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Sub Bottoming Out?

Discussion in 'Speakers' started by Larry Marq, Apr 1, 2003.

  1. Larry Marq

    Larry Marq Extra

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    I've heard mention on this board of subs "bottoming out". I have a SVS 20-39pci. What are signs it's being pushed too hard? Does the speaker actually extend to the point of hitting the base plate, or does it refer to just driving it to beyond maximum extension. Is it audible? I've been messing with different listening levels, even ref for a bit on Star Wars I&II. It seems to be fine except for my wife being really pissed. Just don't want to jack it up...
    Thanks, Larry
     
  2. MingL

    MingL Stunt Coordinator

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    I keep a few levels of checks that I listen out for signs of pushing it too hard....

    In their order:

    1) The cone excursion travels in & out so much its scary to see it like that.

    2) The bass sounds different at high volumes than at low volumes (eg, it starts to "fart" occasionally at louder levels, where it never did at low levels)

    3) Theres a distinct sound when it does bottom out. Distinct sound of metal stops within the driver hitting against each other. Ita a bone chilling sound, so best not to push it this far......
     
  3. Ryan-Stone

    Ryan-Stone Stunt Coordinator

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    I think i bottomed out my JBL PB12 once. I had just bought the new star wars episode 2 DVD. so i put it in and i didnt relize the volume was at 15 dbs higher than what i keep it at for movies. I went into the kitchen to get some ice cream while the yellow words part was going on. I took to long getting my food and the movie had started. all of the sudden i heard this weird and extremely loud sound. at first i thought the bass knocked something off a shelf and broke, but then i relized it was just the sub. so i turned it down to my regular volume and went back to see what it was. i was that part where that space ship flies by. thankfully there didnt seem to be any damage done. it was kind of scary though
     
  4. JakeMcM

    JakeMcM Stunt Coordinator

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    so its definently distinct when it does bottom out?
     
  5. Brett DiMichele

    Brett DiMichele Producer

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    When a sub bottoms out, the Voice Coil and Former (one unit)
    strike the Backing Plate/T-Yoke. When this happens you will
    hear a very loud and very distinct *Klack* sound.

    Repeated bottoming can mushroom the Voice Coil Former and
    in turn can warp the Voice Coil. When this happens the Voice
    Coil will begin to rub the inside of the Motor Structure
    (The Magnetic Gap) and you will hear a "scratchy" sound
    that won't go away. As time goes on the scratching of the
    Voice Coil against the Magnetic Gap will wear away the thin
    Laquer Shelac coating on the Voice Coil and when this takes
    place there will be a dead short and *Poof* your Sub
    will go up in smoke.

    Not good...

    Capiche?
     
  6. Larry Marq

    Larry Marq Extra

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    Comprende..
    Thanks, Larry
     
  7. Larry Marq

    Larry Marq Extra

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    Turns out it IS bottoming out...started a new thread...
     

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