pervitizm Posted June 15, 2008 Report Share Posted June 15, 2008 So I've been struggling with comming up for a design for my subs for about a month now. Everytime I think I've got it, I plug in the number and I'm off by a long shot. My goal is to try and build a box for 2 LvL 4 18's tuned between 30 - 36hz. So if I fall within any of those numbers within that range them I'm good to go. As some of you know I'm been posting everywhere as well as PM'ing a lot of you guys here for advise and what not. This lastest box that I did in sketchup is going to be the one that I'll more than like build for my truck. I just want to make sure my tuning is right. Now when I did the number today I came up with a tuning of 34.3hz, yet when I plug those number into Amatt85's Box Calc spread-sheet I get a tuning of 29.44hz. Now I'm confussed all over again. Now this box still falls under my external measurement of 24Height x 49Width x 26Dept, and I found out that the DC's take about 0.25f^3 of displacement. Internal numbers are as follows: 21Height x 47.5Width x24.5Dept. Throw in the 1.5 divider board in the middle of the box and I get around 6.85f^3 of space. that's of course not factoring in all the other stuff. When I factor in the displacement of the subs ports and the pair of 45's that I'll use for the box I come up with a final number of 5.11f^3 per chamber. I then plug the following fomula into good ole google and I get Fb =0.159*sqrt(84(1.84*100000000) / (5.114*1728(30 + 0.823*sqrt(84)))) which comes out to 34.3hz. So my question is, who'se right? Me with google's help, or Amatt85's Box Calc spreadsheet? Take a look: Quote 2007 Chevy Suburban LT1 Pioneer AVH 5700 DVD Diamond Audio D3 6 1/2 components Kicker 06ZX650.4 amp Kicker 06ZX2500.1 (x 2) DC Sound Lab Level 4 18's with Level 5 coils Autotek Mean Machine 400.1D (replaced) Soon to come: rims body kit flow master pipes Confuscious say "he who say it can't be done shouldn't be bothering man busy doing it" Now feel free to go crawl back under that rock and leave this to the professionals.... Link to comment Share on other sites More sharing options...
jdmbb95 Posted June 15, 2008 Report Share Posted June 15, 2008 (edited) you need to put 49"in the width under (the box outer dimensions) also you need to change the (slot port dimension height) to 22.5" instead of 21" in Amatt85's box calc spreadsheet thats the things i see wrong. the lvl 4 18's on dc site say cubes should be suggested ported 5.75³ ft suggested SPL ported 8³ ft the box design looks good Edited June 15, 2008 by jdmbb95 Quote Link to comment Share on other sites More sharing options...
may03LT Posted June 15, 2008 Report Share Posted June 15, 2008 Any reason you are doing dual chamber/ dual port? Quote Link to comment Share on other sites More sharing options...
pervitizm Posted June 15, 2008 Author Report Share Posted June 15, 2008 Any reason you are doing dual chamber/ dual port? My reason was for some additial bracing besides just the double top and bottom boards and sub stibility. I've floated around with a common chamberd box as well. But right now I think this is more of what I'm gonna go with. Trust me, I've got at least two other threads on this same issue in SMD and multiply box designs floating around out there. Quote 2007 Chevy Suburban LT1 Pioneer AVH 5700 DVD Diamond Audio D3 6 1/2 components Kicker 06ZX650.4 amp Kicker 06ZX2500.1 (x 2) DC Sound Lab Level 4 18's with Level 5 coils Autotek Mean Machine 400.1D (replaced) Soon to come: rims body kit flow master pipes Confuscious say "he who say it can't be done shouldn't be bothering man busy doing it" Now feel free to go crawl back under that rock and leave this to the professionals.... Link to comment Share on other sites More sharing options...
pervitizm Posted June 15, 2008 Author Report Share Posted June 15, 2008 you need to put 49"in the width under (the box outer dimensions) also you need to change the (slot port dimension height) to 22.5" instead of 21" in Amatt85's box calc spreadsheet thats the things i see wrong.the lvl 4 18's on dc site say cubes should be suggested ported 5.75³ ft suggested SPL ported 8³ ft the box design looks good LOL...sorry about that. It was like 3 something in the morning when I posted the box calc picture. Here is another screen with all the correct number plotted in and still I'm showing 21.02Hz from Amatt's deal, while my own number show right at around 34Hz. Quote 2007 Chevy Suburban LT1 Pioneer AVH 5700 DVD Diamond Audio D3 6 1/2 components Kicker 06ZX650.4 amp Kicker 06ZX2500.1 (x 2) DC Sound Lab Level 4 18's with Level 5 coils Autotek Mean Machine 400.1D (replaced) Soon to come: rims body kit flow master pipes Confuscious say "he who say it can't be done shouldn't be bothering man busy doing it" Now feel free to go crawl back under that rock and leave this to the professionals.... Link to comment Share on other sites More sharing options...
Torres Posted June 15, 2008 Report Share Posted June 15, 2008 (edited) with those dimensions, with my calc (it's similar to amatt's, but i got it from somewhere else) i also came up with 21 hz for tuning. BUT...if it's a separate chamber box, the length should not be the full length of the box. it should be for the chamber that you are tuning. so... change the length of the box to 24.5, and i come up with a tuning of 35.26 hz. also...that gives each chamber 4.7 cubes of air after displacement Edited June 15, 2008 by ExpoSport Quote Link to comment Share on other sites More sharing options...
AI James Posted June 15, 2008 Report Share Posted June 15, 2008 imo the double bottom is a waste of wood, as well as the double middle devider. Its not going to displace enough force to flex 1 board in the middle. Quote Link to comment Share on other sites More sharing options...
pervitizm Posted June 15, 2008 Author Report Share Posted June 15, 2008 with those dimensions, with my calc (it's similar to amatt's, but i got it from somewhere else) i also came up with 21 hz for tuning. BUT...if it's a separate chamber box, the length should not be the full length of the box. it should be for the chamber that you are tuning. so... change the length of the box to 24.5, and i come up with a tuning of 35.26 hz.also...that gives each chamber 4.7 cubes of air after displacement ExpoSport, how did you come up with 4.7 cubes of air space? My numbers are showing 5.1 with the 31 inch long port? I also redid the numbers again this time calcuation each chamber as appose to the whole enclosure and this is what I got this time: Quote 2007 Chevy Suburban LT1 Pioneer AVH 5700 DVD Diamond Audio D3 6 1/2 components Kicker 06ZX650.4 amp Kicker 06ZX2500.1 (x 2) DC Sound Lab Level 4 18's with Level 5 coils Autotek Mean Machine 400.1D (replaced) Soon to come: rims body kit flow master pipes Confuscious say "he who say it can't be done shouldn't be bothering man busy doing it" Now feel free to go crawl back under that rock and leave this to the professionals.... Link to comment Share on other sites More sharing options...
Torres Posted June 15, 2008 Report Share Posted June 15, 2008 (edited) eh...each calculator is a little different. lemme punch in the numbers again really quick EDIT: changed sub displacement from .4 to .2, everything else is the same. still came up with 34 hz, and 4.9 cubes of air. still pretty close. at least you're on the right track now compared to 21 hz tuning Edited June 15, 2008 by ExpoSport Quote Link to comment Share on other sites More sharing options...
andym85 Posted June 15, 2008 Report Share Posted June 15, 2008 (edited) here is what i get...5.01cubes, 34.22hz Edited June 15, 2008 by amatt85 Quote i likes me some audio stuff... Link to comment Share on other sites More sharing options...
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