Simple(?) DIY sub question

Discussion in 'Archived Threads 2001-2004' started by JonahWicky, Dec 19, 2001.

  1. JonahWicky

    JonahWicky Stunt Coordinator

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    After reading thru these posts until my head was spinning, I decided to go forth with my first DIY sub project. I'm an accomplished woodworker, so building the enclosure is not an issue. Unfortunately, I have no experience in building a speaker. I'm planning to use the Tempest in a sealed box based on the Adire plans, with the PE 250W amp. It will be used primarilly for movies, since my main speakers are a pair of Genesis IIs with an 8" woofer and a 10" passive radiator, which give me plenty of bass for music.

    My question is this...do I need any other parts or components for the subwoofer, like a crossover or equalizer? It seems too simple and cheap with just the driver and an amp!
     
  2. Jeffrey Noel

    Jeffrey Noel Screenwriter

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    Jonah, Welcome to the Forum! [​IMG]
    It's really pretty simple building a sub, that's why the 95L Shiva + PR will be my first DIY project.
    You really don't need a crossover, because if you connect the amp to your receiver's sub out, it will do that itself. You also have one built into your amp, I think.
    As for an equalizer, don't buy one until you build and test your sub in the location that it will stay. When you do this, you will need a tone generator or a bass CD and an SPL meter from Radio Shack. Play a test tone and see what it reads on the meter. Graph this out from 100hz down to at least 20hz. When you have it all graphed out, there may be some humps or dips in the graph. This is when you would want an EQ such as the Behringer Feedback Destroyer, which can "tame" these humps, making the graph closer to flat.
    Hope this helps some.
    I'm sure many more knowledgable DIY'ers will chime in here in a bit.
    Best of luck!
     
  3. jeff lam

    jeff lam Screenwriter

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    Crossover will be included in the Amp and your receiver provided it is DD/DTS. You may want an eq to flaten out the response curve later on if you find your room has peeks and modes but this has nothing to do with the construction of the sub unless you wanted to do a custom eq inside the sub but I don't know if that is good for the eq. Someone else will have to chime in on that. You won't need an EQ however if you are satisfied with the response in your room. It is Ideal to get the flattest response possible.

    edit: Jeff beat me to it.
     
  4. Pete Mazz

    Pete Mazz Supporting Actor

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    The construction is really that simple. The bigger the box, the lower the Q.

    If you haven't already, download and use LSPCad from Adire. Plug in your room dimensions and listener position and then play with sub location. It worked well for me. There's a PDF file that explains it all in the download.

    Pete
     
  5. JonahWicky

    JonahWicky Stunt Coordinator

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    Thanks to all for the advice so far. Now I've got another question.

    If I go with the down-firing sealed box Tempest design, will it make any difference to have it sitting on a carpetted floor, or should I add a solid bottom piece under the speaker box feet? It seems to me that the carpet would dampen the output significantly.

    Any advice is greatly appreciated.
     
  6. Jeffrey Noel

    Jeffrey Noel Screenwriter

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    Well Jonah, from what I've read hear on the forum, it's highly suggested that there should be something solid and flat under the sub. Many people recommend a simple slab of concrete,marble(not for sure on this one), or something of the likes. I think you could find these at Home Depot or Lowes, or any other hardware store.
    Best of luck, and keep the questions coming! [​IMG]
    Happy Holidays!
     

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