Sanitarium Posted September 28, 2010 Report Share Posted September 28, 2010 Alright So here's the problem. I been toying with the idea of upgrading to 4 18's. I don't want to use a camper shell, i'm restricted to 48"x96"x19.5". Now, fitting 4 18's into that space is tough enough as is but.. with the design i came up with (almost the only option) the box winds up being a badly proportioned 6th order with a HUGE peak around 35 hz (12.8 db in bassbox pro) here's the design for reference. i've tweaked with the numbers since that, just haven't uploaded an updated picture. Basicly i wind up with 2 back chambers at 9.4 cubes before displacement each. With the port being the 24" area b*efore the speakers, tuning them to 30 hz. Ok that's the easy part, sounds like an awesome box. But then the 6th ordering comes into play. The front chamber in this picture is roughly 24 cubes (still not utilizing my full 96" possible length) and even with my cabin port as big as it is, on a 24 cube chamber it's tuned LOW, somewhere around 42 hz. So someone with experience, please give me a clue to what to do here. Do i kill as much of the front chamber as possible to get the tuning up, not caring about the final ratio? Do i leave it as is and have a Low note monster that won't play for shit around 50hz and up? New design? Is a 4th order really efficient enough ? Lots of questions and I don't expect them all to be answered. All advice is appreciated! Link to comment Share on other sites More sharing options...
Sanitarium Posted September 28, 2010 Author Report Share Posted September 28, 2010 Uploaded the new image with updated measurements. Link to comment Share on other sites More sharing options...
newls1 Posted September 29, 2010 Report Share Posted September 29, 2010 someone? I love my staffie So anti FACEBOOK it isn't even funny Link to comment Share on other sites More sharing options...
Sanitarium Posted October 2, 2010 Author Report Share Posted October 2, 2010 someone? I'm just gonna do it and see what happens. final picture, 10 cubes before displament per rear chamber, 16.8 cubes front. 30 hz rear, 65-75 hz front (gonna trim the cabin port down to be as short as possible, even if that means rubber boot starts showing..) Paint idea and a little sketchup hairtrick action. Link to comment Share on other sites More sharing options...
dwright27 Posted October 2, 2010 Report Share Posted October 2, 2010 use 4-8 square inches on the rear, per cube, and 18 - 22 for the front. 2006 F-150 4 DC XL M2 18's Walled Daily Driver XS Power 4 DC 3.5kw Team DC Team S.P.L. Lot of Audio Technix and 1/0 DC Audio Dealer American Bass Dealer XS Power Dealer Audio Technix Dealer Link to comment Share on other sites More sharing options...
zfrerichs Posted October 2, 2010 Report Share Posted October 2, 2010 To much airspace on both sides. The ratio is good. But shirnk the airspace down. And idk how much port you have in the rear chamber. But it should be around 6-8 square inches per cube. Roseville, CA Link to comment Share on other sites More sharing options...
Sanitarium Posted October 3, 2010 Author Report Share Posted October 3, 2010 To much airspace on both sides. The ratio is good. But shirnk the airspace down. And idk how much port you have in the rear chamber. But it should be around 6-8 square inches per cube. ~19.5 cubes for 4 18's is too much? Seemed a little small to me, but then I've only done regular ported. My rear port is 18x12=216 square inches---11 per cube. Again, this seemed a hair on the small side to me, but i couldn't squeeze any more in there. Link to comment Share on other sites More sharing options...
STEvil Posted October 3, 2010 Report Share Posted October 3, 2010 You want to be around maximum sealed for the rear iirc. If your maximum sealed is 2.5 that would put you at 10 cubes. Wouldnt hurt to do 12 probably though. MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..." Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through. Hammerdown... 1% no links to outside websites, business related FB/YT pages allowed. Link to comment Share on other sites More sharing options...
2000LaDe Posted October 3, 2010 Report Share Posted October 3, 2010 You want to be around maximum sealed for the rear iirc. If your maximum sealed is 2.5 that would put you at 10 cubes. Wouldnt hurt to do 12 probably though. its ported u fucking noob Link to comment Share on other sites More sharing options...
lunchbox.inc Posted October 4, 2010 Report Share Posted October 4, 2010 its ported u fucking noob a bit harsh? what do you mean by saying it's ported? when building a 6th order, it's often a good starting point to have the rear chamber that same size as what the manufacturer recommends as the largest sealed size you should go... eg. if the manufacturer recommends 3cf sealed, the rear chamber of your 6th order should be around the 3cf foot mark... this isn't ALWAYS the case, but it's a good place to start... this is what "STEvil" was saying... Link to comment Share on other sites More sharing options...
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