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How much mass to add to my PR?

Discussion in 'Archived Threads 2001-2004' started by Jeffrey Noel, Jan 25, 2002.

  1. Jeffrey Noel

    Jeffrey Noel Screenwriter

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    Well, I will be getting my PR in a couple of days that I ordered from Kyle at acoustic-visions.com, but I don't know how much mass to add to it. So here's the setup:

    I built the 95L Shiva + PR design provided on Adire's site, but I ended up getting the PE 12" DVC instead of the Shiva. This is because I didn't want to wait until March to get my sub up and running! I've also heard that these two subs are quite similar. So, how much mass should I add to the Adire 15" passive radiator for the best overall sound? I wish I knew how to figure this out myself, but I'm sure one of you "experts" could help me out much quicker!

    Thanks a lot!
     
  2. John E Janowitz

    John E Janowitz Second Unit

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    Hi Jeffrey,

    Too bad you already picked up the Adire PR. I still have some Bstock PR's here for $25 each. You could have picked up a pair of them for about half the price of one of those.

    In any case, in 95L, you'll want about 600grams total on that PR. This gives an Fb of 21Hz and gives an F3 of 20Hz. You'll have good power handling down to this range, however you will be able to bottom the single PR pretty easily with any tones below Fb. I always go with daul PR's to keep from running out of excursion.

    John
     
  3. Jack Gilvey

    Jack Gilvey Producer

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  4. Ron Shaw

    Ron Shaw Stunt Coordinator

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    With a vented system, its very important to use a subsonic filter to remove signals below Fb. These signals are of no benifit, and just add distortion (and can damage drivers). A 2nd order filter minimum is recommended. This can be constructed easily using a single op amp.
     
  5. Jeffrey Noel

    Jeffrey Noel Screenwriter

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    Thanks for the reply John and Jack! I just can't wait to get this sub playing in my cell..er..dorm room! [​IMG]
    John, I just read one of your posts on another topic regarding your B-stock PRs. I nearly cried. [​IMG]
    But don't worry, this will not be my only sub! It's only the beginning! [​IMG]
     
  6. Jeffrey Noel

    Jeffrey Noel Screenwriter

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    When you say 600 grams total, how much does that mean I need to add? Do I just add 600 grams? Or is there already some mass on it?

    Sorry!
     
  7. Jack Gilvey

    Jack Gilvey Producer

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  8. Ron Shaw

    Ron Shaw Stunt Coordinator

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    Sorry for the confusion. I wasnt talking about the PR as much as the need to filter the subsonics from a vented system in general. I dont know if the DIYers in this forum are aware of this, so thought I would mention it.
     

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