View Full Version : Calling Experienced 12" XXXer's

01-28-2004, 11:06 PM
My next install is replacing two Audiobahn AW120Q (http://mainstreet-caraudio.com/car/audiobahn/aw120q.htm) subs in a prefab sealed .88 cu ft (per driver) box in a BMW with a custom blow through box in a BMW E46. The sub will be facing up at the underside of the rear deck (~ 2" away :crazy: ) with two PVC ports through the woofer holes (old woofers going bye-bye) and the ports porting directly into the cabin, facing the rear window (hypothetically... if the mock box sounds like crap, I guess it will be a false wall in the trunk with everything pointing back... but there goes the plexiglass XXX logo cutout :( ) ...

The girl ( :suave: ) I'm doing it for wants it to be noticeably louder than her previous installation, which I believe shouldn’t be hard for a 12" XXX from the numbers I have crunched, but here is my question.

I hear the XXX is a great SQ sub, but I don't know how it handles lower frequencies. RE recommends a 2.1 cuft box tuned to 35Hz for SQL, but I don't think that will be low enough for that boomy rap sound she wants with the low end grunt. I was thinking more along the lines of 30-32Hz, but I have yet to hear one of these XXXs, so I really am kind-of blindly guessing. The box is about 2.71 cubic feet after all displacements with a 32Hz port, but give me your input please!

She always compares it to a kid around here with 2 15" Solobarics in a 8 cuft box in an Ford Expy... and I always say "You've got a coup with one 12"... it will sound good, but it wont shake the windows off of your walls".... still... when she turns it up, she really likes to hear it... :crazy:

Basically, if you've made it this far, and I applaud you if so, is the XXX a low end monster that I can tune relatively high and still get low end grunt, or is it really freaking loud and I can safely tune it low and give her great bottom end with still freaking loud bass?

Argh, I doubt many of you made it through the whole thing... sorry... anyways, back to searching... seems like everyone gets the 15" XXX though... agh...


01-28-2004, 11:35 PM
Make the box bigger and tune it like 28-34hz and it will have all the low end grunt you desire.

01-28-2004, 11:47 PM
Making the box bigger is something I would *like* to do, but the amount of trunkspace I have to work with is very limited. I have to fit an amp under the box and cool it, then fit the box above it with the slant of the BMW's rear deck...... it really cuts down on the space I have to work with... I may just put the amp somewhere else and make it look nice... I'm not sure... but if I do that, how big should I ideally go? Approx 3 cuft? I think that is about the max I can get at this point....

01-29-2004, 12:47 AM
If I were you, I wouldnt hide that amp under the box. You might develp heating problems with the amp and cause it to shut off or even blow. As for the space for the XXX, Id say squeeze as much as you can into the trunk of your vehicle. Mines 3 cubes after all displacments and thats as much space as I could possibly fit. I cant even squeeze an inch out of any side. Id say go out and measure and see what you would be able to fit. Mabye even make a cardboard replica to help you see what you can fit and what you cant.

01-29-2004, 12:47 AM
Question about the slant.

What's the Angle from the floor and back seats?

I'm assuming it's the same angle in both the coupe and sedan.
I have the coupe

Also what's the height of the trunk?

What i am thinking of doing is a

8" RE like this


But Ported! The box will be about 24" long by 16" tall (should fit) with a depth of 12 in. Haven't figured out the volume of the port dimensions. want atleast maybe 27Hz the lowest.

This is why i want to know the slant

ALSO with this will have


12" XXX in the tire well....Thinking bout porting it maybe to 32Hz. Will be taking out the rear deck speakers to allow the 12 to enter the cabin

What do you think about these both? Am i Crazy? Should i do it?
Thinking bout using the 8 for the highs, and 12 for the lows/mids. What Hz do you guys recommend?

Will be using the 36.1 when it comes out to power 12

Not sure yet what to power 8, thinking bout 100.4 and use that also for Focals.

01-29-2004, 01:34 AM

It's sad when you call you car company's center and a LARGE local dealer/service center and they can't provide you with ANY amp ratings or information.

Was wondering if you knew any information about the stock amps in the e46 325?

I would provide you with further info, like a part number but my car is in NYC, and i'm in Rochester at school.

Thanks for anything you can provide

01-29-2004, 07:57 AM
For that info, you guys might want to check out http://forum.e46fanatics.com/ but I calculated the rear seat's angle to be about 70.9°

Thanks for all the info

01-29-2004, 08:42 PM
But still, want opinions on my setup, what u guys think?

01-29-2004, 08:49 PM
I think I measured the max height from the two raised edges in the trunk to the lowest point on the shelf to be 14". I don't know if you can fit a big enough box in the spare compartment without making a false floor, but if you do that, it should sound sweet!

This weekend we are mocking a 3/4" MDF box with 2 3" ports of PVC and just testing the waters, making it as big as possible.... it will probably be about 3 cuft... but I'm started to get really worried about port noise.... I hope it isn't a big issue, but I haven't found any flanges for the ends of the PVC pipe, and nobody around here carries any type of ports! Agh.
I'm also worried about the box fitting in the trunk opening. It is just over 17" wide diagonally, so I hope I can coax it in there... but its like max 35" by 17.5" ... so it will take some work... :eek:

I will update again after the 'mock-box' is done... wish me luck!

01-30-2004, 01:31 AM
Your the man, can u do me one more favor.

I am 500 miles away from mt 325, so was wondering if you could measure the angle for me!!!

I thinkg 14" should be enough for an 8"re. But those raises from what i remember were atleast....4 inches off the actual floor, so like 18 from original floor....which would be like 28 from bottom of tire well.

This setup will be soooo sweet.........

01-30-2004, 01:35 AM
Its not my vehicle, but I will have access to it tomorrow and I will do. I'll try to get detailed geometry of it, because crap... I need it too :)

I'll let you know what I find out....

01-30-2004, 12:23 PM
Great!!!! Your the Bestest MAN!!!

02-01-2004, 01:23 AM
The geometry I posted above is pretty durn accurate...

I didn't get to install today because of rain (always raining in FL... booo)... mabey tomorrow...

I'll keep you posted on new measurements

02-01-2004, 02:54 AM
What about the width of the rear armrest? i'm assuming 8".

02-01-2004, 11:10 AM
By chance do the seats fold down? You could put the box through the door and over the seat.

02-01-2004, 01:17 PM
Unfortunately, the seats do not fold down. I wish they did, but they don't :(

That fact alone means squeezing the box in is going to be difficult... but I like that idea for bimmers with seats that do fold :)

02-01-2004, 02:20 PM
That will work for me!!! :offwall:

What kind of Bmw is it?

02-02-2004, 02:35 AM
2000 328i

New plan as of today:
I have given up on porting through the rear deck, it's too much work, and after playing with my momo in there, it sounded the same facing up/back IMHO.

Our new plan is still sub cone pointed at the rear deck, about 1.5" away, with a slot port right on the floor of the box facing the rear of the car, tuned to 28-30Hz...

Also, I'm going to build from the floor up, not those two ledges, its easier and no amp to deal with... which is giving me approx 3.177 cuft to work with :)

I hope to get the mock box done NEXT weekend, barring weather again... of course...

Will update again, space cadets!