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So I finished building a ported enclosure for an extra mcm 8" I had laying around. I was happy with the result.

So I figured I'd try my hand at building a dual ported subwoofer (6th order bandpas). If anyone has any pointers before I start the build feel free to let me know.

However, the point of this thread is more theoretical than practical since I'm wondering what are the disadvantages of this design when compared to the other subwoofer designs? It seems to have some nice positives yet it is extremely rare to come across such design either in plans or physical form.

SeisTres wrote:what are the disadvantages of this design when compared to the other subwoofer designs?

Model it and you'll see. They're very hard to get right, and tend to have narrow bandwidths.

Bill Fitzmaurice wrote:

SeisTres wrote:what are the disadvantages of this design when compared to the other subwoofer designs?

Model it and you'll see. They're very hard to get right, and tend to have narrow bandwidths.

I thought playing around with curves would be half of the work like it was with ported designs. Damn thing is picky indeed. Not only was I having to measure everything down to the millimeter but I had to calculate the volume of the braces! (turns out they take up .4L, who knew?)

Thankfully (luckily?), it turned out well and I'm just relieved it actually works. But I can completely see how a range 30hz and having to calculate the volume of even the braces doesn't make this a popular, or forgiving, design.

I came across this thread, sorry it's a bit old but couldn't resist a reply. Although I've never built one, I have had some luck on modelling software getting quite good SPL curves.

My standard trick on Hornresp is to first design a bass reflex chamber for the driver until you get a good flat curve with a small hump at tuning. For a 35Hz box, you want Fs/Qts around 80-90 and for 40-45Hz around 100-120. That means an Fs of 40Hz and Qts of 0.33 or Fs of 30Hz and Qts of 0.25. Box volume will be determined by things such as cone mass, motor strength, cone area and Vas so experiment with the software.

I then use one chamber with 150% of the vented box volume but the same tuning, and the other chamber with 50% of the vented box volume and twice the tuning. This usually gives an acceptable range that you can tweak by altering tuning and box volumes slightly.

Make sure to use plenty of port area to minimize port compression.