Rogers Posted April 23, 2009 Report Share Posted April 23, 2009 its boggling my mind.... how do you take into account the port displacement in an enclousure when you dont even know how big your port is supposed to be.... so say for instance... in my case.... im doing an enclosure for 4 10" alpine type s's and i need 1 cube net per sub. each sub has a driver displacement of.05cuft, so that would be .2cubes in driver displacement.... i want to do 4 3" round ports..... the box will be subs up ports back...... my max dimensions are.... 23"long X 37"wide X 15"tall.... i want to tune between 35 and 40 hz... i listen to mainly heavy metal and occasional bass testers.... can anybody shed some light on my situation???? this box thing has been stressing me out all night! http://www.stevemeadedesigns.com/board/topic/79921-rogers-700-dream-car-update-page-17-a-wall/?p=2335774 93 Saturn SC2My system4 SA-15's Walled 2 Cerwin-Vega S2000's 3 Kinetik Hc2000's Dual 200amp alts. you guys done with the peepee touching contest or do I need to end it? Link to comment Share on other sites More sharing options...
pstone11 Posted April 23, 2009 Report Share Posted April 23, 2009 well, it sucks, but everytime you get a port drawn up, you have to put it into the total box equation.... The box gross volume always stays the same, but the net volume will change with every port configuration you try + different tuning.... Trial and error at it's best. Check out StoneSounds to see my recent builds.Or look at the Flying White Facebook Page! Link to comment Share on other sites More sharing options...
Ben Building Posted April 23, 2009 Report Share Posted April 23, 2009 The length of your vent (Lv) = 1.463 x 10(to the 7th Power) x Port Radius in Inches ® / Tuned Resonance (Fb) x Volume of Enclosure in Cubic Inches (Vb). Or something like that. Using basic math, you can tune your box to whatever frequency you want (very easily too since you're using round ports). Link to comment Share on other sites More sharing options...
eliassami5 Posted April 23, 2009 Report Share Posted April 23, 2009 for every cubic foot of space in your box you will need 14-16 square inches of port, so if you box is lets say 5 cubic feet then you will need (5x16=80/ 5x14=70, 70-80 square inches). To get 70-80 square inches of port area you will need three 6" ports, or six 4" ports, or a slot port measuring 20"x4", etc. Always make the enclosure about 1.5 cubic feet larger than it should be, so in your case, design a box that is 5.5 cubic feet. That will allow room for port displacement and sub woofer displacement. If its driving you this nuts building a box for your woofers then you are honestly worrying too much about it, build it close enough to specs and it will sound good. Oh and sketchup is your friend when building and testing out sub boxes. Ports are 8.6" long tuned to 35hz Box is 5.71 cubic feet net port displacement is 1.67 cubic feet for all 4 ports combined sub displacement is .2 cubic feet = ~3.84 cubic feet after displacement. The higher you tune the more cubic feet you will end up with 91' Jeep Cherokee - The Heep Just Empty Every Pocket 96' Volvo 960 - The B◘x [sPL_4_U] HiFonics - Alpine Pioneer - Clarion Infinity - Kicker KnuKonceptz Link to comment Share on other sites More sharing options...
Rogers Posted April 23, 2009 Author Report Share Posted April 23, 2009 this crap is so confusing!!!! im not good with programs or math... but im good with my hands...lol.... if someone is bored.... design me a box.... if you can take all my info that i gave in my first post and design it... i can adjust it for bracing... ive actually built a pretty sweet box but its too tall for the car.... after i got it in i noticed that the cones will hit the roof of the trunk... it was a big fail! i just took alpines specs for a vented box right out of the manual and did a 4 in 1 enclosure http://www.stevemeadedesigns.com/board/topic/79921-rogers-700-dream-car-update-page-17-a-wall/?p=2335774 93 Saturn SC2My system4 SA-15's Walled 2 Cerwin-Vega S2000's 3 Kinetik Hc2000's Dual 200amp alts. you guys done with the peepee touching contest or do I need to end it? Link to comment Share on other sites More sharing options...
Rogers Posted April 23, 2009 Author Report Share Posted April 23, 2009 for every cubic foot of space in your box you will need 14-16 square inches of port, so if you box is lets say 5 cubic feet then you will need (5x16=80/ 5x14=70, 70-80 square inches). To get 70-80 square inches of port area you will need three 6" ports, or six 4" ports, or a slot port measuring 20"x4", etc. Always make the enclosure about 1.5 cubic feet larger than it should be, so in your case, design a box that is 5.5 cubic feet. That will allow room for port displacement and sub woofer displacement. If its driving you this nuts building a box for your woofers then you are honestly worrying too much about it, build it close enough to specs and it will sound good. Oh and sketchup is your friend when building and testing out sub boxes. Ports are 8.6" long tuned to 35hz Box is 5.71 cubic feet net port displacement is 1.67 cubic feet for all 4 ports combined sub displacement is .2 cubic feet = ~3.84 cubic feet after displacement. The higher you tune the more cubic feet you will end up with hell yeah.... that is a BIG help.... thats awsome! atleast i have some numbers.... i think i can take it from here..... Thank you so much! do you think i should do some bracing or is it necessary.... the type s's arent super powerfull but i am going to be running 1000wrms through them.... http://www.stevemeadedesigns.com/board/topic/79921-rogers-700-dream-car-update-page-17-a-wall/?p=2335774 93 Saturn SC2My system4 SA-15's Walled 2 Cerwin-Vega S2000's 3 Kinetik Hc2000's Dual 200amp alts. you guys done with the peepee touching contest or do I need to end it? Link to comment Share on other sites More sharing options...
eliassami5 Posted April 23, 2009 Report Share Posted April 23, 2009 yes you should add vertical supports inside the box to help with flexing, also u might want do a double baffle where the subs mount. 91' Jeep Cherokee - The Heep Just Empty Every Pocket 96' Volvo 960 - The B◘x [sPL_4_U] HiFonics - Alpine Pioneer - Clarion Infinity - Kicker KnuKonceptz Link to comment Share on other sites More sharing options...
Rogers Posted April 24, 2009 Author Report Share Posted April 24, 2009 yes you should add vertical supports inside the box to help with flexing, also u might want do a double baffle where the subs mount. how do you suggest that i compensate for the loss of volume due to bracing... just change port length or make the box a tad bigger or what???? would a 21.5 by 6 verticle brace be sufficient enough? http://www.stevemeadedesigns.com/board/topic/79921-rogers-700-dream-car-update-page-17-a-wall/?p=2335774 93 Saturn SC2My system4 SA-15's Walled 2 Cerwin-Vega S2000's 3 Kinetik Hc2000's Dual 200amp alts. you guys done with the peepee touching contest or do I need to end it? Link to comment Share on other sites More sharing options...
BanginOnABudget Posted April 24, 2009 Report Share Posted April 24, 2009 save the money on ur system and buy a better ride man...just IMOO im taking out my passenger seat, battery is disconnected, going to unwire and take out the three amps, take out the 70+ lb box, then the platform so i can crimp 1 wire. Almost as bad as those fegs that put those horns in their grills and roll down the street distorting the block.... 1990 Jeep Cherokee 2 Dr. Big-3 in 0g on Stock Alt. Pioneer 6.5" and 5.25"s temp. until i can afford the new crescendos. Pioneer 6000ub Reciever NO amps at the moment. SA-15 on 1kw coming soon. MSG Me for a free enclosure design!! Flared port kits coming soon!! Link to comment Share on other sites More sharing options...
bkolfo4 Posted April 24, 2009 Report Share Posted April 24, 2009 Why all the guessing and approximations? The easy way - You know what you want your net volume to be. You should know the driver displacement. You know how much port area you need. Calculate the port length based on area (you should know approximate H x W too for a slot port). You now know port displacement. Gross volume = net volume + driver displacement + port displacement. Current system: 1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s Previous systems: 2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz. 1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz. Link to comment Share on other sites More sharing options...
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