Bag End's 18" driver... how can it hit 8 Hz? How to replicate it in DIY?

Discussion in 'Archived Threads 2001-2004' started by Javier_Huerta, Mar 8, 2003.

  1. Javier_Huerta

    Javier_Huerta Supporting Actor

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    It says it has an "ELF integrator".

    http://www.bagend.com/infrasub18.htm

    The sub itself has a 3 cu. ft volume with an 18" driver. What???

    Is the "ELF integrator" a simple parametric EQ? I'd think those 400W would not last very long when trying to reproduce an 8 hertz signal.
     
  2. Owen Bartley

    Owen Bartley Second Unit

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    I've always wondered about the Bag End Infrasub 18. A few years ago I saw it as the ultimate subwoofer (based solely on specs, as I have not ever heard one), but now that I've learned so much in DIY... I don't know how well it would hold up. I'd be very interested to hear from people who have experienced this sub.
     
  3. Dustin B

    Dustin B Producer

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    I forget the specifics, it's something to do with operating the driver below it's Fs for its entire bandwidth (which requires a bunch of EQ to compensate for the role off associated with opperating below Fs).

    Bottom line though is they aren't giving the whole story. Sure its flat to 8hz, but only at low output levels. When max output was tested its output below 30hz dropped off quickly. Down 5dB by 25hz and down greater than 15dB by 20hz. Was also only capable of averaging ~105dB from 25-63hz which means the cheapest SVS subs can beat it output wise.
     
  4. Shawn Solar

    Shawn Solar Supporting Actor

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    Look at the way they worded it. The amplifier is flat to 8hz. The really make no metion of the sub playing 8hz. Anyone that tried to play a 8hz tone through the sub would problably disapointed. One cuase they could not here it and secoundly any thing shaking in the room would be caused by 2nd or third order harmonic distortion. plus, just my guess the sub probably has some sort of protection on the driver or/and amp and won't play anything below 16hz or so. Again that is my guess. most DIY subs would be the same as the bang end. only a few subs(DIY) that I know of that could play that low 10hz belong to people that have a multiple woofer system(infinite baffle).
     
  5. ThomasW

    ThomasW Cinematographer

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    Actually it will play that low. But there's no software available with any info that low. So unless you like listening to test tones, the 8Hz output isn't all that useful.

    The issue with the BagEnds is that they will play quite low but they don't play really loud. (remember Hoffman's Iron law [​IMG] )

    For any real world use having a system with solid output to 15Hz should IMO be the goal.....

    I've measured 5Hz output on my big IB but it's of course inaudible. The house starts shaking with 16Hz notes (that appears to be the Fs of the house), so output lower than that is only adding to the house shake.
     
  6. Javier_Huerta

    Javier_Huerta Supporting Actor

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    5 Hz output... Did you measure this while using the Twelve Shivas Dancing?

    Now, *that's* a real subwoofer. [​IMG]
     
  7. Scott Simonian

    Scott Simonian Screenwriter

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    No kidding.

    [​IMG] [​IMG]
     
  8. ThomasW

    ThomasW Cinematographer

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  9. Dustin B

    Dustin B Producer

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    Any chance you'll ever do a Nousaine style max output measurement on your big IB Thomas? The little one too while you're at it [​IMG]
     
  10. Javier_Huerta

    Javier_Huerta Supporting Actor

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    Practically flat to 15 Hz. Wow!

    Thomas, did you use any kind of equalization? Were your measurements taken in-room, or at the manifold's exit?
     
  11. ThomasW

    ThomasW Cinematographer

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    Guys,

    The measurements above were nearfield (outlet of the manifold) with no parametric EQ. After dialing in some EQ it's ruler flat to just above 10Hz.

    Regarding max SLP testing, there's a 55 sq ft picture window in the room. I'd prefer not to replace it [​IMG]

    Computer modeling suggests ~130+db @ 20Hz. With a 'moderately' loud 16Hz test tone, the entire 2500 sq ft brick house will shake.[​IMG]
     
  12. Jack Gilvey

    Jack Gilvey Producer

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  13. RayJK

    RayJK Stunt Coordinator

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    Jeez Thomas, what did you use to get a 5hz tone? I have some test CDs that are good to 10hz and like you the 2500 sqft brick house starts to resonate about 15hz. Once I get the BFD in the system I expect to be flat to about 12-13hz.
     
  14. ThomasW

    ThomasW Cinematographer

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  15. Javier_Huerta

    Javier_Huerta Supporting Actor

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    Jack, thanks for the link! IT's quite an interesting article, though I'm convinced one could do the same with a paraemtric EQ: )
     
  16. Bill Fagal

    Bill Fagal Stunt Coordinator

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    For a low AND loud flavor of the ELF concept, check out Bag End's Bassault-R. Footprint may be an issue though...

    Bill
     
  17. Jack Gilvey

    Jack Gilvey Producer

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    Cool...four 21" woofers oughtta be able to move some air. [​IMG]
     
  18. Bill Fagal

    Bill Fagal Stunt Coordinator

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    As Alfalfa might say, "And how!"

    (interesting thing: check the specs. They list an efficiency of 104 dB/w at 45Hz--that's just 5Hz shy of the listed upper cutoff! In other words, up on top of the hump induced by the small box. The way some manufacturers cherrypick performance stats makes me giggle.)
     

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