Another Tempest project about to get under way

Discussion in 'Archived Threads 2001-2004' started by Owen Bartley, Dec 23, 2002.

  1. Owen Bartley

    Owen Bartley Second Unit

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    OK, I'm seeking all the expert advice I can find now, since I'm finally almost ready to start. I've been researching and playing around for a couple of months now, and after starting out with a small Shiva design, I have logically come to... a 210L Tempest! But there are a couple things I need straightened out before I get going.
    1. Should I account for the volume taken up by the port in my tuning calculations, or just the driver/amp/bracing? (i.e. should I subtract port volume from the box and then re-tune based on the new volume?)
    2. What are the diffs between the PE and Adire 250w amps? Is it that the Adire has the rumble filter? I ask because I can order the Adire from CSS, but not the PE amp, which is cheaper, but the extra shipping/brokerage/duty costs would probably make the cost similar in the end.
    3. Is the rumble filter even neccessary for a tempest of my design?
    To help answer this one: the box I modeled in LspCAD shows xmax being fine until it gets down to 15Hz and below. Does my 18Hz tune mean it will start rolling off before xmax and it should be safe? or would a rumble filter prevent this sub from overextending and possibly damaging itself?
    and LAST... I'm waffling on the design. I put up renderings of my choices at my website under the SUB page. Please, give me your opinions! Just looking for an outside perspective here since I had a bunch of ideas.
    Thanks everybody!
    (oh, and sorry for the few people who have to read my cross posting)
     
  2. Patrick Sun

    Patrick Sun Moderator
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    1. You must take into account everything that takes up volume inside the enclosure, and that means treating the port as a solid object in volume calculations.
    2. You can modify the rumble filter on the PE amp (their website even tells you how in the specs pdf file for the 300-794 plate amp from PE. PE is shipping amps with no boost nowadays. The rumble filter helps in not driving the driver hard for subsonic frequencies below 20Hz. The Adire version is probably the same amp with the rumble filter mod in place as well. You could use the PE spec sheet if you wanted to play around with the base boost / rumble filtering.
    3. Rumble filtering just below 20Hz is a good thing for driver protection on the DVDs with the truly low end bass content at high amplitudes. Remember, below port tuning frequency, the enclosure/port doesn't provide the driver with any more "protection" so it's up the rumble filter on the amp to cut down the amplitude of the low frequencies that can over-drive the driver in stressful playback situations.
    4. As long as everything fits on the bottom side, you should be good to go with the bracing in depicted in the wire diagram. Your webpage doesn't have a "Sub" page, only Home and HT pages.
     
  3. Owen Bartley

    Owen Bartley Second Unit

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    Thanks Patrick, I'll work all that stuff in. And sorry, the link doesn't show up sometimes, usually in smaller windows, but the page is here... http://www.geocities.com/needfiles1/sub.htm
    If anyone else is having problems with links, the HT page (with the wireframe drawing) is here http://www.geocities.com/needfiles1/ht.htm
    And If I get truly inspired during my creation process, that just might be the future home of a construction documentation almost as extensive as all yours are. [​IMG]
     
  4. Wayne Ernst

    Wayne Ernst Cinematographer

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    Owen,

    I like the designs that you've created with lspCAD. Pretty cool stuff.
     
  5. Owen Bartley

    Owen Bartley Second Unit

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    Thanks Wayne.

    Just wanted to give my message a bump, and to wish everyone a Merry Christmas, or happy holidays!

    Any opinions on what design people like the most?
     
  6. Patrick Sun

    Patrick Sun Moderator
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    The latest design #3/#4 looks nice.
     

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