Smallest sonotube to reach 20Hz at -3dB?

Discussion in 'Archived Threads 2001-2004' started by Manuel Delaflor, Jun 29, 2002.

  1. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Based on the Shiva, Titanic or any other 12 inch driver, have anyone made calculation on the size of the Sonotube required?

    I have noted, for example, that the HSU's are smaller than the SVS's, still, they appear to reach more or less the same output...
     
  2. Mike_A

    Mike_A Stunt Coordinator

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    well, don't forget that the HSU's have some EQ applied to them, so they can get away with being smaller. the same prinicple is used in linkwitz (sp?) transforum subs that people have built here, allowing for extremely small sealed subs to be flat down to 20Hz. the disadvantage is that a driver with more excursion and high power handling is needed in addition to an amplifier with lots of power. it's basically the same concept you seen in the high end 1000W velodynes, etc...
     
  3. Patrick Sun

    Patrick Sun Moderator
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    And remember, it's not like the sonotube is something special in the way it'll interact with a driver. What you are looking for is the minimum enclosure volume (regardless of it being via a box or sonotube, etc).
     
  4. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Mike_A,
    Thanks, I didn't know HSU used an EQ.
    Jack,
    You always impulse me to do it by myself. I have played with the software, but I don't like the approximate curves it draws, I have learned that those curves rarely reflect real world performance. Anyway, thanks, I guess [​IMG]
    Patrick,
    I know the shape has nothing to do with the sound, but I understand also that it is much simplier and a lot less expensive to have an enclosure strong enough to avoid resonances using a tube than a box. Yep, I will try to find the minimum enclosure volume.
     
  5. Brian Bunge

    Brian Bunge Producer

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    Manuel,

    While a sonotube based sub might be simplier, it's not necessarily less expensive. A sheet of 3/4" MDF costs $20 and should be plenty of material to build most subs including bracing. Of course, if you go huge you'll need more. Some folks have paid upwards of $100 for 24" sonotube and then you still have to buy MDF.

    Brian
     
  6. Jack Gilvey

    Jack Gilvey Producer

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  7. Brian Bunge

    Brian Bunge Producer

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    Jack,
    God, I've missed you around here lately! [​IMG]
    Brian
     
  8. Mark Seaton

    Mark Seaton Supporting Actor

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    It should be understood that if you are really set on a -3dB point of 20Hz, from whatever pool of drivers you find which can meet this spec, those lower in efficiency will allow smaller enclosure volumes. This is where the Stryke SA-1204 is a nice solution with a little more power. If you have power, a Brahma sub should get you into even smaller box sizes. Obviously you then run into the problem of adequate porting fitting within the box.
     
  9. Bob Bartlett

    Bob Bartlett Stunt Coordinator

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    I found a cheap way to get sonotube is look around construction sites and ask a worker if they have any pieces left over. A construction crew was at my local school and I asked one of the workers and he gave me a 6' piece of 18" tube for free. Just a thought. The local lumberyard wanted $89 for a 12' 18" tube. I can buy 4 sheets of mdf for that.
     
  10. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Brian Bunge
    In my case, it is really really cheap, I just bought a sonotube, 12 inch and 3 meters tall, I cutted it in three pieces. Total cost? 15 bucks. Today I asked for the price of three cuts on MDF with all the holes needed, it doesn't pass 30 bucks.
    Im searching at this moment for an used home amplifier which I can put in Mono and don't want to pay more than 80 bucks. What I need now is only the driver, I will begin my experiments with national (Im in Mexico) drivers which cost from 14 to 50 bucks, and then, when I feel confortable I will ask for a Shiva or a Tempest and a good amplifier to make my final sub. Cost in here for a box would be higher, around 70 to 150 bucks.
    Jack Gilvey
     
  11. Brian Bunge

    Brian Bunge Producer

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    Manuel,

    I'm interested in seeing how you plan to mount a 12" driver in a 12" tube! The driver's outside dimensions are usually slightly larger than 12". For instance, a Dayton DVC 12" driver has an external diameter of 12.25", which means it would overhang the outside of the tube. You'd have to make your exterior piece of MDF around 12.5-13" in order to mount the driver. Then you'd see the screws sticking up out of the MDF.

    I don't know of a $15-$40 driver that's going to meet your requirement of -3dB at 20Hz at any audible levels in a home environment.

    Concerning your friend's sub, unless the software you used can simulate the cabin gain that you get when you put a sub in an automobile then there's no wonder you didn't get a response curve anywhere near what the simulation said. The response curve would look absolutely nothing like a simulation that doesn't factor in cabin gain.

    Brian
     
  12. Jeff Rosz

    Jeff Rosz Second Unit

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    regarding trusting of software, i think everyone can mostly agree that lspcad is pretty darn accurate. and the cost of using lspcad obtained from adire when using adire drivers cant be beat.
    brian, he could just double up on the thickness of the external driver endcap. a lil mass there wouldnt hurt.
     
  13. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Brian,

    I bought the 12" just for begin to experiment, the next step that was available at the store was a 20something, way to big for my first approach.

    The drivers Im seeing for now (again this will be previous to thinking in import a more expensive driver) are 8" and 10", I forgot to mention it!

    Yes, he didn't simulate the cabin gain, his software doesn't allow to do that. And this was his first design too. I wasn't aware that such measure could be introduced in some programs, I will comment him.

    Jeff,

    Thanks for your imput, I will begin to calculate using the version from Adire. Last time I did it was calculating a sealed box for a Tempest, and it was large. Im considering two possibilities at the momement, either a small sonotube, or a closet with concrete walls to do an IB array.
     
  14. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Jack,

    Why ALWAYS this tone in your replies to me? You seem to remember well everything I asked before. Am I stubborn? Or you simply don't like me?

    Why even bother to answer anything I post?
     
  15. Bryan Michael

    Bryan Michael Supporting Actor

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    how about a 15 inch driver in a 12 inch tube?


    just buld a box on the end of the tube and you can buld a box on the other end for balance and there you have it a 15 in sub in a 12 in tube
     
  16. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Jack, you're mighty feisty in this thread. Did you have an extra latte at Starbucks? I'm so glad you're hanging onto your altruism - the warmth of your personality would be sorely missed without it. [​IMG]
    I try to ignore the abuse. Notice how much Jawga Brian B. abuses me constantly? I'ts the unrepressed envy - he wishes he lived in Texas. I remain above such pettiness.
     

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