Boomy ported 340L Tempest sonotube, similar to Ron's problem

Discussion in 'Archived Threads 2001-2004' started by Scott Parker, Apr 18, 2002.

  1. Scott Parker

    Scott Parker Agent

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    I finally finished my first DIY project, I'm in the process of covering it with fleckstone, I've already used like 7 cans of it, gets pretty expensive. I put like a 1/4 inch of polybatting around the sides but the glue didn't hold to good so now its just kinda laying in there. I'm getting pretty much was Ron was getting, a boomy, overhanging sound. My frequency response is fairly flat +/- 6 db. Would guys recommend stuffing it with say 8 lbs. of polyfill even though its ported. Its a 4' 24" (340L) sonotube. I guess that would lower the tuning wouldn't it, right now its tuned around 16hz. If all else fails I could plug the port. Is it true the bigger the sealed enclosure the tighter the sound should be? After seeing how much Ron was satisfied with his after the poly-fill it kinda made me jealous [​IMG].
     
  2. James W. Johnson

    James W. Johnson Screenwriter

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    I would say you either have a bad subwoofer placement or are crossing it too high..a bottom dweller like that should be crossed at 60Hz or less IMO and does not require corner loading.

    The first thing I would do is move the sub to a different location and go from there.
     
  3. James W. Johnson

    James W. Johnson Screenwriter

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    One more thing is make sure the sub is calibrated..an efficient sub like that does'nt need much power. It can sound overbearing quite easily if its too loud.
     
  4. ThomasW

    ThomasW Cinematographer

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    Scott

    Like Ron you need a lot more poly. If you're using the poly batting, it can be stapled to the top endcap, and draped down the sides of the tube. The loose fill poly is very difficult to attach to anything inside the tube.

    Don't be concerned about there being any significant changes in the tuning with the added poly.
     
  5. Ron-P

    Ron-P Producer

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    If it is anything like my problem Scott, it is a lack of poly-fill. I bought 80oz of the loose poly, packed it in and then placed a piece of the rolled poly over that then inserted the driver. That was added to the 24oz I already had in.
    It is well worth the small investment to see if it solves your problem like it did for me. Let us know.
    Peace Out~[​IMG]
     
  6. Mark Seaton

    Mark Seaton Supporting Actor

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    Hi Scott,

    One other aspect I'm curious about is the air space you have between the Tempest and the floor? You say your response is +/- 6dB. While hardly un-expected for an in-room response, where those variations show up could easily point to where your boomy characteristic comes from. Corner placement will generally allow for the greatest output, but you could also try placing the sub at either 1/2 point of the room's dimension for comparison. While it certainly depends on the dimensions of the room and where the listening location is, I often try the 1/2 point of the shorter dimension in the room first.
     
  7. Scott Parker

    Scott Parker Agent

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    I have about 4" between the tempest and the floor. I've tried various positions in the room but either way the response varies greatly as you walk around the room. Its a bonus room above the garage so the ceiling is not level all the way across, it slopes down from 8' to about 6' on both the left and right sides. Its about a 20' by 20' room with a good bit of stuff in it. But pretty much wherever you put it, it still has the overhang in the bass notes. It does have a good deal of output as the pod race shakes about everything in the room [​IMG]. I also have a Dharman and the Dharman doesn't appear to be as boomy. I was wondering if this was because of its smaller size. But you guys are saying it should get "tighter" as the enclosure size gets bigger right? So it seems to me like somethings wrong. I'll try the poly-fill tomorrow and let you guys know, thanx
     

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