First Sonosub Project

Discussion in 'Archived Threads 2001-2004' started by Bob_Sachs, Feb 4, 2003.

  1. Bob_Sachs

    Bob_Sachs Auditioning

    Feb 3, 2003
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    I'm starting on a Sonotube project, having reviewed the various DIY sites on same. Some questions on particular refinements I'm considering, and implementation details.

    1) Resonance reduction: two different approaches I'm considering.
    a) strapping around the outside of the tube with a worm drive hose clamp. Place two or three such clamps around the tube at various node location to prevent vibration. Advantage: very low cost.
    b) "Tube within a tube". Use an 18" inner tube within a 20" outer tube; fill the space with a high density foam. Cons: more cost for tubes.

    2) End caps: the standard approach uses the two end caps glued together. This requires more extensive cutting, routing etc. I propose an end cap using two layers of MDF first bonded together and cut oversize, and then just routing a circular channel 3/4" deep in the bottom side, into which the sonotube is fitted. Use the "flexi" method at to tension down the end caps towards each other.

    3) Reusing existing electronics and woofers: I currently have an Atlantic Technology 162PBM sub (8" and 75 watt amp). I realize that this is on the small end of drivers and amps. But I figure for a first learning attempt I may be better off, to lower my costs. Assuming I can either get or measure the TS parameters, any thoughts on this approach? Would it be best to scale down the tube size?

    Thanks for your collective assistance.

  2. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

    Aug 9, 2001
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    I'm no expert, but I'll try to answer your questions as best I can:

    1.) I've heard of the "tube within a tube" idea before and I'm sure it wouldn't hurt anything (except your pocketbook, like you said), but I'm not sure that anything this extreme is even necessary. In my opinion, the straps may actually weaken the enclosure. Read this. Some information there about standing waves and other items may be helpful to you. The strength of the wall of the tube comes in its uniformity. I believe the straps would weaken the walls by making it non-uniform.

    The standard method of combatting standing waves and resonance is to line the inside of the enclosure with batting that you find at any fabric store. For an example, check Patrick Sun's informative DIY website. Specifically, here and here.

    2.) The channel idea makes sense to me. I don't see why this would create any problems as long as the end cap goes on solid and is air-tight. Caulking on the inside should do the trick, same as the more traditional end cap/end plug method. My only comment is that with your channel idea, I would definitely want to use flexi-type rods to make sure that the end caps will stay on. By using the end cap/end plug method, I was able to avoid putting rods, braces or anything between the top and bottom caps. If you're planning on going "flexi" anyway, then it's no additional trouble.

    3.) It is difficult to say what kind of results you'll have by reusing your existing components in the sonotube. My guess would be that the components are already designed for max performance in their current enclosure. If you use these components, I would suggest building with some contingency plans in mind. Like, don't mount the amp on the box you plan to build (which is difficult on a tube, anyway). Make the sub passive and wire it to the outboard amp and see what kind of performance you get. If you're happy, build a separate plate amp box for the Atlantic Tech. amp.

    Also, build your enclosure so that if it doesn't work out with the AT driver, you can make an easy substitution with a driver that you'll be happier with (such as a Shiva from Adire or an AV12 from Stryke Audio. That way, you're work on the enclosure won't be wasted no matter how the performance is with the AT drivers and amp.

    One last item, like I said, the AT driver and amp are probably already designed for max performance in their current enclosure. This probably includes some boosts at certain frequencies built in to the amp to make up for where the driver lacks. This means that you may not get good results using that amp even with a decent driver. Assuming that you're going for a flat frequency response from the sub, it may be difficult to achieve with an amp that has been wired with such boosts. If you have an old stereo or Pro-Logic receiver sitting around, that would probably be a better choice than the AT amp.


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