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Silver Member Username: Goose5714Post Number: 515 Registered: Feb-06 | The one thing i still haven't picked up in car audio is how to tune a box lol...don't understand it at all. So i was wondering if someone would help me out...i need some basic plans/designs for a 3.5 ft^3 box tuned to 32 hertz. It has to be exactly 16.5 inches tall.... (this box is for my cousin who i sold my 15 atomic ap/spl too) |
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Gold Member Username: Adam_sPost Number: 1381 Registered: Aug-04 | http://www.subwoofertools.com/forum/ported-box.asp?Ew=30&Eh=16.5&Dia=9&Xmax=16&V d=.2&NumW=1&Vb=3.5&Fb=32&Qts=&Vas=&Fs=&CE=0 Try that. |
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Silver Member Username: TheweaselSteamboat springs, Colorado U.S. of A Post Number: 783 Registered: Mar-06 | that site has never worked for me. it always makes the box's volume too big. that box comes out to about 4.2 cu ft after all displacement try this box 30" wide, 16.5" tall, 17" deep. port is 3" wide and 25" long. |
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Gold Member Username: Adam_sPost Number: 1385 Registered: Aug-04 | That box is actually 3.5 after displacement. I am not sure how you calculated it. |
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Gold Member Username: Adam_sPost Number: 1386 Registered: Aug-04 | That box you suggested is about 3 cuft before sub displacement. |
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Silver Member Username: Tiki89Post Number: 135 Registered: Oct-06 | since when does a sub have .2 for sub displacement lol we need to know the sub displacement for the atomic sub |
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Silver Member Username: TheweaselSteamboat springs, Colorado U.S. of A Post Number: 785 Registered: Mar-06 | http://www.the12volt.com/caraudio/boxcalcs.asp subtract about .3 cu ft for sub displacement and port displacement |
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Gold Member Username: Adam_sPost Number: 1388 Registered: Aug-04 | I didn't know the exact displacement for his sub but .2 is probably pretty close to what it is if you take a look at other 15s and their displacement. |
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Silver Member Username: TheweaselSteamboat springs, Colorado U.S. of A Post Number: 786 Registered: Mar-06 | i tried to use that site for a 4 cu ft box and it ends up being over 6 cu ft http://www.subwoofertools.com/forum/ported-box.asp?Ew=32&Eh=16.5&Dia=6&Xmax=21&V d=.14&NumW=2&Vb=4&Fb=33&Qts=&Vas=&Fs=&CE=0 do the math on a calculator and then divide by 1728. |
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Gold Member Username: Adam_sPost Number: 1389 Registered: Aug-04 | .3 for sub and port displacement?? Port displacement for your box is .65 so how are you getting that? |
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Gold Member Username: Adam_sPost Number: 1390 Registered: Aug-04 | Again after sub and port displacement that box is pretty close to being right on. How are you calculating the port displacement?? I have a feeling it is not right. |
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Silver Member Username: TheweaselSteamboat springs, Colorado U.S. of A Post Number: 787 Registered: Mar-06 | port displacement for mine is .20 plus .28 for subs. 18.5*15*.75= 202.5 cu in 13.25*15*.75=149 cu in 149+202.5= 351.5 cu in 351.5/1728= .203 cu ft |
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Silver Member Username: TheweaselSteamboat springs, Colorado U.S. of A Post Number: 788 Registered: Mar-06 | net box volume 30.5"*15"*25"= 11437.5 cu in 11437.5/1728= 6.62 cu ft before displacement 6.62-.48= 6.14 cu ft |
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Silver Member Username: TheweaselSteamboat springs, Colorado U.S. of A Post Number: 789 Registered: Mar-06 | whoops my bad. i was calculating the port area into the volume. but even then that box is about 4.8 cu ft |
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Gold Member Username: Adam_sPost Number: 1394 Registered: Aug-04 | OK Im gonna use this box for the example and walk you through this because your port displacement is wrong. http://www.subwoofertools.com/forum/ported-box.asp?Ew=32&Eh=16.5&Dia=6&Xmax=21&V d=.14&NumW=2&Vb=4&Fb=33&Qts=&Vas=&Fs=&CE=0 OK first of all you have to account for the wood thickness when calculating volume so the actual numbers you would use for it would be 28.5x15x23.5= 10046.25 10046.25/1728=5.81 cuft before displacement Now on to port displacement. The port area is 75 square inches and the length is 39.25 so 75x39.25=2943.75 2943.75/1728=1.7cuft So 5.81-1.7= 4.11 before sub displacement and you have .14 for the sub displacement so with where I rounded and all that it is about right on. I hope this helps you to understand how it is all calculated out and if you need any help let me know. I aim is steinke8705 if you wanna talk more. |
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Silver Member Username: TheweaselSteamboat springs, Colorado U.S. of A Post Number: 790 Registered: Mar-06 | yep, except i did account for wood thickness. 30.5*15*25 because only two sides are butted. it comes out to about 4.19 cu ft. |
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Gold Member Username: Adam_sPost Number: 1395 Registered: Aug-04 | There is .75 inches of wood on every side so you have to account for it. |
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Silver Member Username: Goose5714Post Number: 516 Registered: Feb-06 | O jeeze i about started a fight lol. Thx guys. |