Is there any reason not to build a huge Sonosub?

Discussion in 'Archived Threads 2001-2004' started by Jeremy Illingworth, Sep 20, 2001.

  1. Jeremy Illingworth

    Jeremy Illingworth Supporting Actor

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    I've gotten the hang of Adire's CAD and was playing around with the box size. I found a place in town that has 24 inch diameter Sonotube. At 48 inches tall that's 355 liters. An 8 cm port seems to work best. On the graph it appears to go very low with good SPL all round. I could easily add another foot of height onto the tube for 444 liters. Other than the size of the tube, is there any reason not to build one so big?
    jeremy
     
  2. Dustin B

    Dustin B Producer

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    Once you pass a tube that is 5' in length there arises the possiblity of half wave length resonances forming in the tube. Roughly at 5' it would be 110hz and at 6' it would be 90hz. If your crossover is 80hz or higher this could become an issue. If your crossover is at 60hz or lower, then it shouldn't (unless you start going past 6').
    Anyways, I wanted a sub with a small foot print and height didn't matter to me. So I went with 18" sonotube and made it 5'2" long to give me a net volume of 260L (overall my sub is 5'11" tall). On the suggestion of Dr. Hyre of Adire I placed insulation about a foot thick in the top of the tube. I haven't had any problems with my 80hz crossover and resonances.
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    Dustin
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    My Adire Tempest Sonosub
     
  3. Neil Joseph

    Neil Joseph Lead Actor

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    Question, I am using eggcrate foam to insulate the sides of my sonotube. I wanted to use baffling to insulate the endcaps. Is there a point where a sonosub can be over-damped. Should some of the hard surface be visible?
    orangeman
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  4. Jeremy Illingworth

    Jeremy Illingworth Supporting Actor

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    So if I kept it at 24 inches diameter and four to five feet (355 to 444 liters) all should be well? I was going to use a Tempest.
    jeremy
     
  5. Greg Monfort

    Greg Monfort Supporting Actor

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    >Is there a point where a sonosub can be over-damped. Should some of the hard surface be visible?
    ====
    You bet! http://geocities.com/kreskovs/Box-1.html
    GM
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    Loud is beautiful, if it's clean
     
  6. Dustin B

    Dustin B Producer

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    I seem to remember being told that keeping the length under 4.5' would be the safest bet. From resonance calculations I'd have to agree.
    Although I've learnt a lot over the last 5 months, I'm still not entirely sure of the effects of VAS on deciding on an enclosure size.
    So to those who know more, are there any advantages disadvantages to having a vented enclosure that's volume is larger than the VAS of the driver being used?
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    Dustin
    [email protected]
    My Adire Tempest Sonosub
    [Edited last by Dustin B on September 21, 2001 at 12:30 AM]
     
  7. Martin Phillips

    Martin Phillips Auditioning

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    Dustin is asking the answer to question I would like to know. Is there a negetive or positive effect if the sub volume is larger than the vas of the driver? More specifically I would like to know the maximum volume I can usebefore it becomes a negative for an encloser for a shiva driver tuned to 19hz? thanks
     
  8. James W. Johnson

    James W. Johnson Screenwriter

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    >Is there a point where a sonosub can be over-damped. Should some of the hard surface be visible?
    ====
    You bet! http://geocities.com/kreskovs/Box-1.html
    Pay particular attention to this section...
    One of the problems with an unlined box, which would typically have the largest value for Qb, is that with little or no absorsion of the acoustic energy from the back of the driver, there may be a significant amount of midrange sound emanating form the port. While typically not a problem for ported subwoofers, this can color the sound of the speaker undesirably when the woofer is also call upon to reproduce the lower midrange response. One solution is to place the port on the back of the enclosure. This may help, but may not sufficiently reduce the midrange port radiation. Another approach is to line the box with damping material. However, the danger here is that if the damping material used is excessive, and there is significant absorption of acoust energy at and around the box tuning frequency, Qa will become significant and the effectiveness of the box as a resonator will be compromised. The reduction of Qa affects the response mainly above fb. In extream cases the effect may be so dramatic that the response of the system may be degraded to the point where it defeats the purpose of using a vented box design.
    In other words a properly designed vented subwoofer needs zero lining whatsoever.
     
  9. James W. Johnson

    James W. Johnson Screenwriter

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    355liters should work well with a single Tempest I can't see any benefits of going any larger, an 8cm port is WAY too small though, use a 20.3cm port for best results.
     
  10. Neil Joseph

    Neil Joseph Lead Actor

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    When I saw that 8cm port, I immediately thought that wa way too small a diameter. Probably he meant 8" diameter.
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  11. Jeff Rosz

    Jeff Rosz Second Unit

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    so the question is: whats the difference between a 317 liter and 355 liter tube in this application(same tune)? answer: 38 liters. there is almost no difference in performance between the two.
    [Edited last by Jeff Rosz on October 12, 2001 at 03:51 AM]
     

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