Why dont I ever see a Tempest w/ 1 PR?

Discussion in 'Archived Threads 2001-2004' started by Scott Simonian, Sep 30, 2001.

  1. Scott Simonian

    Scott Simonian Screenwriter

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    I was just thinking about this while I was strolling through Adires DIY section. Checking out the Shiva and Tempest designs. I noticed that all Tempest based PR designs had (required?) 2 PR-15s on them.
    Now, I dont know everything about PR designs but I dont see why just having one PR wouldnt be bad. But I dont know. I dont.
    I just was curious. I would think that when you have one the Tempest would have an easier time driving just one. If it does have a hard time driving two.
    I dont know, I am just curious.
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    Yes, these are bruises from fighting. Yes, I am comfortable with that. I am enlightened.
     
  2. Chris_Brunhaver

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    Well, a good rule of thumb for using PR's is having about 2.5 times more PR displacement than woofer displacement. Of course the PR excursion will vary with how you tune it. That is why you need two PR-15's to one tempest.
    -Chris
     
  3. Scott Simonian

    Scott Simonian Screenwriter

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    Thats about waht I thought.
    What would happen if you did use just one PR?
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    Yes, these are bruises from fighting. Yes, I am comfortable with that. I am enlightened.
     
  4. Patrick Sun

    Patrick Sun Moderator
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    You also want to balance the excursion from the PRs, so you will see them used in pairs on adjoining sides from the driver itself.
     
  5. Jack Gilvey

    Jack Gilvey Producer

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    One Adire PR-15 doesn't really have the displacement required for the Tempest (not quite 2x by my reckoning), so it will frequently be driven into overexcursion, compression, and likely quick destruction. The active driver doesn't "drive" the PRs, they don't present a load to the driver, really, and more is better to a point. 3-4x the driver's Vd is frequently recommended.
    The limiting factor in the number of PRs one can use is frequently the amount of added mass they can handle. In much the same way as adding diameter to a port necessarily increases its length for a given tuning(Fb)/box size(Vb), doubling the number of (identical) passive radiators requires a doubling of the mass (Mms) of each, and there's only so much a given PR can handle.
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    [Edited last by Jack Gilvey on October 01, 2001 at 07:05 AM]
     

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