First DIY sub, looking for opinions

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  • JimHal
    Junior Member
    • Dec 2001
    • 2

    First DIY sub, looking for opinions

    I'm in the process of designing my first sub. It's going to be downfiring with the following hardware.

    Dayton 12" DVC driver
    Parts Express 150W Plate Amp

    I've been doing some playing in WinISD and would like some feedback.

    Here is what I came up with so far.

    Volume 117L
    Frequency 20 HZ
    2 - 3" ports (20.4")

    Do you see this being a good design? My main listening is for movies.

    My enclosure will be roughly 19x19x28 with the driver downfiring. These dimensions will best fit in the area I have. The shape will also look
    similiar to my Energy A2+2. I plan to wrap the sub in speaker cloth to also resemble my mains.

    I have been in contact with Andrew Pratt (fellow Winnepegger and a big help), he suggested that the 3" ports may be on the small side. What are the advantages/disadvantages of having two 3" as compared to one 4"? Or 3" to 4" in general?

    Any help would be appreciated.
  • ThomasW
    Moderator Emeritus
    • Aug 2000
    • 10934

    #2
    Hi

    And welcome to HT Guide

    First things first. If you have Microsoft Excel, then download a copy of UniBox. It's more accurate then WinISD.

    I don't have the T/S parameters of the PE DVC driver. I'll grab them and double check your model. I'll add to this thread later today.




    theAudioWorx
    Klone-Audio

    IB subwoofer FAQ page


    "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

    Comment

    • JonMarsh
      Mad Max Moderator
      • Aug 2000
      • 15277

      #3
      I second ThomasW's recommendation for Unibox, the only difficulty being that it is setup for Office 2000 or Office XP; some of the "extra" features implmented in VBA won't work in Office 97. But I love Unibox 3.

      That out of the way, a 3" port, flared, is OK for an 8" speaker system, but not necessarily even a sub using an 8" driver (sounds like an oxymoron to me, but it's amazing what some companies produce). For a twelve, a flared 4" port is the smallest I'd recommend if you want to go ported. You'll have problems with chuffing and compression due to high vent velocity using 3" ports. Also, resistive losses go up with the smaller port, which again detunes the box at higher output levels.

      Since you're planning on a fairly large box for a 12 (a little over 4 cu ft), also consider the construction method. If you elect to go with a box instead of a Sonotube, the best general layout is that used by Ariel in the SW-12, as shown here.




      Then, you won't have problems using a longer, larger port to otpimize the vent characteristics.

      I'm not familiar with the Dayton driver- have you already purchased it? Maybe you want to look at some of the other popular drivers, like the Shiva, Titanic, Blueprints, before committing to a final design. With tools like Unibox, you can explore your options easily, and that's half the fun, anyway.

      Have fun, and good luck with your project.

      Regards,

      Jon




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      Comment

      • JimHal
        Junior Member
        • Dec 2001
        • 2

        #4
        I downloaded Unibox and entered the specs for a 12" DVC.

        The program has recommended a closed enclosure with a volume around 86L with a Qtc of 6.

        A few questions:

        What do you guys think of these numbers?
        Would you recommend a closed before a vented sub?
        Is fill necessary? If so, how much?
        The max power input is 136W. Should I decrease the box size so the max power is increased to around 150W (my amps max)? Would this better protect the driver?

        Thanks for your help.

        Comment

        • ThomasW
          Moderator Emeritus
          • Aug 2000
          • 10934

          #5
          Sealed subs are slightly less efficient than ported boxes. That maybe something to consider with the size of your amp. Don't try to match the Unibox power numbers with the output of your amp. It just doesn't work that way, because you'll get added output from the sub being in the room (aka room gain).

          The "Q" of a sub is one indicator of sound quality. The lower the "Q" the tigher the sound. A "Q" of 0.5 is called critically damped. It usually provides the best sound, but it requires a larger sealed box.

          Other than Andrew we don't have any experience with these drivers so I can't just pull up a design we've already used. There is a Parts Express forum, but it's been down for more than a week. However you can call PE and ask to speak with 'Paul' in tech support. He's a great guy and will be glad to give you recommendations for a box tuning for your needs. You also can of course email him if the #800 number doesn't work in Canada

          With sealed you 'stuff' the box with polyfill at a rate of .5-1.5 lbs/cu ft. With ported you just line the walls of the enclosure with 1-2" of material.

          Don't worry about 'protecting' your driver. It's impossible to overdrive a DVC 12" with 150 watts. You'll overdrive the amp long before you do anything to the woofer. The DVC 12" is rated to 350 watts/voice coil, or 600 watts max.

          Try some models that are ported designs with 4" flared ports (don't worry about the flare just use 4" as the port diameter) This will give you the most output from your amp.




          theAudioWorx
          Klone-Audio

          IB subwoofer FAQ page


          "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

          Comment

          • Jack Gilvey
            Senior Member
            • Aug 2001
            • 510

            #6
            Hi Thomas,

            PE switched servers for the board, but the old address never forwarded to the new one. It was only down for a day or two, I think, here's the url:

            Comment

            • ThomasW
              Moderator Emeritus
              • Aug 2000
              • 10934

              #7
              Hi Jack

              Thanks my old link kept coming up to the we're upgrading page




              theAudioWorx
              Klone-Audio

              IB subwoofer FAQ page


              "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

              Comment

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