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NRNP (No Router, No Problem) Computer Sub Build Thread

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  • NRNP (No Router, No Problem) Computer Sub Build Thread

    This project started off with a desire to add a little bottom end to the tiny 2" full range computer speakers I'm currently using, but it evolved into an exercise in simplicity. The only tools required for this project are a circular saw and a triangle square. A drill, clamps and a sander would make the project a little easier, but they are not necessary.

    The main ingredients are the Tang Band W5-1138SM and the Dayton Audio SA25 plate amplifier. The ferrite version of the woofer (W5-1138SMF) can be used at a significant cost savings, but it will sacrifice some air volume, which is already in short supply. As such, I used the neo version for this project.

    The enclosure is constructed from a single piece 1 x 8 board, which is actually 0.75" x 7.25" - the perfect width to allow my triangle square to be used as a straight edge for the circular saw, keeping every cut perfectly square. I used a 3ft long piece of poplar to create the top, bottom, 2 sides and 4 corner braces. The amp serves as the rear panel and the front corner braces create an octagonal opening that is close enough to a circle to be used as the woofer mounting hole.

    More pics to come...
    Attached Files
    _____________________________
    Tall Boys
    NRNP Computer Sub
    The Boxers
    The Hurricanes
    The Baronettes
    Conneccentric
    UX3

  • #2
    Re: NRNP (No Router, No Problem) Computer Sub Build Thread

    First things first, I squared up the end of the board using the triangle square as a straight edge.
    Attached Files
    _____________________________
    Tall Boys
    NRNP Computer Sub
    The Boxers
    The Hurricanes
    The Baronettes
    Conneccentric
    UX3

    Comment


    • #3
      Re: NRNP (No Router, No Problem) Computer Sub Build Thread

      Then I cut my 4 corner pieces as shown in the pics. The 1.625" dimension is critical to make the octagonal opening small enough to seal the woofer in. If anything, go a little big on these, then you can file away material to get the woofer to fit. I cut mine pretty close to the right size and had no issues.
      Attached Files
      _____________________________
      Tall Boys
      NRNP Computer Sub
      The Boxers
      The Hurricanes
      The Baronettes
      Conneccentric
      UX3

      Comment


      • #4
        Re: NRNP (No Router, No Problem) Computer Sub Build Thread

        Then I glued up the 4 sides, glued in the 4 corners and put some weather strip on the woofer flange (I think it was 3/8" x 1/4") to make sure it sealed well in the non-circular opening.
        Attached Files
        _____________________________
        Tall Boys
        NRNP Computer Sub
        The Boxers
        The Hurricanes
        The Baronettes
        Conneccentric
        UX3

        Comment


        • #5
          Re: NRNP (No Router, No Problem) Computer Sub Build Thread

          Nothing left to do but mount the plate amp on the back, wire the speaker, add a little pillow stuffing and mount the driver.

          This is for sure the easiest and one of the most rewarding projects I have ever done. The whole project took about 3 hours from start to finish including a trip to Home Depot and waiting for the glue to dry in between steps. And before anyone gets bent out of shape about a "sub" that models with an F3 of 70Hz, keep in mind that if it's on the floor against a wall, as most computer subs will be, then the sealed alignment really gets filled in nicely by the boundary reinforcement and rounds out the sound of my 2" full rangers VERY nicely.

          I believe the Qtc should be somewhere around 0.80-0.85 with the amount of stuffing that I added. I didn't want to get too crazy with it though, so as not to smother the amp electronics. For what it is, this thing sounds great!
          Attached Files
          _____________________________
          Tall Boys
          NRNP Computer Sub
          The Boxers
          The Hurricanes
          The Baronettes
          Conneccentric
          UX3

          Comment


          • #6
            Re: NRNP (No Router, No Problem) Computer Sub Build Thread

            that's really nice Dan. good job.
            " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

            Quote Originally Posted by hongrn. Oct 2014
            Do you realize that being an American is like winning the biggest jackpot ever??

            http://www.midwestaudioclub.com/spot...owell-simpson/
            http://s413.photobucket.com/albums/pp216/arlis/

            Comment


            • #7
              Re: NRNP (No Router, No Problem) Computer Sub Build Thread

              Wow, your limited tools resulted in way better results then some of my first attempts. Lets just say, I never shared any of my earlier work.

              How much bass does it put out in that tiny box?

              Comment


              • #8
                Re: NRNP (No Router, No Problem) Computer Sub Build Thread

                Thanks guys. I've got more tools, but I thought it would be cool to design something that even folks with a stripped down tool set could build especially so easily and cost effectively. The output is honestly unbelievable considering it is a 2.5L enclosure. There are commercially available computer subs this small, but they all have 3-4" woofers with 3-4mm of xmax. The NRNP computer sub has a legit 5" woofer with 9mm of xmax crammed into a box that shouldn't be big enough, but it is.

                This is probably the most output you could possibly get out of a box this size without some crazy DSP - it's just good luck that the flange and basket are sized such that it can be mounted the way it is in a box that just so happens to fit the amp perfectly too. A lot of dimensions and parameters really had to fall into place for this project to be possible.

                Dan
                Last edited by DanP; 07-02-2013, 08:31 AM.
                _____________________________
                Tall Boys
                NRNP Computer Sub
                The Boxers
                The Hurricanes
                The Baronettes
                Conneccentric
                UX3

                Comment

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