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building a diy ISO box?

Discussion in 'Backline' started by aviel, Sep 25, 2012.

  1. sprack

    sprack Thread Killer

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    It is, but a muffler is easier to design since you just want to kill as much of the sound as possible and then just keep backpressure. An isocab has to muffle the outbound while preserving it internally and just attenuating properly. My supposition on why the Rivera design sounds better is that it doesn't provide back pressure, like a room.

    I hope the sketchup file is useful to you.
     
  2. 006

    006 Member

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    Thanks dude :) The SM57+V30 sounds pretty good. You should get some clips of this thing in a mix. :D
     
  3. Benqbasic

    Benqbasic Member

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    Wow, really nice work. I have been interested in how the silent sister works since it came out.

    Just a question about your statement above.
    Is the port tuned like you would a 'transmission line speaker' setup?
    Did you use an online calculator of some sort for the tuning?
     
  4. sprack

    sprack Thread Killer

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    I used the bandpass cab calculator since it's closest in design to the isocab. The tricky question is where to tune it. I tuned mine for 40Hz. My logic was that I wouldn't be running a bass guitar through it, it was low enough to not interfere with the frequency range I was interested in and the air gap was wide enough that everything else should be able to breathe.

    Here's the calculator I used.
    http://dbdynamixaudio.com/4th-order-bandpass-enclosure-calculator/
     
  5. TheWinterSnow

    TheWinterSnow Den Mørke Natt

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    I was thinking, with the standing waves issue and box size, you could build a false wall out of some 705 and suspend it in a deadzone with floor isolators, with the space between the false wall and the box itself, you could absorb the lows and and even get rid of standing waves even though you have a square box. You could take it a step further and leave open room at the opposite wall from the speaker and run a labyrinth up and across the entire top of the box lined with cellulose or more 705.

    Something like this:

    [​IMG]

    Basically you would have a large Isobox with a floating room within it being made out of bass traps, if the density of the 705 is thick enough to absorb low frequencies, you remove the boxiness, then adding the oversize vent allows the depressurization with minimal volume as there would be more surface area for the 705 to absorb. Due to the deadspace you would not need as much space inside the isobox relative to its performance.

    The sketch is just a side dissection with no bracing design, something of that sort would have to be done with a cad program or Sketchup, I was merely throwing the idea out there.
     
  6. sprack

    sprack Thread Killer

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    I agonized on the standing waves quite a bit during the design, but came to the conclusion that in a box that small it'd be very hard to find and diagnose. But I like your idea, its a good one. On the backside of that false wall I'd want to make the labyrinth as tubular as possible to channel what sound was in the wavelength that wouldn't pass straight through to reflect away. So basically strap a sousaphone to the top.
    One design thing about that, you'll have to make the lid on the side then. And its still kinda a bitch to get a speaker in and out. If you build one, put the bolts for the speaker facing up so its easier to guide the speaker onto it. Cover the insulation with something like burlap or some other open weave. Stuff snags on the insulation all the time while working in there. And get some #6 copper if you use goosenecks, feed it up the middle of the gooseneck. It makes it hold its position.
     
  7. sprack

    sprack Thread Killer

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    That looks similar to some of the coffin style cabs I've seen people build. I think it'd be a good idea to try and relatively easy to build. I'd add MLV along with the 705 if you wanted kill any resonant effects. I'd also angle the walls facing the cab for maximum wave trapping. Are you thinking of putting a full cab in there (Xx12)?
     
  8. TheWinterSnow

    TheWinterSnow Den Mørke Natt

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    My idea was more along the lines something big enough to fit an entire 412 in there and have enough room for two boom mic stands. We are probably talking dimensions like 6X4X4 which is pretty decent sized, maybe a tad larger than the ATX Isobox posted on the first page, with 4 inch thick 705 bass traps, 4 inches of dead space, with another 2 inches of 705 is plenty of absorption, not to forget the cab will be a good three to four feet away from the bass trap, if there was going to be any standing waves, it would look better than my recording room.
     
  9. StayTrue

    StayTrue Member

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    I built something similar; I'll post some pics when I get home. One thing I will say, the box will be extremely heavy. I estimate the one I built weighs roughly 500lbs(not including the cab), but I think it works great. Bracing adds a ton of weight......
     
  10. StayTrue

    StayTrue Member

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    Pics:
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    The black material is called Acoustiblok. I placed the port on the top panel (in front of the cab), and it exits on the back side of the panel(above the cab).
     
  11. AD Chaos

    AD Chaos MGTOW

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  12. StayTrue

    StayTrue Member

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    This was right after I built it(literally). This should give you an idea of how much attenuation I get in the room, but I'll throw some clips with it mic'd up in the next few days.

    I should note there is still some attenuation with the sides still up. The post volume on the Peavey was ~2.5.
     
    #52 StayTrue, Oct 17, 2012
    Last edited by a moderator: Nov 19, 2015
  13. StayTrue

    StayTrue Member

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  14. AD Chaos

    AD Chaos MGTOW

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    Thanks much!

    That box isolates a lot! The clip sounds a bit undergained, though (on cans at least)
     

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