How well will a rear facing, rear firing enclosure work in an E30 trunk?

[kawana]

I have an enclosure design done for a rear facing, rear firing ported enclosure, but im just wondering how it will sound in an E30 trunk. Im going to remove the rear speakers and open the holes up, but should I make a top firing enclosure instead? Or will the rear firing design work fine?

[Farbin Kaiber]

Look at the luke box, like the luke box, buy the luke box...

http://r3vlimited.com/board/showthread.php?t=159371

[kawana]

wtf is a luke box? Wanna put a link or something...

[Farbin Kaiber]

Huh?

[kawana]

what. is. a. luke. box?

[Farbin Kaiber]

Reading comprehension owns you?

[kawana]

oh haha, my bad. Link didn't show up the first time. Sorry mate.

[kawana]

Ok, so it fires through the ski hole right? I dont think my '90 325i has one of those openings. There is no fold down section on the rear seat.

[Farbin Kaiber]

It's ok. I thought maybe you were a bit slow, so I gave you the benefit of the doubt.

For serious, Luke is the resident audio guy, and has a really good design, and everyone swears by it. No use in reinventing the wheel.

Go search some of StereoInstaller1's threads, and you will see how it all works...

[318Joe]

Ok, so it fires through the ski hole right? I dont think my '90 325i has one of those openings. There is no fold down section on the rear seat.

BMW built the cars with the ski pass-through pre-cut in the rear bulkhead. Only takes a couple of good knocks with a hammer to punch the sheet metal plug out. Remove the rear seat or the bulkhead cover in the trunk to get to it.
There is a cloth insulating pad over the rear bulkhead behind the rear seat. Just cut out a hole in the pad where the ski-pass though is and you are done.

Rear seat with armrest optional. Sub fires into the cabin, box is only 4" deep at top.

[kawana]

BMW built the cars with the ski pass-through pre-cut in the rear bulkhead. Only takes a couple of good knocks with a hammer to punch the sheet metal plug out. Remove the rear seat or the bulkhead cover in the trunk to get to it.
There is a cloth insulating pad over the rear bulkhead behind the rear seat. Just cut out a hole in the pad where the ski-pass though is and you are done.

Rear seat with armrest optional.

Really? Isn't the rear seat gunna muffle the sound too much?

[StereoInstaller1]

Damn canandians anyway!

Sheesh!

I shot you a PM about the design and stuff. One of your neighbors solved the shipping issue.

luke

[318Joe]

Not too much. Certainly it will be louder than just having the sub firing into the trunk.

[SoEm0]

I would not use that sort of set up. You can rear fire the sub but i would port through the back dash this will allow for the sound deflection off the back glass. firing it back with the port back will cause all the sound to be lost inside the trunk and out back.

[StereoInstaller1]

I would not use that sort of set up. You can rear fire the sub but i would port through the back dash this will allow for the sound deflection off the back glass. firing it back with the port back will cause all the sound to be lost inside the trunk and out back.

No, bad physics.

In fact, since ports work 180 degrees out of phase with the woofer and you are suggesting putting them 90 degrees out of phase physically with that, you would lose virtually all of your output anywhere near the crossover point from woofer to port...so typically, right around 40Hz you would have a HUGE suckout and would have virtually no power handling from about 35Hz to about 60Hz.

Ports should always be on the same plane as the woofer whenever possible.

Now, keep in mind when firing a woofer rearward, you gain 3db to 6db from "corner loading" the back wall of the trunk, but that output will be filtered at whatever frequency the loading is most present at (the "Q" of the loading is about 1.6 for the few on here who have a clue what I am talking about)...which in the case of the E30, is about 80Hz...so you get huge stupid BOOM at low frequencies (like under 50Hz) and all of the trunk rattles, license plate rattles, the goddamn flappers on the side of the trunk rattle, all of that crap AND you lose every damn bit of your midbass...which is in short supply already in the E30.

So, it comes down to this: if you want giant boom, do 2 or 3 or 4 woofers firing backwards, ported.

If you want clean detailed good sounding bass, use 1 woofer sealed 100% into the cabin, ported or sealed.

Getting all of the bass into the cabin is my main goal.