inputs.text: perfect subwoofer good - sub woofers good provided put correct box bought 2 cheap put 1 huge box 89 cubic feet sealed awful disaster bass poor provided low humming ruined music movies no value whatsoever knew box big gave let 2 sub woofers sit 6 years dug subs storage decided get right built 30 40 speaker boxes knew couldnt throw away 18s without trying better box tried find specifications sub woofers everywhere cant find specs even wrote pyramid made no attempt contact instead take \\average\\ specs similar 18\\ sub woofers could find made box based built box tuned peak 3550hz sounds loud linear compared large 89 cubic foot box new box 358 cubic feet ported sounds 10 times better old box wondering sub work well yes use right box size correct port length first started building boxes didnt know port length would affect sound tune box use online calculator cannot guess spent 4 hours building box going give specs sounds amazing cannot hear port whistling cannot hear distortion sub woofer barely appears move producing intense bass love sub specs box built works perfect linear loud bass piss pyramid not providing specs box area 265\\ x 1225\\ x 2250\\ 7304 sqin divided 1728 inches 1 cubic foot 422 cuft area not including port area port area inside 14 x 3 x 12 029 cubic feet port area outside 155 x 4 x 12 0430 cubic feet box area including port area 422 0430 378 cuft not including speaker driver displacement 020 cuft estimate actual box volume 358 cuft tuning 355 hz 1275\\ long \\slot port\\ port critical part want port least 12\\ long port 3\\ x 14\\ wide x 12\\ long however mounted inside box adds additional 34\\ inch port makes 1275\\ 422 cubic foot box 358 useable ported box im getting sound not much different 2 sealed 10\\ sub woofers 18\\ pyramid roughly twice loud power level truly amazing finally someone posted specs build box know 100 certainty work subs bargain dont worry work not ive never blown sub woofer one fall apart bad glue 15 years old build box right described cannot blow sub woofer not move yes thats correct resonance ported box peak volume occurs sub woofer moves least amount sealed box actually peak excursion peak volume ported box sub woofer hardly ever move wont bottoming ruining therefore cannot blow unless strange reason overpower damn near impossible experience sub need tiny 200 watt amplifier dont let size fool still incredibly efficient louder 2 10\\ sub woofers tested using amplifier dont need anywhere close 1000 watts unless afford tiny sub woofer amp suffice good luck hope helps still got another one sub woofers new box im gonna using long time [ ]