Stee-Z Posted January 25, 2012 Report Share Posted January 25, 2012 ~CURRENT PLAN~ Outer dim. 16" high 28" wide 30" deep Port 2.5" high 26.5" wide 26" long Net vol. 4.13 ft.^3 tuning freq. 36.33hz Port area per ft. 16.03 in sq ~The port is across the bottom on this box design~ i have most of my box built, but i decided i wanted more of a lower tuning like my current box at 30 hz. I love the lows. Can someone change the port length for it to be a little lower, aroundish where my current box is tuned to? If possible I would appreciate it very much. Quote (4)DD 9918's (2)DC 10k 8 6.5" focals 2 DD SS4 mid amps Audison Bit One processor Jl-cl-rlc line driver iPad in dash Dual Irragi 320a alts 8 batcaps 4000's Second Skin sound deadened Link to comment Share on other sites More sharing options...
rogue Posted January 25, 2012 Report Share Posted January 25, 2012 (edited) by going that low the port is going to need to be stupid long like 50 inches. so long that the internal volume left over after port displacement will be closer to 3 cubes. i think you will need to think about smaller port area to reach 30hz if you are using the dd sub in your avatar i wouldnt go lower than 36. in car tuning will be lower anyways. what dd says about it http://ddaudio.com/faq/what-to-tune-box-port-to.aspx Edited January 25, 2012 by rogue Quote BMW X5 Stealth Build w/ IPAD BMW 325i Rear Deck Digital Designs Build BMW 325i Car PC Touchscreen Bezel Build Link to comment Share on other sites More sharing options...
rogue Posted January 25, 2012 Report Share Posted January 25, 2012 (edited) oops double post.....damn the forum lags crazy Edited January 25, 2012 by rogue Quote BMW X5 Stealth Build w/ IPAD BMW 325i Rear Deck Digital Designs Build BMW 325i Car PC Touchscreen Bezel Build Link to comment Share on other sites More sharing options...
varietyguy Posted January 25, 2012 Report Share Posted January 25, 2012 need to know what sub(s) your running. I put your dimensions in Torresand your tuned to 34 hz now. If you extend your port to 27 inches you'll drop down to 33.77. But like Rogue said if you keep extending your port to tune lower your going to take away from your net volume. Then your port to net Cu. ft. ratio will be off. Quote 1992 Mazda 323 http://www.stevemead...323-wall-build/ Link to comment Share on other sites More sharing options...
bkolfo4 Posted January 25, 2012 Report Share Posted January 25, 2012 Then your port to net Cu. ft. ratio will be off. Who cares!!! OP - The issue is that as your port becomes longer to lower the tuning, the net volume becomes lower, making the tuning higher than you calculated. Your port has to be even longer than you calculated, which will further lower the net volume and again not give you the tuning you calculated. It is an iterative process (along with a little predicting) to get you where you want to be. In your design, you can only go .75" deeper, then you will have to turn up. I am also confused on your current design - I come up with well over 4.13 cuft net volume. What is your sub and bracing displacement? How thick is the baffle? Using 14.5 x 26.5 x 28.5 = 6.34 cuft Port - 26.5 x 3.25 x 25.25 = 1.26 cuft Leaves 5.1 cuft. Where is that 1 cuft going? Quote 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...
Joe X Posted January 25, 2012 Report Share Posted January 25, 2012 You are tuned lower than your spec, actually is: Vb = 4.777 cu.ft Fb = 33.406117 Hz Change the width of your port to 23 in. Vb = 4.943 cu.ft Fb = 30.8059807 Hz If I go lower will compromise you port area, I am assuming a single 15" sub displacement. With dual 12" will be around 31Hz, if you want a better estimate state what subs you are using. Quote Link to comment Share on other sites More sharing options...
varietyguy Posted January 25, 2012 Report Share Posted January 25, 2012 Then your port to net Cu. ft. ratio will be off. Who cares!!! I think he should. If he has too much port the box could start sounding like crap. And start to decrease spl substantially. Quote 1992 Mazda 323 http://www.stevemead...323-wall-build/ Link to comment Share on other sites More sharing options...
Stee-Z Posted January 26, 2012 Author Report Share Posted January 26, 2012 sorry .. im usuing a 9515 DD strapped to an AQ 2200.. sorry bout that Quote (4)DD 9918's (2)DC 10k 8 6.5" focals 2 DD SS4 mid amps Audison Bit One processor Jl-cl-rlc line driver iPad in dash Dual Irragi 320a alts 8 batcaps 4000's Second Skin sound deadened Link to comment Share on other sites More sharing options...
bkolfo4 Posted January 26, 2012 Report Share Posted January 26, 2012 Then your port to net Cu. ft. ratio will be off. Who cares!!! I think he should. If he has too much port the box could start sounding like crap. And start to decrease spl substantially. You are confused. Quote 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...
fecupe2001 Posted January 26, 2012 Report Share Posted January 26, 2012 sorry .. im usuing a 9515 DD strapped to an AQ 2200.. sorry bout that Why do you want a 30 hz tuning???? that sub can play WAYYYY below tuning frequency, specially on that big ass box, if you still want to tuned it lower, just shrink the port area a little bit, that sub can still play strong as hell with around 55 SQ of port Then your port to net Cu. ft. ratio will be off. Who cares!!! I think he should. If he has too much port the box could start sounding like crap. And start to decrease spl substantially. You are confused. x3!! Quote I´m the SPL Gains topic creator!! wanna get louder?? check this: SPL Gains. Panamenian 2009 & 2010 & 2014 Bass Race 149.9 Champion! 2 15" subs and a 2K wired at 1 ohm, http://www.stevemeadedesigns.com/board/topic/167788-fecupe2001-2-15s-on-a-2k-video-on-page-3/ 8 Massive 15" subs and small power, http://www.stevemeadedesigns.com/board/topic/179296-fecupe2001s-8-15s-4th-order-bandpass-wall/ Link to comment Share on other sites More sharing options...
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