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Cerberus Subwoofer Build

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  • #16
    Re: Cerebus Subwoofer Build

    Randall,
    I just used a rattle can on the port tubing. It's Rustoleum's "Professional" line, and it actually does a good job on small pieces. I was painting the inside of the port so it would be black when viewed from the outside of the finished enclosure when I thought I might as well paint the outside too. A complete waste of time I'm sure, but I didn't like the looks of the long port with PVC elbows. Even though it would be inside and out of sight it looks like something from underneath your floor, or inside a wall.

    I'm using a table saw to make the rabbets. I've got a vertical fence jig I made for making the cuts with the panel in the vertical position. I didn't bother switching over to the dado blade, so two cuts are necessary. I manage to get sufficient accuracy for a project like this. I know you don't need a photo to understand what I'm talking about here, but for the benefit of anyone I may have confused, I'll insert a one here taken by Mark65 during another project we've got going.



    Regarding the room where I'll use the Cerberus, I have a smallish office about 13 X 13 where I'll use it with whatever speakers I'm listening to, for music. Currently, I'm using it with a pair of Paul's Overnight Sensations and it does a great job. It doesn't produce as much punch as the 12" Dayton subwoofer I made, but it makes more than enough for music played at reasonable levels, and it's about 1/4 the size of the 12" Dayton.

    Ron
    Last edited by Soundslike; 04-25-2011, 01:18 PM. Reason: Inserted photo
    Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
    Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
    Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
    Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
    Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
    NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

    Comment


    • #17
      Re: Cerebus Subwoofer Build

      I forgot to acknowledge the comments by 50 watt head, and djd. Thanks for the nice words and encouragement.


      I installed the vent inside the box, and it fit as planned in the drafting process, so that it's supported by the bottom and sides. I insulated the box with 1/2" automotive felt carpet padding on both sides and the bottom. There was very little area on the back that could be covered, once the plate amp was installed, so I didn't bother there. I was still concerned that I was using up too much of the little box's volume with the large port and all of the insulation I had added, and to do any good on the back, I would have needed to insulate the cover on the plate amp. So, I opted to leave well enough alone.

      In the photo you can see that the driver was moved to the left, and up in the box, in order to make room for the vent. The vent was positioned to take into account the dimensions of the elbows, and a planned roundover of the terminus.

      What looks like a ring around the PVC, is actually a repaired goof. I made the hole too large for the PVC, and rather than throw the baffle away, I elected to make a disc from MDF, sized to fill the hole. I was careful to place a pivot hole in the center, before cutting it out. After the glue dried, I went back with my router and circle guide and cut the correctly sized hole.



      Here's a view through the cutout for the plate amp. As you can see, I've flush mounted the driver and the plate amp. Pay no attention to the little notch, that will soon be gone.:o

      I used a bushing for routing the recess for the plate amp. The easiest method I've found to make this cut is to clamp straight edges for the bushing to follow. It's also necessary to clamp on stops to avoid going to far, and it's important to use a bit with a radius that matches the rounded corners of the plate amp face. To get a bushing with a hole large enough to not interfere with the bit I used, yet shallow enough to for the overall length of the bit, I ended up modifying one. I'll include a longer explanation and a photo, or drawing later, for those who aren't familiar with the process.



      Here's a view with the plate amp in place.

      Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
      Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
      Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
      Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
      Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
      NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

      Comment


      • #18
        Re: Cerberus Subwoofer Build

        nice work on the flush mount.

        button this thing up so we can see some finished photo's.

        Comment


        • #19
          Re: Cerberus Subwoofer Build

          After devoting most of my time to several other build strings, I'm back to the Cerberus. Picking up where I left off - the front two side corners were rounded off, using a 1/2" bit. All other edges were left square, but rounded off softly with light sanding. Earlier, I purchased a 1" roundover cutter for my shaper, planning to use it on this build. But the decision to go with the larger port, made it necessary to move things around, and the necessary real estate was lost. I perhaps could have used a larger radius, but that would mean getting fairly close to the port flare, and I was concerned that it would look odd.

          This next photo, is actually another Cerberus I'm building, but it illustrates how things looked after a 70/30 mixture of fiberglass resin and acetone was brushed on (70% resin). The 70% mix tends to leave brush marks that must be sanded out before paint can be applied, and the resin does take several days to cure thoroughly, before it can be sanded without excessive clogging of the sandpaper. The enclosure shown in the photo was coated with a 50/50 mix, which flows out much better, leaving minimal brush strokes. The enclosure in the photo uses the standard 1-1/2" port and the driver is centered.

          I like to use resin over the MDF, because it transforms the soft MDF surface into a more durable surface, and it seals very well. The result is a very smooth (after sanding) and relatively tough surface that resists dings much better. It is a messy process, and an extended drying period is necessary.



          In this next photo, we're back to the actual enclosure that is the subject of this build. Here, the enclosure has been sanded smooth -- the resin coat was sanded to 150 grit, fiberglass body filler was used to fill all the little inevitable defects, more sanding, then black lacquer based high-build primer was sprayed on, followed by sanding to 220, and finally 400 grit. The reddish stuff is glazing putty used to fill minor defects. You can see the the port required a little smoothing -- that's the result of two little errors. In an earlier post you can see where I had to add a ring around the port tube because I had mistakenly bored the hole too large. Then, when I glued the tube into the resized hole, I didn't insert it fully to the front edge of the baffle, because I had calculated the port length factoring in the port flare. Not too sure how much it matters, but I believe the port length should be measured from the middle of the flare, so I glued it in set back about 1/4". Unfortunately, the roundover didn't reach the tube, so I was left with a little ugly gap to fill.

          To make smoothing the port on the second enclosure easier, I used a different installation process (the one shown in the photo above of the resin coated enclosure with the standard port). On the second enclosure, I first located the port and drilled a 1/8" hole through the baffle so it would be possible to determine where to drill/bore/rout from either side. I then bored the hole with a Forstner bit from the back side, to within 1/4" of the front surface. I epoxied the PVC pipe into the hole, which left it positioned 1/4" behind the surface in order to leave a bit of MDF for the roundover. I added a collar made from 3/4" MDF around the PVC on the backside in order to increase the glue surface area. After everything dried/cured I enlarged the center hole to 1/2", and then used a flush-trim bit to create an extended hole through the MDf that matched the inside of the port. That hole was then rounded over.



          Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
          Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
          Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
          Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
          Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
          NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

          Comment


          • #20
            Re: Cerberus Subwoofer Build

            And folks actually like mdf better than plywood. Never ceases to amaze me. ;)
            I was so much older then, I'm younger than that now.
            OS MTMs http://techtalk.parts-express.com/sh...d.php?t=220388
            Swope TM http://techtalk.parts-express.com/sh...d.php?t=221818
            Econowave and Audio Nirvana AN10 fullrange http://techtalk.parts-express.com/sh...d.php?t=216841
            Imperial Russian Stouts http://techtalk.parts-express.com/sh...=1#post1840444
            LECBOS. http://techtalk.parts-express.com/sh...ghlight=lecbos

            Comment


            • #21
              Re: Cerberus Subwoofer Build

              Originally posted by fastbike1 View Post
              And folks actually like mdf better than plywood. Never ceases to amaze me. ;)
              Yeah, there are lots of things not to like about the stuff. I should give Baltic Birch a go, I guess.
              Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
              Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
              Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
              Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
              Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
              NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

              Comment


              • #22
                Re: Cerberus Subwoofer Build

                After sanding the primer to 400 grit, I sprayed on a single coat of three-part urethane automotive paint. I managed to produce a nice finish, but there are a few areas that could have been done better. Black is difficult to spray outdoors because it's tough to get the light just where you want it so you can view the build up from an angle to get a smooth, even application. For reasons I can't recall at the moment, I elected to finish all six surfaces which, of course, includes the bottom. Not wanting to hang the box for spraying, I used a method recommended in Jewitt's book on spray finishing -- I drilled four holes in a scrap piece of MDF and inserted four 8 penny finish nails to make a support. I sprayed the bottom first, and then set it on the nails while I sprayed the rest of the box. The method works fairly well, but of course you end up with four tiny marks in the paint -- not too big of an issue if it's on the bottom of the box. I also painted the Duellati speakers described in another build string at the same time.



                And here's a photo of the finished subwoofer.

                Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
                Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
                Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
                Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
                Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
                NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

                Comment


                • #23
                  Re: Cerberus Subwoofer Build

                  Thats beautiful............I will be building one of these in the am but my finish will not be as good as that...Great Job on this one..............

                  Comment


                  • #24
                    Re: Cerberus Subwoofer Build

                    If you haven't already done so, check post #85 on this build string. Mikers got an outstanding finish using spray cans and color sanding techniques. On the other hand, subs are often out of sight anyway.
                    Last edited by Soundslike; 06-11-2011, 12:40 PM.
                    Tritrix HT:http://techtalk.parts-express.com/sh...d.php?t=222519
                    Dayton 12" Subwoofer: http://techtalk.parts-express.com/sh...d.php?t=222930
                    Overnight Sensations: http://techtalk.parts-express.com/sh...d.php?t=223751
                    Cerberus sub: http://techtalk.parts-express.com/sh...hlight=cerebus
                    Duellatis: http://techtalk.parts-express.com/sh...d.php?t=224943
                    NTN's: http://techtalk.parts-express.com/sh...d.php?t=227902

                    Comment


                    • #25
                      Re: Cerberus Subwoofer Build

                      More outstanding work, Ron! That finish looks terrific :D

                      Comment

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