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Enclosure Design & Construction
Sealed vs Ported vs Passive Radiator
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<blockquote data-quote="TaylorFade" data-source="post: 8044635" data-attributes="member: 618111"><p>PR's ARE ports. Essentially. They're just huge and use moving mass instead of a volume of air. You actually calculate the weight of the air in a port the size of your PR's diameter to figure out how much mass you need to add. PR's also unload like a bish below tuning so I suggest tuning them lower than you would a standard port if there's a chance you'll play below that.</p><p></p><p>PR's are kind tricky though. The rule of thumb is at least 1.5-2x cone area or xmax. It's tough to find a PR with double the xmax of our subs, so it's got to be 1.5-2x cone area. Like, a 12" PR for a 10" sub or (2) 10" PR's. Say you use a 12" PR. Well... that's basically a 12" port. Say your 10 needs a 1.5cf box. A 12" port in 1.5 cubes for 30hz needs to be, wait for it.... 218" long. Hello. So... the volume of a 12" port that's 218" long is 14.5 cubic feet. Air weighs ~ .08lbs per cube. .08lbs x 14.5cf is 1.16lbs. That's your moving mass.</p><p></p><p>Or you can use this "quick" formula...</p><p></p><p><img src="http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/f89e063d.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="TaylorFade, post: 8044635, member: 618111"] PR's ARE ports. Essentially. They're just huge and use moving mass instead of a volume of air. You actually calculate the weight of the air in a port the size of your PR's diameter to figure out how much mass you need to add. PR's also unload like a bish below tuning so I suggest tuning them lower than you would a standard port if there's a chance you'll play below that. PR's are kind tricky though. The rule of thumb is at least 1.5-2x cone area or xmax. It's tough to find a PR with double the xmax of our subs, so it's got to be 1.5-2x cone area. Like, a 12" PR for a 10" sub or (2) 10" PR's. Say you use a 12" PR. Well... that's basically a 12" port. Say your 10 needs a 1.5cf box. A 12" port in 1.5 cubes for 30hz needs to be, wait for it.... 218" long. Hello. So... the volume of a 12" port that's 218" long is 14.5 cubic feet. Air weighs ~ .08lbs per cube. .08lbs x 14.5cf is 1.16lbs. That's your moving mass. Or you can use this "quick" formula... [IMG]http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/f89e063d.jpg[/IMG] [/QUOTE]
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