Custom Trunk Audio Problem

Beemah702 · #1 (**permalink**) 05-27-2002, 10:48 AM

i am a big fan of customs trunk setups, but i have a problem. i bought my 323i wid the non foldable rear seats, and i found out that my trunk ish all metal (wall to wall). One day i decided to put my friends two 10inch subs in my trunk to see how it would sound. to my surprise it sounded ****ty. i only heard and felt vibration, no boom boom. from this i am scared to get a custom setup and afraid that it might sound the same as the time i put my homies subz in my car. i was told to make a hole where the arm rest folds down in the rear and it should sound better, and i should get a bandpass setup wid one 12inch sub. how does this sound? Any input on my situation and what should i do?

BEHMER · #2 (**permalink**) 05-27-2002, 11:29 AM

You could always cut out a few ports in your rear deck. Thats what I did in my E36 then used OEM speker grills to cover up the choped up metal

My seats fold down too for some good beats

Check the pic...

dysphunxion · #3 (**permalink**) 05-27-2002, 12:38 PM

My e36 has non-folding rear seats, we mounted a W7 in a sealed box to the metal behind the seat. It fires throu the center armrest and is totally sealed off from the trunk. LOTS of BOOM!

I also like the fact that it's as far foward in the trunk as possible, keeping my trunk semi-useful and the additional weight closer to the center of the car.

I plan to do the same thing (if possible) to my new M3 when it arrives.

330Ci St.Grey · #4 (**permalink**) 05-27-2002, 02:08 PM

FOR GOODNESS SAKES MAN DON'T CUT THE REAR DECK!

I've heard nothing but horror stories about people doing this. Depending on where you make the cuts, you can affect the structural integrity of the rear deck on the car, and in a BMW this can be (depending on the model, I KNOW it is on an E36 M3) an actual structural brace. Cut it and your body structure will go wobbly on you.

Your best bet is to either get a bandpass box or even a ported box. Aim the ports on the boxes out through the opening for the ski-bag on the rear seat (same as cutting out a space behind the armrest). You will get great sound! You could also build a sealed box with the subs angled towards each other (a 90-degree angle) with the angle pointed straight at the opening in your back seat. You should be able to see both subs at an angle through the arm-rest opening. That will also give you a good sound, and the benefits of tighter and cleaner (although not as deep) base from a sealed box.

silly 3 · #5 (**permalink**) 05-27-2002, 04:14 PM

Punch out the metal behind the armrest. It is actually only tac-welded in several places. It will just pop out and the cut is clean. Looks like BMW did it. The reason why it is only tac welded into place is so if you wanted the ski bag pass through, the DEaler could easily have it done. However, do not cut the rear deck. Sacrificing the integrity of the vehicle for sound. No way. That's idiotic!

jb330i · #6 (**permalink**) 05-27-2002, 04:29 PM

In my car I had the rubber backing to the rear seats reduced and thin wood placed over. The middle ski rack armrest plate punched out and the whole trunk is dynamated. This helps channel the bass into the car. Bmw's are naturally very insulated. Not a lot of sound comes out of the car. I can honestly only hear it real good when I roll the front windows down. Theese are 2 type r 12" on 2 alpine 1507 1k amps. mids and highs running to a 407 amp. Sounds great. Try different methods.

dysphunxion · #7 (**permalink**) 05-27-2002, 04:40 PM

Who said anything about cutting up the rear deck!!? The hole for my sub is where the rectangular ski hole would have been (never punched out on my car). Even if that flimsy piece of sheet metal WAS vitally important, my sub is actually sandwiching it between the box and itself with a dozen screws making itself sort of a structural brace. It took some work getting it right but I found the toughest part to be modifying my back seat (upholstery).

C'mon guys, give me SOME credit, I am a freakin' engineer!

Okay, ok.....I can see how a jackass with a sawzall can get into trouble. It has to be done with some skill and planning. Yeah some welding was involved, I guess stereo shops won't go that far. I'll stop giving advice now...

The port holes in BEHMER's ride 'could' be trouble.

silly 3 · #8 (**permalink**) 05-27-2002, 05:19 PM

Quote:

Originally posted by dysphunxion
Who said anything about cutting up the rear deck!!?

BEHMER did...

BEHMER · #9 (**permalink**) 05-27-2002, 09:59 PM

Trust me I thought of that...I put the 4" holes in the part of the rear deck that was a thin piece of metal there is still the thick structure part with angled metal and what not on all sides. It is kind of hard to explain but if you saw it in person you would understand that it is not a vital part of metal

and the holes are small but make a big difference in the db level. I could guarantee that I would not have been able to cut through the structural part with my little hack saw. BEHMER

Beemah702 · #10 (**permalink**) 05-28-2002, 12:58 PM

Thanx fellas for the input....anymore would be appreciated.

ernie · #11 (**permalink**) 05-28-2002, 03:40 PM

Quote:

Originally posted by silly 3
Punch out the metal behind the armrest. It is actually only tac-welded in several places. It will just pop out and the cut is clean. Looks like BMW did it. The reason why it is only tac welded into place is so if you wanted the ski bag pass through, the DEaler could easily have it done. However, do not cut the rear deck. Sacrificing the integrity of the vehicle for sound. No way. That's idiotic!

silly 3 is absolutely correct, i did this and ported my previous box through the armrest and it sounded great!

Ernie