like you are sitting in a huge null. The reason other things vibrate is that the walls are at a mode, not a null.

    try modeling your setup with the RRC and see what you get [​IMG]

    http://www.pvconsultants.com/audio/frdgroup.htm
     
  10. EricHM

    EricHM Agent

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    It's not producing "nothing" it's just nowhere near it was before; I would estimate that if I stand in the very back of the room against the wall it's at about 2/3 the level it was in the original room, but just about anywhere else in the room it's at 1/3 or less what it was in the first room. I'm inclined to believe the acoustics in this room are simply terrible for bass (too many hard surfaces) and was curious if anyone had any placement tricks.

    I am certain that the speaker is hooked up the same way it was in the first room....crossover is fine, set to about 60-70 hz. There is no high pass filter, and I'm aware than anything below 25hz is getting into the nearly inaudible range.
     
  11. EricHM

    EricHM Agent

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    Regarding the reciever, I'm using a 2 channel Denon right now. I'm only running stereo speakers but the Reciever has a summed mono subwoofer preout which I'm feeding into the Right side input on the amplifier. I don't think it matters if I plug the sub pre out into the left or right input since it's a mono amp anyway.

    The reciever itself doesn't have any subwoofer signal processing features or crossovers (Denon DRA-395 is the model #), only basic treble and bass tone controls which I usually leave flat.

    Anthony....as a matter of fact my room is somewhat cubish and I do usually sit right in the middle of it.

    The dimensions of the room are 17 feet long, 8 feet wide, and 10 feet tall. I'll see what I can figure out from the link you gave, thanks!
     
  12. the best placement "trick" is to put the sub exactly where the listeners head is, and then crawl around the room. THe location where the bass sounds the best is where you want to put the sub.
     
  13. EricHM

    EricHM Agent

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    Yeah, I've heard about that method and I tried putting the sub in the same place as my chair then walking around to see where it sounded best, but I couldn't find any sweet spots. Even the back wall sweet spot which is there with the sub in the corner disappeared when I put the subwoofer where my chair usually sits.

    Then again, I suppose the sub wasn't exactly where my head usually is since I'm about 6'1" and the sub was only 4" off the floor.
     
  14. Jeffrey Stanton

    Jeffrey Stanton Stunt Coordinator

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    FWIW 17' X 8' X 10' is not cubish (not even close)...[​IMG]
     
  15. Greg Yeatts

    Greg Yeatts Second Unit

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    Try using a Y-connector at your sub-amps input. This shouldn't make a difference, but in my case, it did.
     
  16. Lee Carbray

    Lee Carbray Second Unit

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    I have read something like this before from a member here. He had his sub in a dorm room and could never get the base to sound very loud. Yet after hours of testing and playing around the student in the room below his finally came up because the base in her room from his sub was unbearable. I do not think he ever found a solution to his problem but it sounds like your the room has acoustics similar to that.
     
  17. EricHM

    EricHM Agent

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    sorry, maybe I should've said rectangular prisimish, mr geometry. [​IMG]
     
  18. Garrett Lundy

    Garrett Lundy Producer

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  19. TimForman

    TimForman Supporting Actor

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    It's starting to sound like the room dimensions don't support long sound waves well. I've had similar experiences where there is more bass outside the room than inside. A possible solution would be to get a BFD and a SPL meter and try to compensate for the room acoustics.
     
  20. ColinM

    ColinM Cinematographer

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