Phoenix Gold Phorum

So I have dual 15" Octane R's, had them for about 5 years. My old box was 5 cubic feet, ported. I have a new car, so I'm building a new box. However, I can't locate my specification paper that came with my subs. All I remember is for a sealed box it should be 3 cubic feet. I found a subwoofer calculator online, but it asks for total Qts, and I have no idea what they should be. Any help would be greatly appreciated!

here's a link to the manual
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http://download.phoenixphorum.com/Manua ... ualweb.pdf

Go easy on the power as their tinsel leads are very very weak..