Designer:
GregM

Project Category:
Subwoofers

Project Level:
Beginner

Project Time:
8-20 Hours

Project Cost:
Under $100

Project Description:
I will list a full description here, sorry if it is redundant with other fields below:

I had some ¾ Baltic birch left over from another speaker project, so decided to make a small sub to compliment my small room/computer musical setup. I have the Audioengine A2s. I used the Tang Band W6-1139SIF 6-1/2″ Paper Cone Subwoofer Speaker with the Dayton Audio SA25 25W Subwoofer Plate Amplifier. I built a ported box tuned to 35hz, with dimensions of 9.375 x 14 x 9.75 (in). The port diameter was 2ID x 17.9. The PVC made 2 90 degree bends to allow for ~2.5 inch clearance where the air enters the port, and for the PVC to not hit anything (subwoofer, amp, walls, etc). I stuff some polyfill along the walls between the PVC for dampening but didn’t add too much. Originally the PVC called for about 14.5 inches to be tuned to 35hz, but after considering the displacement of the amp, and subwoofer and the small piece of wood to attach the PVC to, it became slightly longer.
I was inspired by the Cerberus that is all over the DIY forums but I felt I could do better as far as eliminating the chuffing (he used 1.5 diameter vs my 2). I also used a homemade method of flaring the baffle end of the port by basically sanding the opening for what seemed like forever (but I had a lot of time for this project). I used a less powerful amp than for the Cerberus, so perhaps it isn’t pushed as well or as loud, but the results are impressive. I might buy the 70w Dayton plate amp, but I got the 25w one I’m using refurbished for 20 dollars. It isn’t working correctly (cutting on an off randomly) but it allowed me to hear pretty well that this was a good idea to build. I hear chuffing on the loudest volume before distortion on the lowest music/movie content I have. If I back off a bit it is fine.
I finished the outside of the box by counter sinking the 2.5 inch screws, then filling the holes with a mixture of sawdust from my cuts and wood glue. I then sanded these down flush. Then I by sanded the entire box extensively first with an 80, then 150, then 200 grit sandpaper. I then used two cans of primer, with sandings of 200 then 400 grit sandpaper. My last coat of primer was then sanded with 400 grit. I then emptied half a can of flat black on it, then sanded with 800 grit. After that I used an entire can of 2X rustoleum semi gloss on the box. I used 800 grit for the first coat, then none after that. It came out well, not perfect but good. Perhaps for a paint job like that I should’ve used MDF, but I used left over Baltic birch, so it felt free.
I hope this can be an inspiration for others. Perhaps I could’ve flared the port opening more to eliminate chuffing at high volume, but also perhaps the weak amp is making the woofer move too rapidly, maybe subsonic content is causing it, or maybe the 6.5 tang is almost impossible to port without chuffing because a 3 inch diameter port would never work in a box that small. I feel that the tradeoffs for this build are worth it. The 25 watt amp would’ve worked fine, but as I said it’s defective, cutting on an off often. Parts express gave me a refund, so I’m going to likely buy the 70 watt Dayton plate amp soon.

Design Goals:
To make a musical sub with medium output potential for a small 2.1 system used in my bedroom with my laptop, and mp3 players.

Driver Selection:
6.5 inch sub (see parts list)

Crossover Design:
Set in plate amp

Conclusion:
I am very happy with the build, and the results (visually and musically). I think I will put in the dayton 70 watt plate amp soon, and will update afterwards. But the 25w one (when it was working decently) worked well.

About the Designer:
I started making boxes a few years ago for my car and home with 6.5 up to 12 inch subs. Most boxes have been sealed but lately I’ve built ones ported.

Project Parts List:

2X4 foot 3/4 inch Baltic Birch from Home Depot.
2 foot long, 2 inch diameter PVC
2 90 degree bend connector PVC
2.5 inch wood screws.
Wood glue
Caulk
Primer+semi gloss spray paint.
80, 150, 200, 400, and 800 grit sandpaper