Shivers Posted November 6, 2010 Report Share Posted November 6, 2010 Hello everyone. I'm using the RE box calculator to design a ported enclosure for my subwoofer. I know I want 29.25 total port length. After entering in all of my other dimensions, I played around with the numbers until I got this: What I dont understand is how a 12.75" piece and a 12" piece make a 29.25" port length. Calculated to inside: 12.75+12=24.75 Calculated to outside: 16+12+.75+2.5=31.25 Averaged: (24.75+31.25)/2=28 Middle of port: 12.75+1.25+12+1.25=27.25 If someone could please explain how this works to me it would be much appreciated. Quote Link to comment Share on other sites More sharing options...
Freshman6969 Posted November 6, 2010 Report Share Posted November 6, 2010 (edited) you mesure it from the middle of the inside of the port like this... http://s748.photobucket.com/albums/xx127/freshman69699/?action=view¤t=newnewbox2-1.jpg dont mind all the random shit i dident feel like croping it Edited November 6, 2010 by Freshman6969 Quote Legal TL scores145.6 on the dash sealed up in the low 40hz area with the port out145.5 on the dash sealed up @30hz with the port inless then 1k clamped on a 3.5k! Why would you EVER WANT flex?huh?...flex is what can make the lows lower and more air being pushed correct? My FeedbackJeep-BuildlogPT LOSER buildlog Link to comment Share on other sites More sharing options...
bkolfo4 Posted November 6, 2010 Report Share Posted November 6, 2010 That calculator is known to make mistakes when calculating L-shape ports. . . 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...
Kranny Posted November 6, 2010 Report Share Posted November 6, 2010 you mesure it from the middle of the inside of the port like this... http://s748.photobucket.com/albums/xx127/freshman69699/?action=view¤t=newnewbox2-1.jpg dont mind all the random shit i dident feel like croping it just for further clarity reasons, this is correct. measure all the way down the middle the port. lets say you have a 4" port. you draw an imaginary line that is 2" from both sides (essentially in the middle) all the way down to the end of the port Quote Link to comment Share on other sites More sharing options...
Shivers Posted November 6, 2010 Author Report Share Posted November 6, 2010 So the RE calculator is wrong? and thanks for the quick replies, shouldnt be too hard to calculate by hand. Quote Link to comment Share on other sites More sharing options...
R_Mac_1 Posted November 6, 2010 Report Share Posted November 6, 2010 Torres box calc is better. His also gives you physical port length which is measured at the port wall so there is no guessing. Quote 2002 Pontiac Bonneville SSEi Pioneer DEH-P6000UB Alpine SPX-17REF 6.5" components (active) Sundown SAX-50.4 Sundown z15 (3 cubes @ 35 hz) Sundown SAX-1200D 2006 Buick Rainier CXL AWD V8 Stock Bose system 12" Alpine Type E in aeroported box Profile AP1000M Link to comment Share on other sites More sharing options...
Shivers Posted November 6, 2010 Author Report Share Posted November 6, 2010 So the physical port length on torres' calculator is the inside measure of the port? on an L port basically the 2 pieces of the L? Quote Link to comment Share on other sites More sharing options...
R_Mac_1 Posted November 7, 2010 Report Share Posted November 7, 2010 (edited) I'm pretty sure it is. That's how I did mine (I also added in the 3/4" for the front baffle thickness). Edited November 7, 2010 by R_Mac_1 Quote 2002 Pontiac Bonneville SSEi Pioneer DEH-P6000UB Alpine SPX-17REF 6.5" components (active) Sundown SAX-50.4 Sundown z15 (3 cubes @ 35 hz) Sundown SAX-1200D 2006 Buick Rainier CXL AWD V8 Stock Bose system 12" Alpine Type E in aeroported box Profile AP1000M Link to comment Share on other sites More sharing options...
kmalinich Posted November 7, 2010 Report Share Posted November 7, 2010 Like this : Here you go Quote Link to comment Share on other sites More sharing options...
Sanitarium Posted November 7, 2010 Report Share Posted November 7, 2010 because it's a bent port the length of the port is actually the average of the LONG side and the SHORT side together. which is the same as the measurement down the MIDDLE of the port. And nice picture, freshman, wonder who made it Quote Link to comment Share on other sites More sharing options...
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