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<blockquote data-quote="speedracerx" data-source="post: 2748966" data-attributes="member: 564120"><p>Over the last year and a half I&#039;ve built a lot of &quot;test enclosures&quot; for various drivers to learn what &quot;the numbers&quot;&nbsp; actually sound like.&nbsp; I might build 3 boxes for the same sub for three different Q, etc. etc. so I can logically build boxes to peoples various different tastes in music, and comprehend reviews in fine mags like Car Audio. I feel I have a good hold on sealed boxes, the formulas and what specs to look for when shopping for a specific application build.&nbsp; What I haven&#039;t successfully backed up is the increased spl I&#039;m suppose to get when I build very large, multi ported boxes. The tuning for frequency is simple enough, but the couple of &quot;overkill- screw sq for big spl&quot; boxes I&#039;ve built always seem dead in all but an extremely narrow frequency range and not much louder even in its sweet spot.&nbsp; I have had great success with reasonably sized ported (usually rear) home speakers, so I&#039;m wondering if I have been trying TO MUCH port volume ( large diameter, flared multi ports) even though tuned for correct freq. I have never messed much with &quot;air speed&quot; numbers figuring that stuff is just to keep air noise down. ......What happens when ports are to large .........(but not for freq), where am I messed up? Even the two 4 in dia, 11 in. long ports in a 4.5 + net cu ft box (rough numbers) seemed to make a Mojo flat. My 2 12 in Brahmas in half the size sealed box&nbsp; (as the single 15 in Mojo&#039;s ) with same amp at similar impedance, played much louder and the sq was no comparison.</p></blockquote><p></p>

[QUOTE="speedracerx, post: 2748966, member: 564120"] Over the last year and a half I've built a lot of "test enclosures" for various drivers to learn what "the numbers" actually sound like. I might build 3 boxes for the same sub for three different Q, etc. etc. so I can logically build boxes to peoples various different tastes in music, and comprehend reviews in fine mags like Car Audio. I feel I have a good hold on sealed boxes, the formulas and what specs to look for when shopping for a specific application build. What I haven't successfully backed up is the increased spl I'm suppose to get when I build very large, multi ported boxes. The tuning for frequency is simple enough, but the couple of "overkill- screw sq for big spl" boxes I've built always seem dead in all but an extremely narrow frequency range and not much louder even in its sweet spot. I have had great success with reasonably sized ported (usually rear) home speakers, so I'm wondering if I have been trying TO MUCH port volume ( large diameter, flared multi ports) even though tuned for correct freq. I have never messed much with "air speed" numbers figuring that stuff is just to keep air noise down. ......What happens when ports are to large .........(but not for freq), where am I messed up? Even the two 4 in dia, 11 in. long ports in a 4.5 + net cu ft box (rough numbers) seemed to make a Mojo flat. My 2 12 in Brahmas in half the size sealed box (as the single 15 in Mojo's ) with same amp at similar impedance, played much louder and the sq was no comparison. [/QUOTE]

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