Adire 15" Passive radiators (displacement and massing)

Discussion in 'Archived Threads 2001-2004' started by Seth_L, Jan 30, 2003.

  1. Seth_L

    Seth_L Screenwriter

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    Does anyone know how much box volume (Liters or Cu-ft) the Adire PR15's displace? My box design has 4 PR15s and I need to know how many liters I need to factor in for them. I'm guessing maybe about 3-4L each, but I don't really know. That's pretty much just a shot in the dark.

    Also, what's the best way to add mass to a PR? I need to add 1115 grams to each of the 4. Lead? Washers?

    Seth
     
  2. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Seth,

    I can't speak to the Adire PR's, but John from styke is sending me a 2" diameter steel weight and some gorilla glue.. I think though you can use anything: washers, lead, even spare change. even though you might not have any left after you build the sub [​IMG] just make sure it is secured good, don't want anything poping loose during Lord of the Rings at reference, hehe..

    Craig
     
  3. Seth_L

    Seth_L Screenwriter

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    Craig,

    Maybe I should use gold. We all know what wonders gold does for interconnects it's gotta have an even bigger effect on PRs. [​IMG]

    At this point I think I just want something cheap and heavy. Hmm...

    Seth
     
  4. Greg Yeatts

    Greg Yeatts Second Unit

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    Seth

    I used the Jasper Jig and cut a MDF disc that fit snugly in the cardboard tube on the PR15. I then drilled a hole that is the diameter of a large bolt in the middle of the mdf disc. I then drilled a hole halfway throug the disc (through the hole that was the diameter of the bolt that I drilled earlier) that was the diameter of the FLATS on a nut that fits the bolt. I then used some epoxy on the nut and used the bolt to pull the nut into the mdf disc (into the hole that was the diameter of the flats on the bolt. This makes the nut fit into the disc very tightly.

    I then epoxied the mdf disc into the cardboard tube on the bolt. You can now attach some fender washers to the bolt and tighten the bolt with the fender washers into the nut that's in the mdf disc that you epoxied into the cardboard tube.

    You need to weigh each of the components including mdf, bolt, nut and fender washers to determine how much weight you are adding to th PR. This also alllows you to change the weight on your pr to see which tuning you like best.
     
  5. Craig Woodhall

    Craig Woodhall Supporting Actor

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  6. Tom-K

    Tom-K Stunt Coordinator

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    Hey Seth, I'm assuming your using four of these for you Tumult? What size of box and tuning freq are you planning on utilzing with 4 PRs? I've got 2 tumults coming, and had originally planned on using a IB, but that is no longer an option so back to the drawing board.
     
  7. Seth_L

    Seth_L Screenwriter

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    Tom,

    Right now it looks like I'm going to use a 225L box with each of the PR's maxed out at 1.5kg. This should (per WinISD Pro) have a Fb of 17.28Hz. It should give me a -3dB of 15.7Hz. I'm working off the assumption that 50Hz is 0dB, not -1dB as the software says. 0dB is at 200Hz, which the sub won't be playing, so I've considered 50Hz to be 0dB rather than -1dB. Anyhow it should have a lot of slam with a QSC PLX2402 behind it.

    Seth
     
  8. Seth_L

    Seth_L Screenwriter

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    Greg,

    I like your idea.

    What about the box volume displaced by each PR though? Is it negligable, or should I consider it?

    Seth
     
  9. Kyle Richardson

    Kyle Richardson Screenwriter

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    Seth,
    I wouldnt worry about the displacement taken by the PR's too much, but it is something to consider since you will be using 4 of them. I'm not positive, but if I had to guess I'd say it only about 2...maybe 3 liters per PR since there isnt a motor structure.
     
  10. Craig Woodhall

    Craig Woodhall Supporting Actor

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    yes, that is what JohnJ from Stryke told me.. since there isn't much inside the box, it is negligible.. maybe with 4 you might want to add a couple litres like Kyle said..

    Craig
     
  11. Greg Yeatts

    Greg Yeatts Second Unit

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    Seth

    I e-mailed Adire and they gave me the displacement for my calculations. I may have that e-mail at work. I will check tomorrow. If you are in a hurry, e-mail Adire, they have good customer service and will reply promptly.

    I like my way of adding mass because it allows you to easily change the mass on your PR. My explanation of how to do it is harder than the actual process. It took me about 15 minutes to cut out the disc and epoxy the nut in the disc and expoxy the disc in the PR.
     
  12. Tom-K

    Tom-K Stunt Coordinator

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    Seth,

    A couple more questions if you don't mind. What Q will your enclosure yield? How much power are you going to use, and are you going to be having the tumult down firing? I appreciate your help.
     
  13. Ken_R1

    Ken_R1 Auditioning

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    Aren't all of the specs you need located here on their website. They list Vd as 5.1 liters and give a desscription of how to add mass to the PR15.
     
  14. Seth_L

    Seth_L Screenwriter

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  15. Seth_L

    Seth_L Screenwriter

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  17. Seth_L

    Seth_L Screenwriter

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    I don't know Anthony. Too much of that attached to a PR and the entire space time continuum (sp?) could collapse. You gotta be really careful.

    Seth
     
  18. Tom-K

    Tom-K Stunt Coordinator

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    Seth,

    Question since you're using two on both sides, why did you choose Adire's 15s versus the Stryke 18s. As I understand it you could get by with 2 Strykes for less money.
     
  19. Craig Woodhall

    Craig Woodhall Supporting Actor

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    I opted for the dual 18's just because it was more affordable for me.

    Craig
     
  20. Seth_L

    Seth_L Screenwriter

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