How should I design ports for this subwoofer?

Asked by pikipupiba (1629

) March 23rd, 2010

Here is the subwoofer. It is usually set up so that the driver faces downwards. The ports will go on the front of it (where the two speakers sitting on it are). I want two ports for aesthetic reasons and I have seen other speakers with multiple ports in professional systems.

Here are my questions:

Are two ports better than one?

How big, how long, what material?

Can I make each port differently, thus giving them different tuning frequencies and thus improving performance somehow?

Should I even make it ported? It’s pretty loud now, but it dies off quickly in outdoor venues.

Here are the specs:

18” Woofer, 1000 Watts Peak, 300 Watts RMS, box shape is trapezoidal prism, box volume = 3.252 ft^3

(sorry, no T/S specs)

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4 Answers

ONE MORE THING!!!!!!

Would 4 ports be better than 2? Especially if I can make each one have a different tuning frequency?

pikipupiba (1629

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I love the idea of the 4 port system. I think I’ve discussed before that even though I’ve built a couple of these, my math was approximate or ignored and it worked out fine. I think this lumps me firmly in the super passive amateur category. The potential for differently tuned ports makes sense in my head… although I’m unsure of how the presence of the other ports would impact it.

JeanPaulSartre (5785

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@JeanPaulSartre Exactly! I’ve been trying to work it out in my head how the interference and stuff would work, and this is what I’ve got. A port works by allowing a certain frequency to resonate inside of it, thus amplifying it. So it shouldn’t matter if there are other ports, they will all amplify their own frequency. (I think, I am still researching)

pikipupiba (1629

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That makes sense to me as well… I mean that’s basically how an organ works.

JeanPaulSartre (5785

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