Is it possible to bottom out a powered tower?

Discussion in 'Archived Threads 2001-2004' started by Bob_A, Oct 23, 2001.

  1. Bob_A

    Bob_A Supporting Actor

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    Just wondering if this is possible...particularly with powered towers which have side firing woofs.
    I do not think it is possible to bottom out my 2000TL...
     
  2. Jon_R

    Jon_R Stunt Coordinator

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    It is possible to bottom out anything. Some are more difficult than others, but it is definitely possible. A powered tower is often not the best subwoofer because lots of money was spent in other areas. Don't get me wrong, they can act as very good subs, but they have limitations. That being said I believe that you could bottom out a powered tower.
    Someone correct me if I am wrong, isn't "bottoming out" when the excursion (be it inward or outward) of the cone exceeds what the suspension will allow? The noise is then the voicecoil hitting something right?
    I sure drifted off the technical aspect by the end of that one. [​IMG]
    Just a thought,
    Jon
     
  3. Dennis Kindig

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    I am repairing a Def Tech sub amp right now with a fried resistor on the board. I believe that this is a 2000TL as well.
    I was researching the amplifier unit and found that it is a Sanyo inline package that produces 200W. I would say that it depends on the quality of the woofer itself as to whether it would bottom out. My Shiva will take 600W. Not sure what the cone in the Def Tech is rated for, but 200W is pretty hefty.
    Dennis
     
  4. Bob_A

    Bob_A Supporting Actor

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    The only reason I think my powered towers do not bottom out is that I have cranked Episode I The Phantom Menace and have not had any problems. It is possible that there is some electronic limiter...I can't say for sure.
    But for other powered towers...who knows whether they can bottom out?
    I realize that adding some quality external subs will be particularly beneficial for me below, say, 30 Hz...but I feel that there are some benefits to having a well designed powered tower (I discussed this in a thread a couple weeks ago). I was also suprised that I was getting pretty good shake with Episode I on the THX intro and pod race scene...I was under the impression that this bass was below 25 Hz (I could be wrong though).
    Dennis, the 2000TL's supposedly have a built in 500 watt amp...of course this spec by itself doesn't mean much. Certainly the speaker you are fixing did not bottom out, correct? Fortunately for me, I have cranked the heck out of these DT's (being driven only by a receiver and in a huge room), and they have never strained at any level.
     
  5. Greg_R

    Greg_R Screenwriter

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    I doubt you could bottom them out... most commercial subs have limiters to prevent this (which unfortunately limit dynamic headroom as well). The powered section of your 2000TLs probably have a similar circuit. SVS and Aerial are examples of two companies that don't have limiter circuitry on their subs...
    Greg
     
  6. Jeremy Hegna

    Jeremy Hegna Supporting Actor

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    "It is possible that there is some electronic limiter...I can't say for sure."
    That is exactly why you haven't heard them bottom out. The circuitry will not allow bass below a certain frequency to be produced by your driver....just gets eliminated.
    Most commercial subs have the same limiters on them, less concern about replacing blown drivers under warranty [​IMG]
    Jeremy
     
  7. Graeme Shiomi

    Graeme Shiomi Stunt Coordinator

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  8. Tom Vodhanel

    Tom Vodhanel Cinematographer

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  9. Bob_A

    Bob_A Supporting Actor

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    Graeme, I was a little surprised because my towers supposedly roll off below 25-30Hz...interestingly, I uncoiled the POWER cords for each powered tower bass section, and now I am getting slightly fuller bass than I was getting before. I know it sounds strange...but for me, cleaning up wiring (including cables) has made a significant improvement in my system.
    Edit: Thanks for the clarification guys!
    [Edited last by Bob_A on October 23, 2001 at 08:55 PM]
     
  10. Hubert

    Hubert Second Unit

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    Tom makes a good point. However, I've done the same thing as you Bob with my BP3000TLs. I've avsolutely cranked them to ungodly levels on TPM and not once did I ever even hear them strain, much less bottom out. For what I know about the speakers, they do have a limiter that doesn't necessarily stop it from going real low. My understanding of what it does is that once the sub reaches a certain level, the limiter just keeps it from getting so loud that it distorts and bottoms. The BP3000s can certainly produce a 20Hz signal, however the limiters keeps it from being overdriven.
    However, unlike you, I have my BP3000s filtered at 30Hz. So they don't produce anything lower than that. The Velodyne HGS-18 handles LFE and all bass info below that.
     

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