26 Hz rumble - from standing waves?

Discussion in 'Home Theater Projects' started by Bhavesh P, Sep 23, 2003.

  1. Bhavesh P

    Bhavesh P Extra

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    Recently I sold a 10" Eclipse 88000 (10" aluminum cone subwoofer from car-audio) to buy speakers and a cheaper subwoofer (elemental designs e10k) to go in a 0.5 cubic foot sealed box (recommended). After the initial week break-in period, I gave the sub various tests in test tones, techno/dance, and rock music and I was quite disappointed. It sounded ok (smooth bass, no "fart", deep sound) at low volumes but with gain it just bottomed out violently and "farted" with every sound.

    With no time, money, or alternative, I brought the e10k with me to school and placed it under my bed facing the wall, near a corner. I crossed it over a second time after the computer output, through a passive eq, before it got to the amp (crossed over at 80Hz) with I kept the gain slightly below 1/2 (partsexpress plate amp).

    But now when I play "get low" (by little john) or run a sweep from 0-120Hz, I get this low (and loud) rumble at 26Hz before the sub is even close to bottoming out.

    Is it from the acoustics of the room, causing a standing wave? It's a bigger room, but I also have 2 crossovers to cut out upper frequencies with slightly higher gain. The response isn't flat, but I would like to make it so.
     
  2. Neil Joseph

    Neil Joseph Lead Actor

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    Moved to DIY/Advanced area.

    What is the enclosure tuned to?
     
  3. Dave Poehlman

    Dave Poehlman Producer

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    26Hz is a pretty long wavelength to get a standing wave out of (like 43.5'). What are the room dimensions? It's possible, I suppose, if you have a room dimension where the wave would be halved or quartered. It's under your bed, so, I would bet the resonance isn't between the floor and ceiling.

    What are the walls made of? You also may be hearing some sort of resonance out of drywall or flooring itself.

    Sound is wierd.
     
  4. Wayne A. Pflughaupt

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    Bhavesh,

    You should ditch the idea of using car subs for a home theater application, especially small ones in tiny enclosures – that is, unless you have a home theater set up in a space the size of a car interior. As you have already seen, they don’t work well once you get them in a larger space.

    Regards,
    Wayne A. Pflughaupt
     
  5. Anthony_I

    Anthony_I Stunt Coordinator

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    My phoenix gold octane r12d works great as a music sub and also as a HT sub for movies and EXPLETIVE DELETED.
    Except PG reccomends a 0.9Ft^3 box for bigger bass and less accuracy and a 1.2Ft^3 box for more accuracy at a slight loss of bass.
    However i put it in a 3Ft^3 box and it sounds DAMN good.... even without proper speakers yet (im using EXPLETIVE DELETED mini stereo systems "surrounds" as my L/R... EXPLETIVE DELETED but all i got for now) and man..... what a great sound.
    Though it could probably be improved im quite happy as it is right now.

    when i get my system all done, then i will worry about calibrating EXPLETIVE DELETED.

    WARNING!

    Anthony,

    As others have pointed out, this is not the place for that type of language. There are other venues on the web more suited to that. Please respect the others here or the next thing to be deleted will not be an expletive.

    -The HTF Administration
     
  6. Brian Bunge

    Brian Bunge Producer

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    Anthony,

    Do you kiss your mother with that mouth?[​IMG]

    This ain't the car audio forums.
     
  7. Scott Simonian

    Scott Simonian Screenwriter

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    Holy cow! What did I miss?

    Bhavesh, maybe you should look into building your own HT sub. There are many a drivers out there that are cheap and have top-notch performance.

    Try here. I started my DIY hobby with this company. They have great designs based off of their drivers.
     
  8. Anthony_I

    Anthony_I Stunt Coordinator

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    Oh, I'm sorry, I honestly didnt realize what i was typing, [​IMG] nor did i mean to create any friction.
     
  9. John_MackieBass

    John_MackieBass Stunt Coordinator

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    Sealed boxes with car audio subs in a home environment (especially a 10") are at a severe disavantage over ported boxes. Car audio companies plan for cabin gain with their drivers, which really helps low end extension. What you are probably hearing is motor noise from overexursion. You CAN have motor noise and not bottom the sub out. Other things to check for are leaks in the box, and tinsel leads slapping the cone.

    You can try different locations around the room to get better response. I always found corner loading kitty corner from your listening position works best...but every room is different.

    Your best option is to go down to the lumber yard and make a ported box for it. In a room, with a ported box you'd probably get more than twice as loud with that sub. It doesn't have to be one of these 20cube sonotube monsters or anything...when I was strapped for cash I whipped together a VERY small ~1.25cuft ported box tuned to about 30hz for an old Cadence Ultra-Z...ran it off my mackie 1400i (at 500rms [​IMG] ) and IT THUMPED! Granted it didnt hit amazing 20hz notes, but regardless...it was VERY loud for a little sub in a LARGE room!
     
  10. Anthony_I

    Anthony_I Stunt Coordinator

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    Would this same idea work for a 12" car audio sub?
    Its supposed to be in a 1.2Ft^3 vented box, or a 0.9Ft^3 box for sealed. Right now its in a 3.0Ft^3 box and it sounds great, but im left wondering how a smaller box might sound or even a vented smaller box.
    Also there are two different boxe sizes listed for vented and sealed.
    Musical and SPL. SPL gives better bass, and musical is better at reproducing the way the music sounds.
    the 3.0Ft^3 box was suggested by a member here.

    sorry i dont mean to hijack this thread but i thought id ask here instead of starting a new thread.
     
  11. John_MackieBass

    John_MackieBass Stunt Coordinator

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    anthony...the box design depends completely on the driver and the goals you wish to accomplish with it. If you want more SPL, you'll want to go with a ported or Bandpass box (usually at the cost of sound quality)
     

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