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<blockquote data-quote="Seraphim38" data-source="post: 8418285" data-attributes="member: 638571">For aero ports, you want 7 to 9 cubic inches of port area per cubic foot of net internal enclosure space.&nbsp; Generally speaking.&nbsp; As an example, for the Sundown Nightshade Series suggests 60 cubic inches in a 4.25 cubic foot box.&nbsp; Those have a lot of excursion, which is a factor in port design.A single 6&quot; aero port that is 9 inches long in a 5 cubic foot box will tune you to 34 Hz, and will have a port area of 28 inches of port area.&nbsp; That is a little on the low side for port areaTwo 4&quot; aero ports just under 9 inches long will net you 25 inches of port area.&nbsp; That is even lower.It is too bad that no one I know off the top of my head offers 5&quot; aero ports because that would get you there.&nbsp; But I digress.Three 4&quot; aero ports 16 inches long would get you to 38 inches of port area, which is much better, but those are long ports that would definitely require internal bracing.&nbsp; Parts Express offers a standard 4&quot; that is a max of 17&quot; long.Two 6&quot; ports would have to be 28 inches in length each!&nbsp; Yikes.A single 8&quot; aeroport would need to be 21 inches long to get you to your target tuning frequency.&nbsp; Port area of 50 inches3 is good, but that port would be too long for most designs.&nbsp; I am not even going to run the calcs for 2 8&quot; ports.Conclusion: easiest path is a single 6&quot; aeroport 9&quot; long.&nbsp; Probably the best performing path might be three 4&quot; aero ports 16 inches long.checkit.&nbsp; <a href="http://www.bcae1.com/spboxnew2.htm" target="_blank">Speaker Enclosure Volume Calculator</a>For that big of a box, I strongly encourage you to do some form of internal bracing and add some polyfill.&nbsp; Best performance will be achieved with the ports firing the same direction as the driver.</blockquote>

[QUOTE="Seraphim38, post: 8418285, member: 638571"] For aero ports, you want 7 to 9 cubic inches of port area per cubic foot of net internal enclosure space. Generally speaking. As an example, for the Sundown Nightshade Series suggests 60 cubic inches in a 4.25 cubic foot box. Those have a lot of excursion, which is a factor in port design. A single 6" aero port that is 9 inches long in a 5 cubic foot box will tune you to 34 Hz, and will have a port area of 28 inches of port area. That is a little on the low side for port area Two 4" aero ports just under 9 inches long will net you 25 inches of port area. That is even lower. It is too bad that no one I know off the top of my head offers 5" aero ports because that would get you there. But I digress. Three 4" aero ports 16 inches long would get you to 38 inches of port area, which is much better, but those are long ports that would definitely require internal bracing. Parts Express offers a standard 4" that is a max of 17" long. Two 6" ports would have to be 28 inches in length each! Yikes. A single 8" aeroport would need to be 21 inches long to get you to your target tuning frequency. Port area of 50 inches3 is good, but that port would be too long for most designs. I am not even going to run the calcs for 2 8" ports. Conclusion: easiest path is a single 6" aeroport 9" long. Probably the best performing path might be three 4" aero ports 16 inches long. checkit. [URL="http://www.bcae1.com/spboxnew2.htm"]Speaker Enclosure Volume Calculator[/URL] For that big of a box, I strongly encourage you to do some form of internal bracing and add some polyfill. Best performance will be achieved with the ports firing the same direction as the driver. [/QUOTE]

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