building box for l7's

looking for some suggestions on boxes, for 2 kicker L7 12's   they are dual 2 ohm.     This is going to be for SPL purposes only, if any of you know me you know I wouldnt run L7's on the street. Again SPL only.     I am debating between seperate chambers or a large single chamber for both subs     Right now I am running thoughts of between 5-6cuft total.   This will include the port.    The 5 cu ft will have a port of 5x15x20   giving me a tuning of about 38hz.       I might raise the tuning a little, but the car we are using really likes low tuning for SPL. Again any thoughts or suggestions would be great2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place

Ahhh, the fesy. Low tuning? If i remember right, res freq was in the mid 50s on that. I beleive it got the nickname "Panda" from SPL compeditors. Anyways, i would go for around 5.5 cubes after displacement, do a common chamber box, use aeroports (or VERY smoothed and rounded slot port). Use 3/4" or 1" MDF with a layer or two of fiberglass resin. Dont fear aerodynamic bracing, as it makes the differance between winning and loosing ;) Is this going to be for showing off or competing?04 dodge neon SXT

(2) Oz Audio Matrix Elite 12"s sealed in 4 cube fiberglass enclosure, powered by HiFonics BX1605D

Oz Audio Matrix 180cs 6.5" component set power by HiFonics ZX4000

this is going to be going into the civic for a few shows.    That car seams to like the low frequencys. I was planning on a common chamber around the range you were talking 5-5.5 cu ft     More then likely going to go with a slot port, I will go with your suggestions of rounding the port, I have seen some increases that way, but where gonna test the box before then try again rounded. We are going to go with 2 diffrent box designs.   One with subs and port up, the other with sub up port back.     having alot of trouble getting this car to get to the #'s we want to see2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place

When you say your car likes lower numbers, what frequency are you talking about? Saying 38Hz tuning, im assuming 46-50Hz? How do you know what your car's resonant frequency is? That would be where i would start first. It seems that you may be tunning too low. My neon has two peaks. First is at 48Hz, secondly at around 57Hz. Since it takes less power to play 57Hz, it would be wiser to tune to that. Also, a subwoofer responds MUCH louder when porting higher, so 57Hz would be ideal to produce my resonant frequency. so taken that example, id figure out your next best number and stick with it ;) round the ports the best you can. More and more dBdrag compeditors are finding this out. Its like port+polishing your intake... smooth and no restriction. If you want to get REAL picky and get down to adding a few .1 Hz. fiberglass and do a smooth sand through out the entire box to make it smooth as possible inside so the turbulance is minimal. Just remember, aerodynamics inside the box is the key along with strength. If im to guess which would be loudest in your ford, i would say facing back with ports firing back as well... Im sure you can find a few SPL installs on sounddomain or termpro using your type of car and get some ideas. Hope that helps.04 dodge neon SXT

(2) Oz Audio Matrix Elite 12"s sealed in 4 cube fiberglass enclosure, powered by HiFonics BX1605D

Oz Audio Matrix 180cs 6.5" component set power by HiFonics ZX4000

Again we are not using the ford for this project.      We are using the Civic Coupe.      Yes there are 2 peaks 42hz, and 54hz.      we have tested this numerous times using a 1 cuft sealed box and diffrent subs.      At 54hz we only hit .1db higher.     Yes a gain but not much.      We were tuning to 34-36 hz depending on the sub to hit our 42hz mark.      with these subs it looks as we will be able to tune to about 38 hz to get around our 42hz in cab.    Only time will tell on this one.      Since you use a neon, what way do you fire your subs/ports.      We have fired in before but the car didnt really resond well to that,    and finding that there is a sweet spot that when we back the box up towards the tail lights we can gain about .3db      so the new box will have to be moved back and forth to find the spot. Should be interesting2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place

coupe? There ya go! so a trunk in other words. The best way to hit hard ON THE METER (definatly not to the ears/at the headrest) is to face them foreward and seal it off from the trunk. I, myself, have mine facing upward, in a sealed box as this is my SQ vehicle (until i can afford doing my SPL rig).... www.sounddomain.com/id/nodestiny Why are you trying to hit the lower 42Hz mark? Though with sealed boxes it will show with a .1 dB gain, thats not the point. goto www.linearteam.org and get WinISD. Get your subs programed into there, start a new project, select the sub, select quantity of 2, vented, and it will come up to the main screen. Then, pick home many cubes you have in your box. Tune on box to get its peak at 42Hz. Then, do everything again (start a new project, leave the 42Hz peak box open though) and with the new one, find the peak at 54Hz. Ill bet youll gain a good 3-4Db just by changing over your attemped frequency peak. If the point is just to bump to the meter, go for the higher tuning. Just make sure that when you face the subs and port foreward, SEAL SEAL SEAL from the trunk. Seal off the best you can. There are trunker's hitting in the 150's doing this (of course, with a ton of power, but people with 2 10"s can do it).04 dodge neon SXT

(2) Oz Audio Matrix Elite 12"s sealed in 4 cube fiberglass enclosure, powered by HiFonics BX1605D

Oz Audio Matrix 180cs 6.5" component set power by HiFonics ZX4000

Sure enough, L7s LOVE airspace. Biggest airspace hogs in terms of subwoofers that i have ever seen. The bigger the box you can get, the better. And as i have said, WinISD will help you model the box to get your best peak with whatever airspace you go with.04 dodge neon SXT

(2) Oz Audio Matrix Elite 12"s sealed in 4 cube fiberglass enclosure, powered by HiFonics BX1605D

Oz Audio Matrix 180cs 6.5" component set power by HiFonics ZX4000

thanks steve I will get a chance to look at them tonight.    Its gonna be tricky. we are going to use 2 amps, one per sub.     Nodestiny   I think you underestimate me,    I have used WinISd for years.   The box will be ported, no SQ for these shows.   The reason I am not wanting to raise the tuning frequency is the last 2 sets of subs re ran at a high frequency, 56hz. were both damaged due to the port being so large it almost was operating free air.    Just need to spend alot of time testing and retesting        the show is on the 12th so we still have a few weeks,   thanks for all the help you guys,   let me know if you have any other suggestions2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place