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bottoming out??!

Discussion in 'Subwoofers' started by andyblack18, Feb 22, 2005.

  1. andyblack18

    andyblack18
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    somebody told me my subwoofers were "bottoming out" the other day because they kept popping when at high volume. an iv no idea what it means??!
    sumbody help me!!

    ANDY
     
  2. mps

    mps
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    Is the placement or the firing port too close to a wall?

    cheers.
     
  3. SOUNDSTYLE

    SOUNDSTYLE
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    I had the same problem with my REL Q100E. The amp inside your subwoofer is not powerful enough at the volume you want it.
    I sold the REL and got a Velodyne CHT15 with a 300 watt amp inside.
    No problems now. :clap:
    What subwoofer do you have by the way?
     
  4. eviljohn2

    eviljohn2
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    Bottoming out means that the driver is reaching the endstops. That is to say, it can't travel any further each direction.
     
  5. micb3rd

    micb3rd
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    Not correct that is clipping not bottoming out.

    A driver runs out of mechanical excursion when it travels past its x-max limits the motor structure can slam into the driver backplate, this creats a loud crack/clack sound. As this happens many times a seccond you get repeated clattering sound.

    All drivers have excursion limits, these limits are govened by the build of the driver but also the type and size of enlcosure used will control excursion.

    The solution, if you play the subwoofer to the limits and bottom your drivers you need to get better louder subwoofers.
     
  6. gavp

    gavp
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    i have noticed this problem, for example watched The Punisher the other day, sounded excellent no problems, then put on Hellboy immediatly after and the sub starts popping and has me leaping off my chair to fiddle around with the controls (at the back of course) :suicide:
    I currently have a AE evo sub, which as much as its ok has made me realise if ya want somethin good ye have to pay for it, am so tempted by the SVS's but something like the Quad L with A) remote control, no more leaping! and B) advanced protection which doesn't allow too much current to cause said 'popping/clipping etc etc looks like it may swing it over the americans :uk:
     
  7. Ettepet

    Ettepet
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    I was playing Sky Captain and the World of Tomorrow the other day, and with my callibrated setup the PB12-Ultra/2 was not all that far from hitting the base plate during some instances. That was at 12dB below reference! :eek:
     
  8. Mroizouk

    Mroizouk
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  9. Ettepet

    Ettepet
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    Possibly. I had my hand underneath and several times I felt my hand getting 'caught' between woofer and base plate, so there was another centimeter or so left.
     
  10. Nimby

    Nimby
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    Only "another centimetre or so" ?

    Some subs don't have a whole centimetre of cone movement to their name. :blush:

    If I was really clever I could tell you what effect "just another" centimetre of cone movement means in real output terms. :lesson:

    But I'm not, so I won't. :clown:

    Nimby :D
     
  11. bbasra

    bbasra
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    Whats happens if the firing port is too close to the wall. :confused:

    Mine is quite close?
     
  12. Nimby

    Nimby
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    A number of possible things could happen.

    Resistance to port flow may affect the deepest frequency output. Either by spreading the frequency range coming out of the port. Or reducing it by blocking port flow.

    Or you might get an increased baffle effect from the proximity to the wall.
    Which might increase low frequency output.

    Or you could just move the sub slightly to give the port a chance to do its best. Which is what the designer intended when he tested the port length and size against enclosure volume. :)

    Nimby
     
  13. Diamond

    Diamond
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    PB10 is almost impossible to bottom out, at least many have reported so. The amp seems to limit the output first, so a safe listening is guaranteed. We have verified this also with "pretty astounding" levels. :eek: :D
     
  14. micb3rd

    micb3rd
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    Base plate?

    Do you mean base plate of the subwoofer enclosure, because that is something very different to "backplate".

    When I said backplate in my post about bottoming, I was talking about the rear of the driver inbetween the magnet/s and the motor assembly, with the spider and basket metal you can't get you hand near the backplate of a speaker driver.
     
  15. Ettepet

    Ettepet
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    As far as I am aware the PB12-Ultra/2 has only one base plate, with little room left to mistake it for anything else.
     
  16. micb3rd

    micb3rd
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    Re-read, my posts when talking about bomming a driver, it is the *backplate* of the driver not the base of the enclosure.

    You can bottom a driver freeair with no enclosure attached to it at all, in fact this is the quickest way to bottom a driver as there is not enclosure proving excursion protection.
     
  17. Ettepet

    Ettepet
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    Again, I was talking about Base plate. I never had my PB12-Ultra/2 hit its backplate either, no clack/clank or such. Might have run into that with my PB12-Plus/2 a bit once, but I'm not sure.
    --
    Oh man, do I love the sound of my setup, after solving the bad accoustics of my (sonically hard) concrete living room with accoustic tiles: JMJ's Aero, The Incredibles, Jurassic Lunch, Techno sound-sweeps, etc. etc. Sound dies out so quickly (especially higher frequencies) I sometimes don't believe my ears....

    Sorry about going off-topic like that, even after 2 months it brings a broad smile on my face and my mind wanders off a bit. Maybe something for a future topic on accoustics and subs. :)
     

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