what size box do i need?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=80444
Printed Date: July 09, 2025 at 7:45 PM
Topic: what size box do i need?
Posted By: banging35hzs
Subject: what size box do i need?
Date Posted: July 18, 2006 at 4:16 PM
i am planing to put two RE AUDIO MX 12's in a blazer and was wondering what size should the box be? i want it to pass all regulations by DB Drag, IASCA,USACI,MECA, ect,ect. i plant to strat a team with all my friends and are only planing to attend the comps in the VA area. thank you for all yor help.
Replies:
Posted By: jeffchilcott
Date Posted: July 18, 2006 at 4:25 PM
every org has diffrent rules. Also never heard of a MX sub from RE There are the SE SX XXX MT from what I know......
Your biggest thing is going to be below the window line and in the designated "cargo" compartment, if it has rear seats then you have to be behind the rear seats.
That rule will be for usaci and Db Drag. The other orgs you will have the research the rules to find out
USACi will be listed on Soundoff.org
DB drag rules will be at DBDRAG.com
IASCA is Sound Quality except NSPL which is quite small from what I have seen this year
MECA is Drive by SPL, I dont know any of the rules. Sorry
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 19, 2006 at 6:50 AM
well i know that they make a MX 12 because a dealer in my area has them. i might go with the SX 18 instead the only problem is that i have never installed anything lager then a 15 in daily driver set ups, so i dont know what size box would be best for an spl set up and this will be my daily driver car also, the folks at RE say that the SX 18 should have 6.5 cu ft ported after displacment, before is 6.72 cu ft tuned at 32 hzs.
Posted By: jeffchilcott
Date Posted: July 19, 2006 at 6:58 AM
You just might want to double check on that....I just spoke with RE about a week ago and thier product names were not changing. The only thing they had were RE,SE,SX,XXX,MT The MT is an SPL designed only sub. Not for daily driving uses, it has been done but I would not suggest it.
As far as the SX18 I havent heard one in person but I have heard a few XXX18 and it was insane for street use. It was being powered by a memphis 4KW
The recomended box for it is quite large for SPL, but you said you plan to use it on the street...I would recomend making the box so you can change the port to go from street to comp use.
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 19, 2006 at 6:26 PM
well how would i make a box with a changeable port, i have chose to go with the SX18 so forget the mx 12's. i want to break the VA SPL record, which class would this set fall under?
Posted By: banging35hzs
Date Posted: July 19, 2006 at 6:57 PM
go to this link and scroll down till you see RE AUDIO, they only have one vid of the mx 12's https://www.realmofexcursion.com/videos.html
Posted By: jeffchilcott
Date Posted: July 19, 2006 at 7:13 PM
It depends on if you plan to run street beat in usaci, outlaw SPL in USaci (which is classed by amp power at 4 ohm) or db drag
you need to be alot more specific with what you are trying to run in for a class
I dont know the best way to describe how to make an interchangable port system, besides to say recess the port so that it has a 3/4 or 1 1/2 inch lip around the box where you can bolt diffrent ports into
Street beat you can come above the window line and up to the B-pillar.
Outlaw SPL you have to be in the "Cargo compartment" which is behind the rear most seats and under the window line
Street Beat 3 (which is the class the 18 would fall into) has a record of 139.7db This is using a comercially availible cd and a avearage of the SPL using music for a full 30 seconds
Outlaw has scores ranging from 158.5-144.1db with a tone, depending on what voltage you are running and what the rating of you amp/amps are at 4 ohm
More info like what amps you are running and if you plan to run a street beat class or outlaw SPL would help alot
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 19, 2006 at 8:48 PM
is outlaw only able to run @ 4 ohm or can i run a 1 ohm load at lets say 3000watts?
Posted By: banging35hzs
Date Posted: July 20, 2006 at 5:02 PM
just found a new box ive never herd of, whats a transmission line box?
Posted By: jeffchilcott
Date Posted: July 20, 2006 at 10:21 PM
for an Outlaw run, you can run at any impenance you wish, amps are just classified by thier 4 ohm rating, list your amp model and brand and I will look at the spec and list the classes you would fit into.
Street beat you can use as much power you want, but you have to use a commerically availible cd, with music for a averaged 30 second run. Classes are split by sub size.
again list what your complete setup is going to be and I could make some better suggestions
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: aznboi3644
Date Posted: July 21, 2006 at 2:48 AM
Um...transmission line box is pretty hard to design correctly...am I correct?
Posted By: banging35hzs
Date Posted: July 21, 2006 at 7:51 AM
well all of this will be in a blazer or explorer some small but not honda element small suv. i want the SX 18 i might go with boston pro for surrounds as for the amp on the sub i might use a rockford t20001bd or a u.s. amps ax1500de well i want atleast 1500 WATTS, this will have a cap in line with the amp NOT A BATTERY, i know that adding a batt puts me in extreme class i think and as a rookie im not ready for that. i main goal is 150.0-165.0 DB if this can do that then im happy. does any one know the world record for spl, its like 187.5 or sumin right?
Posted By: jeffchilcott
Date Posted: July 21, 2006 at 7:58 AM
I believe you have not been to a show yet. The currnt world record is 181db doing over 150 is extreamly hard, at the last show I judged out of 47 cars only 2 did over 150db
You might want to reconsider your goals before you go out to the lanes
additional battries are fine is Street beat and in Usaci's Stock class.
In Db drag you would be able to only have 2 batteries
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 21, 2006 at 8:18 AM
now as far as transmission boxs i hav a link to a vid of one, https://realmofexcursion.com/videos.html the under RE AUDIO theres only like two so you gatta lokk for them. now as far as building one i never have and dont relly understand them, so i might build on for my boys set and see what happens.
Posted By: jeffchilcott
Date Posted: July 21, 2006 at 8:21 AM
They are tough, but well worth the effort.....all I can say is take your time on it and you will be quite pleased. I will look and see if I can find some of the sites I had when I was building a few boxes like this a few years ago
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 21, 2006 at 8:25 AM
well i have not been to any comps yet other the to meter my boy pioneer 12's at audio express and some guy in a jeep thought he could beat my boy well he lost and we metered 136 at least.
Posted By: jeffchilcott
Date Posted: July 21, 2006 at 8:37 AM
Im just forewarning you, the new metering system used in all comps is the term-lab system. This system uses masurements of pure pressure, vs old meters that took a sampling of audio at 3 given frequencys.
List your local area and I will gladly list some shows in the area, some I might even be judging so I would be more then happy to give you tips and advice on your surrent steup or what you plan to do
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 21, 2006 at 9:02 AM
im in richmond va but am willing to go to any surrounding state. i want to start a team, i wont be competing in any comp untill i get a suv but iam willing to go to learn.
Posted By: jeffchilcott
Date Posted: July 21, 2006 at 6:25 PM
here is the next show in your area.
7/21/2006 5:00:00 PM 1 BRYANT RADIO SUPPLY COLLINSVILLE VA 540-647-3522 FE+CS SP
you can also go to https://www.soundoff.org/cgi-bin/schedule/display.cgi?search=1&display_all=1
to see a full list of shows for the rest of the year.
I know I wont be judging any events that far east but I do make it to KY once and awhile
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 23, 2006 at 8:26 PM
well i had to work, i might go to the spring showdown or the nhra event.
Posted By: banging35hzs
Date Posted: July 24, 2006 at 10:23 AM
i have called all the shops in the Richmond area and they say they haven't done any interchangeable ports and that it would throw off the tuning of the box what should i do?
Posted By: jeffchilcott
Date Posted: July 25, 2006 at 7:48 AM
well your best bet would be to build your own box. I will post some pics of a varible port box later pn today when I can go out and take some
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: haemphyst
Date Posted: July 25, 2006 at 1:22 PM
Anybody mind if I throw something in here?
It sounds to me like you are interested SPECIFICALLY in SPL. If this is indeed the case, forget the transmission line. That is an SQ enclosure, exclusively. Having built several of them, three for the home and one for my '86 Civic, I can tell you with all certainty, you will NOT get SPL from one. They are designed for exceptionally low tuning frequencies, and do not augment the Fs of (pretty much) any SPL designed driver (woofer).
Stick with the vented enclosure.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: banging35hzs
Date Posted: July 26, 2006 at 9:06 AM
well i know i dont want a transmission box because i want a interchagleable port fo a DD/SPL set up, i contacted steve meade to see if he could help on this prob, incase yal dont konw who this is heres his site https://www.stevemeadedesigns.com/ i think yall should chek out the vids anyway
Posted By: jeffchilcott
Date Posted: July 26, 2006 at 6:33 PM
https://www.woodlawncabinetry.com/Resonant_Engineering_Custom_Boxes.html
on this link the picture on the top right side has a stret/smaller port.
on the left you can see where that inner port has been removed from a bigger port.
the smaller port is just sitting on the top of the box for show
Basically you will build your SPL port. then build a smaller port to fit inside that port which is smaller in diameter and longer in length, but it will fit inside the bigger SPL port and will bolt into place.
I hope this helps you out a little, I know Meade has done some interchangable boxes for his tahoe, I know he had one for finals 2 years ago.
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: banging35hzs
Date Posted: July 27, 2006 at 2:11 PM
yea that helps alot, i might send them the specs once i get the sub i want. thanks man
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