Oops! I did it again: Sunosub III.

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  • Patrick Sun
    Super Senior Member
    • Aug 2000
    • 1380

    Oops! I did it again: Sunosub III.

    After using up almost 9 feet of sonotube on Sunosub I and Sunosub II, I still had a 27" section left over, so what the heck, let's build one more sub!

    Okay, boys and girls, here's the 1st installment of photos of my progress on constructing Sunosub III:

    I'm using the Tempest 15" driver from Adire Audio (formerly Avatar Audio). Just to recap the design specs for this effort:

    1 Tempest 15" driver
    1 4" ports 21" long (probably going with a flare port kit) - tuned enclosure to 16Hz
    5.75 ft^3 of internal volume
    24" wide sonotube roughly 25.25" tall before endcap thickness.
    3/4" thickness of MDF endcap on each end to conserve internal volume.

    Here we go:

    Day 1 - I go shopping 9-13-00

    The raw materials:

    Photo 1 : Here's the cut pieces of MDF. I went to Home Depot, and bought a 49'x97' section of MDF and had Home Depot cut it into 2 pieces of 28"x28" (I plan on having a 27" wide table top on the sub, and also for the bottom endcap), and 2 pieces of 25"x24" for the internal endcap on both ends. I wound up with some excess MDF as you can see.

    Photo 2 : Here's a close-up of the 2 pieces of 28"x28" MDF, 2 pieces of 25"x24.5" MDF, and 1 piece of 24"x24" of plywood (for screwing/glueing in the T-nuts for the driver holes).

    Photo 3 : Since I have stuff left over from the previous Sunosub efforts, here's what I picked up - Wood glue, Silicone caulk, beefy 6" table legs, leg mounts, enough 2" 10-24 machine screws (for leg mounts, driver screws) and 8 10-24 T-nuts, enough 2.5" 10-24 machine screws (for the terminal cup).

    Photo 4 : Here's a look at the sonotube-like material that was left over from the last two Sunosub projects: 27" of sonotube.

    I'll probably take a leisurely stroll on this project. Again, it'll feature some different challenges. I think I'll go with a piano black table top cover, and perhaps use a black sock to cover the sonotube. The top cover will overhang the sonotube by 1.5" all around (I might stick to an overhang of 1" though).

    The tune might be asking a little too much for a 5.75 ft^3 enclosure for the 15" Tempest driver, and I might pick up more port noise than optimal, but I'll get to see how adversely port noise will affect the overall sound quality of this subwoofer in normal operating conditions.

    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
  • ThomasW
    Moderator Emeritus
    • Aug 2000
    • 10934

    Hello, my name is Patrick, and I'm a "sub-o-holic".

    Step #1 Admit you are helpless.........:B


    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


    • Patrick Sun
      Super Senior Member
      • Aug 2000
      • 1380

      Hey, I've run out of sonotube, so I think this will be the end of Sunosubs unless a friend wants me to help them.

      PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
      PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs


      • Mike Temple
        Junior Member
        • Sep 2000
        • 18


        The 1.5" overhang may look better because of the size of the tube. It may help to "hide" the base a little, as with a larger overhang, it will probably look more like a conventional piece of furniture.

        The piano Black looks great but without multiple coats of hard clear, it is easily damaged or scuffed. A corner table away from high traffic might work but as a main table with high traffic it may be scuffed up pretty easily.

        Formica laminate may work as an alternative with a stone or marble look, and is pretty easily applied with a router trim bit.

        Just one other thing to consider....


        • Patrick Sun
          Super Senior Member
          • Aug 2000
          • 1380

          Day 2 - 9-16-00

          It's a nice breezy Saturday, but I managed to get the tops of my feet sunburned because I was wearing flip-flops.

          Since this design is a little different from the previous designs, I will only have a 3/4" layer of MDF on the inside of the top and and a 1" (3/4" MDF plus 1/4" plywood) bottom endcaps because I'm trying to conserve as much internal volume as I can.

          This means I'll be cutting each layer's endcap individually because they will have different widths to them. The outer top endcap will be around 27" wide, the outer bottom endcap will be 24.5" wide (just flush enough to provide a ledge for the sonotube material) and both inner endcap will be roughly 23.75" wide.

          Photo 5 : The Power Tools - Skil Router 1823, Black & Decker Power Drill, B&D Jigsaw, Ryobi Orbital Sander - all bought on previous Sunosub I construction in July.

          Photo 6 : I start on the inner top endcap (with the help of The Hollow Man again) and find the center of the MDF board and mark off the radius for use with the plunge router.

          Photo 7 : I do the same for the inner bottom endcap (denoted by its plywood layer on the inside).

          Photo 8 : The routing for the inner bottom endcap begins.

          Photo 9 : Once I finish the inner bottom endcap, I test for fit by using a 4" piece of sonotube from my previous Sunosub construction. I find that I'm off by about 1/4" in width, but have no fear, I'll fix that later with wood filler.

          Photo 10 : Now I start on the inner top endcap.

          Photo 11 : Once I finish the inner top endcap, I test it for fit, and it fits better than the inner bottom endcap, so no wood filling will be required.

          Photo 12 : I start on the outer bottom endcap. Instead of doing more measuring to find the center of the board, I simply drill the pivot hole from the other endcap (with the test piece of sonotube since that give me the width of the MDF and sonotube) all the way through. Then it's a simple matter to make a mark for the radius to set up the circle jig for routing an endcap that's about 1/4" wider than the sonotube/MDF which will provide a slight ledge for the bottom side.

          Photo 13 : As with my last project, I used a paint stirring stick to make a circle jig extender to make endcap over 24" in width (this endcap will wind up 24.5" in width). This is a close up of how I did the extension. I had to drill 2 small holes through the steel piece of the circle jig pivot arm to hold 2 small nails (this keeps the paint stirring stick aligned with the rest of the jig. Then I drill a 1/8" hole for a larger nail to be used as the pivot, and insert a 1/8" thick nail as the pivot. I also had to drill a hole in the paint stirring stick for the circle jig original pivot piece.

          Photo 14 : This gives you an idea of how the circle jig extender looks in operation (I was able to flatten out the angle a little more when I'm routing so the sides are cut pretty straight and not at an angle).

          Photo 15 : I used 2 passes to route through the MDF boards, and this shows me starting through the 2nd routing pass, as I get done with the outer bottom endcap.

          Photo 16 : Using the same technique for finding the center hole for the outer top endcap as described above, I place the endcap/sonotube test piece, and then I align it so I have enough material to make a 1.5" overhang for the outer top endcap (you can see the marks I made for my router radius reference length).

          Photo 17 : I start routing the outer top endcap, employing the 2-pass routing method (makes for less stress on the router/bit).

          Photo 18 : The outer top endcap is finally routed completely.

          Photo 19 : Yes, another shot of me in my sawdust gear, always remember to wear safety glasses, ear plugs, and a nose/mouth mask because breathing MDF sawdust is no fun.

          Photo 20 : Using my bottom piece from Sunosub II, here is a quasi-isometric view of what Sunosub III will look like when it's finished (pre-paint/fabric covering).

          Photo 21 : This is a side view of what Sunosub III will look like.

          Photo 22 : Here's a shot of all 4 endcaps, stacked in a way to show the differences in width.

          Photo 23 : And another shot of all 4 endcaps side by side one another.

          Now I start on the bottom endcap and the holes needed: driver hole, terminal cup hole, and the port hole (which will have to be done when I receive the flared port since I don't know how wide of a hole to cut into the endcap).

          Photo 24 : Again, using the same idea to find the center for holes/endcaps, I work on the driver hole once I measure out a 14" wide hole. I drill all the way through both endcaps.

          Photo 25 : I route the driver hole on the inner bottom endcap first, and I'm using some excess MDF board underneath to keep the hole from just dropping out, along with the router itself (I only route about 1/2" deep on the first pass, and then flip it over and route the final pass).

          Photo 26 : As you can see, I flip the inner bottom endcap over and successfully routed out the hole for the driver.

          Photo 27 : Next, I keep the same circle jig radius and start cutting out the driver hole on the outer bottom endcap.

          Photo 28 : I flip the endcap over and complete the routing of the driver hole on the outer bottom endcap.

          Photo 29 : Ta-da! Another driver hole is born!

          Photo 30 : I make sure the 2 bottom endcaps align themselves with the new driver hole. I try and make sure the ledge is consistent all around the perimeter for the outer bottom endcap.

          Photo 31 : Just to see how all the bottom endcap accessories will fit, I lay out the terminal cup, the leg mounts, and a 4" port as a place holder for the flared port (just to make sure I have enough real estate on the endcap in the layout).

          Photo 32 : The terminal cup's depth is exactly 3/4" (not including the actual terminal spade connectors) so I all I need to route is the outer bottom endcap, so I sketch in the hole that needs to be routed.

          Photo 33 : I start routing in the terminal cup hole. I set the plunge depth to 3/4" so I don't cut too much of the MDF board underneath, which is used for support, and I clamp down both pieces so the board don't move around.

          Photo 34 : I finish routing a rectangular hole for the terminal cup hole.

          Photo 35 : Here's the piece that I routed out, but I had to do some hole expansion to get the terminal cup to fit snugly, so I did some touch-up routing too.

          Photo 36 : On the inner bottom endcap, I needed to cut in the holes for the terminal spade connectors, so I draw the 2 sets of holes that need to be cut through.

          Photo 37 : I finish cutting in both holes for the 2 sets of terminal connector holes. I do this to maximize the bottom endcap material and reduce air leak possibilities.

          Photo 38 : Here's both pieces of bottom endcaps after the holes for the driver and terminal cup has been cut into them.

          Photo 39 : I laid the bottom endcaps together to see how they fit, and I make lines inside the driver hole so I can line it up consistently later on when I'm glueing the pieces together.

          Photo 40 : Believe it or not, but this is all the sawdust I managed to sweep up afterwards. Whew!

          That's all for today, I was getting tired, and the sun was giving me a redneck burn if I didn't get out of the sun soon.


          What's up next for the coming weeks:

          1. I'll do some sanding of the outer endcaps to smooth them out, and give them minor rounded edges. I can work on the outer top endcap, and give it a piano black finish.

          2. I'll install the inner top endcap (nail it into place and caulk it from the inside), and smooth out the sonotube edges on the top side with the endcap.

          3. Once I get the flared port, I'll cut in the holes for the port on the bottom endcaps, Then I'll glue the bottom endcaps together.

          4. Once the Tempest driver shows up, I'll be able to drill in the driver mounting holes.

          5. Then I'll paint the bottom endcap and do a piano black finish, and then attach the leg mounts to the bottom endcap and attach the flared port and nail in the inner bottom endcap to the sonotube and caulk it from the inside to seal up airleaks.

          6. Then I hook up the driver to the terminal cup connectors, and screw in the driver and the legs (mostly, I'll add roller casters on the legs and still have 6" of clearance on the bottom).

          7. Once that's all done, I'll attach the top endcap cover to the top using dowels so that the top piece is removable.

          8. Roll the Sunosub III into the HT, hook it up, and do some listening to it.

          PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
          PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs


          • Patrick Sun
            Super Senior Member
            • Aug 2000
            • 1380

            Day 3: 9-24-00

            I paint the legs:

            Photo 41 : Using some primer, I start on painting the legs.

            Photo 42 : Since this will be a black sub, the legs are painted black. A clear coat will be applied tomorrow if I have time.

            I prepare the top endcap:

            Photo 43 : It's now time to start on the top endcap cover. Here's a shot of the straight edges that will be smoothed off.

            Photo 44 : Here's a shot of the rounded edge on one side.

            Photo 45 : Here's a shot of both edges rounded over.

            Photo 46 : Now I start to apply a coat of primer.

            Photo 47 : I completely primer the outer cover, plus I also prime the undersides (where it was needed - mainly 2" of the outer circumference) and edges.

            Sonotube preparation and internal top endcap attachment:

            Photo 48 : Now I start on the sonotube preparations by sanding off the little bits of black paint with 80 grit sandpaper.

            Photo 49 : I check for rough edges on the top portion of the sonotube and smooth out what I can.

            Photo 50 : Glue is applied where the endcap edge meets the sonotube sides.

            Photo 51 : I smear the glue on the top 3/4" of the sonotube.

            Photo 52 : I apply glue on the edges of the endcap too.

            Photo 53 : The endcap is put in place (I do the best I can to get it level with no leveller).

            Photo 54 : I start tacking in small nails, and I do this every 2"-3" around the sonotube. This will also keep the endcap in place.

            Photo 55 : This shows all the nails tacked in, and I had to nail them within 0.5" of the end of the sonotube.

            Photo 56 : Next up is the caulking of the inside using silicone caulk that doesn't require a caulk gun (costs more, but worth it to me).

            Photo 57 : I've finished caulking and smearing the caulk into the edge gaps. I also caulk up the pivot hole in the center from the circle jig.

            Photo 58 : Now I will be using wood filler on the internal endcap to fill in the gaps between the edges of the endcap and sonotube.

            Photo 59 : Here I start to sand away the wood filler and the excess sonotube edges.

            Photo 60 : I noticed that I have some slight unevenness to the top internal endcap, so I apply a little more wood filler.

            Photo 61 : And finally, I sand it down to its final flatness/smoothness. This part is now done.

            That's it for today. I'll be working on the top endcap's piano back finish for the most part in the coming week.

            PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
            PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs


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