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Huge box problem

 

Silver Member
Username: Sevin7

Post Number: 107
Registered: Apr-05
i got my 2x AW1206t's this week. Opon receiving them i read the owners manual to find out they are not reccomended for use in a sealed box. So i built a ported box to the specifications that audiobahn provied. It said 2.5 cubic foot per a chamber , this included the subs displacement. It also said port size "4x7.25". I ended up making the box about 2.25 cubic feet per a sub (seperate chambers) beucase of size issues, and i kept the port 4x7.25 (im assuming this meant 4inch diameter and 7.25inches long), i made the port out of pvc pipe, one port per each chamber. Now i tested both of these subs out in my freinds prebuilt box he bought, this box was only about 1.75cubic feet per a sub, and we were only running 300rms into each sub. It sounded just as loud as the 2 12 inch Rockford fosgate P3's. But it sounded alot cleaner, i dont know why ppl roast on audiobahn SQ becuase it sounded very clear. Anyways the subs sounded great in his box, we finaly finish making my box, put the subs in, and they sound good, but they are like not even hitting. I'd estimate atleast 10Db less. So just to try things out i throw the subs in a sealed box, and they sound louder in the sealed box than my ported box, even though they are not reccomended to be in it. Any ideas on what i did wrong w/ my box? its all cualked up, no air is leaking, im clueless....
 

Silver Member
Username: Sevin7

Post Number: 109
Registered: Apr-05
i found my problem, the port was only 7 inches long, the box was 14 inches deep. I made ports that were 12 inches long so they were 2 inches from the bottom of the box, and it sounds great. I knowticed on my freinds qlogic box that the port was about 2 inches from the bottom so i did the same to myne. Why did it say make them 4x7 and not tell how deep to make the box?
 

Silver Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 790
Registered: Mar-04
what are the demension of your box?
 

Silver Member
Username: Sevin7

Post Number: 110
Registered: Apr-05
15x15x42
 

Gold Member
Username: Insearchofbass

Post Number: 1959
Registered: Jun-04
well if theres no center divider andthose demensions are external your internal cubic ft is 4.27 cf before displacements...your subs displacement is .25 minus .4 for the port the reason your box didnt sound right at 4 x 7.25 is because you were tuned to 42.5 hz with that box size (which was too high) with 2 inches added to the port your down to about 38.88 hz close to what audiobahn was aiming for in their everyday performer box for that sub which was 38 hz with a 4 inch port 7.25 deep
 

Gold Member
Username: Insearchofbass

Post Number: 1960
Registered: Jun-04
in that box at that tune id bet you hit hard at 45hz to 50 hz depending what kind of car its in
 

Silver Member
Username: Sevin7

Post Number: 118
Registered: Apr-05
i made a center divider, 2 sepearte chambers. How can you tell what the box is ported to? The ports are now 12 inches deep, and the box is 14 inches deep. The subs sound great now but i cut the pipes only 2 inches from the bottom, becuase i knew i could make them shorter if neccessary, should i make them any shorter?
 

Gold Member
Username: Insearchofbass

Post Number: 1964
Registered: Jun-04
ok so the box is 14 inches deep now not 13.5...what wood thickness did you use?
 

Silver Member
Username: Sevin7

Post Number: 122
Registered: Apr-05
well i intended to make it 15x15x42 but in the end things got a little bit screwed up, the wood is 13/16inch thick. I Know that on the inside it is 14 inches deep, i measured that, and i know its 42 inches long on the outside. So its 40 and 3/8 '' long on the inside, minus another 13/16 becuase of the divider in the middle. But how can you tell what the box is tuned to? Also should i leave my pipes @ 12 inches long, or cut some new ones, or make them shorter? I have plenty of pvc pipe.
 

Bronze Member
Username: Adelphia83

Colorado Springs, CO USA

Post Number: 27
Registered: May-05
This is why people rag on Audiobahn. Because joe shmoe has no concept of port tuning, or matching the subwoofers specifications to the enclosure. Everybody hears it and says it sounds like crap. But when done properly, they can be very nice woofers for the price.

You cannot simply use their recommended 4" x 7.25" port, because the enclosure size has changed, which affects port tuning greatly. You want the box to be tuned somewhere around 38 hz.

Depth of the box, and the distance from the back fo the box to the end of the port has absolutely nothing to do with port tuning. It is simply enclosure volume (taking into account the subs presence and the volume of the port you are about to add), and port diameter, and desired tune frequency.

If you enclosure is indeed 4.17 cubic foot, then you are left with about 1.825 cubic foot per chamber (assuming 0.25, and 0.06 for the speakers volume and port volume respectively). With that size the port should be real close to 10" (4 inch diameter) to tune that enclosure to 38hz.

Check out this site for some handy calculators.
http://www.carstereo.com/help/Articles.cfm?id=31
 

Gold Member
Username: Invain

Michigan United States

Post Number: 2401
Registered: Aug-04
Actually, those who aren't your normal "Joe Schmoe's", that try Audiobahn are the one's that dislike the company. Yes, I've even owned an Audiobahn once, and it was in a ported box built very close to Audiobahn specs. Most people that don't know anything about car audio, or those that can't tell good sound quality when they hear it, like Audiobahn. Yeah, it's not the crappiest stuff out there. It's not horrible if you don't have much money and you don't care if the music sounds the greatest.

Those that do know what their doing, and have heard quality systems before would bever think about using Audiobahn.
 

Gold Member
Username: Insearchofbass

Post Number: 1979
Registered: Jun-04
your at about 34.15 hz with a 12 inch deep port per 1.93 cf per chamber which should be about what you have with the divider and such ...id leave the port alone it looks like you have a pretty nice sq box for them
 

Bronze Member
Username: Mr_wiglz

ManchesterEngland

Post Number: 38
Registered: May-05
pretty much most subs can sound good, if the box is built right, its a matter of them sounding great with no distortion at all that tears the $hitty Subs from the good subs. I've had two Audiobahn subs in my car, with the box built to perfect dimensions for each and tuned to 38hz, they sounded good, but not great.

Now I have a DD 9112 sub in my car and I've hit higher numbers, infact I measured it yesterday, properly with a termlab, added my friends yellow top to my system and an xstatic x500 batcap to it also, I managed to hit 154.5db with a single twelve.

previously about two days ago I measured it without any extra addisions in a 2.5cuft box and a normal garage song and hit 149.6db.

Forgot to add, my friend gave me his box which was 4.5cuft thuned to 45hz.

with my two audiobahns I managed to hit 151.2db and that was on the old audiocontrol mics, so if it were on the termlab it would probably be around 147 - 148db.

and I got my DD for less than the two Audiobahns, I paid $300 for a $1000 sub.
 

Bronze Member
Username: Mixneffect

Orangevale, Ca. USA

Post Number: 87
Registered: Apr-05
hahaha i ve never built a box for any of my projects by what the manufacturer specified.

If you want the best Sound Quality you need to use the slide rule. This means you need to do some mathematical formulas. You may use a software program that already has the math calculations done for you as well. But, as far as going by what manufacturers recomend, I would advise anyone to do their own homework. Those specs are so whacked I dont have enough time and space to ellaborate enough.
 

Gold Member
Username: Invain

Michigan United States

Post Number: 2412
Registered: Aug-04
It's usually not the specs on the recommended enclosures that are whacked out, it's the specs of the subs themselves. Ever notice how Audiobahn's are always advertised with rediculous max power ratings, which meen nothing at all anways, along with rediculously large magnets compared to the actualy motor strength. You notice how it's impossible to find the xmax of an Audiobahn sub, or the bl?
 

Silver Member
Username: Sevin7

Post Number: 125
Registered: Apr-05
i thought you guys who calculated the size of the port and tuning the box were genius. Thanks for that link Jeremy Edwards, that makes it alot easier to figure out. I just measured the inside of my box, and it turns out its 13x13x20 per a sub, which is 1.96 Cubic feet. This leaves me with only 1.65 cubic feet after displacment of the port and the sub. And this calculator tells me the port should be 11.29 inches long, its 12 inches long, i guess i got really lucky ... probaly not gonna mess with it, do you guys think i would knowtice any difference if i made the ports .7 inches shorter?
 

Bronze Member
Username: Adelphia83

Colorado Springs, CO USA

Post Number: 30
Registered: May-05
The Xmax specs are all listed on Audiobahns website under Tech Support for every model woofer, as are the theile/small parameters.

When I chose my own enclosures, I did not base it off of Audiobahns specs alone, rather I input the T/S parameters into several different calculators which has suggestions for the optimal enclosure. Even still it was close to the manufacturers recommendations.

The SQ of these subs are excellent for the price paid.
 

Bronze Member
Username: Adelphia83

Colorado Springs, CO USA

Post Number: 31
Registered: May-05
And back on topic, that .7 inches isn't going to make a lot of difference, it's going to tune the box at a lower frequency, which isn't a bad thing as long as the box isn't too far off the recommended size.

A lot of people make the mistake of tuning too low (low must be good, right?), and the sound gets real muddy. But with the size box you are dealing with, I think you're right where you need to be as far as port tuning. I wouldn't change it unless you're not happy with the results.
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