[Mpy18]

I am looking to do a 12 inch sub in my trunk. Obviously I need the sub, a box, an amp, and a line out converter. Is there anything else I need, and what are some good brands to work with?

Any and all info is greatly appreciated, don't exactly know much about all of this. Thank you !

[kaigoss69]

Suggest you read the sticky, lots of useful info there...

[Mpy18]

I did ! So many times ! I just still have so many questions after it still.

[mir-ali604]

Good thing you started this thread. Same situation here. Very unsure about a few things especially about which brands to go with.

[kaigoss69]

Subwoofer Locations:

1.) Under Seats.
The enclosures under the seats can be outfitted with specialized aftermarket subwoofers (Earthquake SWS-8) that are capable of decent low-end output. Don’t expect “earth-shaking” bass, but most people seem to be satisfied with the results from this upgrade. The Earthquakes do well with 100 – 150W per channel. They can be run mono, but a stereo signal will give better separation in the mid-bass range. Speaking of mid-bass, these speakers don’t handle this part of the spectrum particularly well. If you’re planning on upgrading to a trunk sub, you’re better off installing dedicated mid-bass speakers in this location.

Example of SWS-8 Installation:



2.) In Trunk.
The trunk itself is a “sealed” enclosure. Think of it as a large metal box sitting in your living room, and then placing the subwoofer enclosure inside of it. It is going to be difficult to get any appreciable output outside the metal box from any subwoofer set-up inside it because the metal box (trunk) is so well insulated from the factory. Thankfully, a phenomenon called cabin gain helps a great deal in amplifying the output of the subwoofer so that it can still get plenty loud inside the passenger cabin of the car. However, there are side effects. The more powerful the subwoofer set-up, the more the trunk panels will want to vibrate. This results in annoying rattles. These rattles can be heard inside the car, but also outside. There may also be a problem with the gas cap spring mechanism becoming damaged from excessive vibrations of the gas cap door.

In order to allow more sound to enter into the cabin, you can open up the ski-hole if your car is equipped with it, or you can fold down the seats, which may not be very practical however.

With the above in mind, there are three different types of trunk set-ups you can choose from:

a) Inside the storage area below trunk floor (not possible in 335 and M3 models). A 8 or 10” subwoofer and a custom enclosure can be fitted into the storage area. The advantage of this set-up is the usage of dead space, and that it is completely invisible. The disadvantage is that the output of the subwoofer is somewhat muffled by the trunk floor lid.

Example of Subwoofer in storage area:



b) A standard subwoofer enclosure placed on the trunk floor. The enclosure itself can be “off the shelf” or a custom-built solution. The subwoofers can be faced toward the back of the trunk, or toward the cabin (results are usually better with the subs facing towards the rear). The disadvantages are the loss of trunk space, and excessive rattles. The advantage is the simplicity and the capability to produce a lot of “bang for your buck”.

Example of standard subwoofer enclosure in trunk:



c) A corner-loaded enclosure. The sub enclosure is “molded” into one of the trunk rear corners using fiberglass. The advantages of this set-up are efficiency and space savings. It hardly takes up any trunk space and the corner-loading effect “amplifies” the output of the single subwoofer to make it significantly louder than the same subwoofer in a standard enclosure. The other welcome side effects of this set-up are that it produces very little rattles and that the bass very easily blends with the front stage. Most sound quality oriented people prefer this type of set-up.

Example of corner-loaded enclosure:



3. Behind Back Seat (Infinite Baffle).
Here we place a subwoofer inside one of the walls of the metal box we call the trunk. The trunk becomes the enclosure. Using the proper subwoofer driver(s), this type of set-up can result in excellent sound quality, while requiring very little amplifier power, and producing the least amount of rattles. A good IB install will require very little EQ to have a relatively flat response between 20 and 100Hz.

Example of infinite baffle (IB) install:




Integration into Stock Audio System:

This assumes that no other audio upgrades are being done and that the subwoofer and amp are the only changes you are making to the stock system.

1. Base Audio:
You will have to tap into the full-range speaker level outputs of the Head Unit. The best place to do this is at the connection for the underseat woofers. The best method of doing it is to use a Technic harness connector as pictured below. No splicing, no cutting, fully reversible:



The signal can then be fed into an aftermarket amp via the high-level (or speaker level) inputs, if so equipped, or through an external LOC (line output converter), which will then give you a low-level signal via RCA for connection to the amp.

You will then need a switched 12V “remote” or “turn-on” signal for the aftermarket amp(s). If you are using an external LOC, make sure you get one with remote out, so you don’t need to worry about getting the remote signal elsewhere. If you don’t have that option, the most appropriate source is pin 13 at the back of the OEM head unit. You will need to run a wire from there to the amp location in the trunk. As an alternate, people have also used the cigarette lighter wiring, as well as the satellite radio fan wiring (which is conveniently located under the trunk floor, if you have it). As always, any splicing of OEM wiring is at your own risk!

2. HiFi & Logic 7:
The HiFi & L7 amps have dedicated, low-passed subwoofer outputs. The amps are located in the rear left corner of the trunk, under the gray plastic cover. You need to tap into these outputs, and feed them into a LOC (line output converter) which will convert the high level signal into low level signal so your aftermarket amp can use it. Some amps have built-in signal converters, but they rarely are designed for the relatively strong outputs of the HiFi, and especially the L7 amps. The last thing you want is damage your amp so always use external LOCs.

If available, always try to use forum member Technic’s add-on harnesses, which make the connections a snap and everything is fully reversible. He uses only the highest-quality LOCs, with built-in remote level outputs.

Technic HiFi Harness:



Technic Logic 7 Harness:

[kaigoss69]

After you read the above, decide what type of enclosure you want. Then start searching/reading a little more because it has all been done before!

[Mpy18]

Thank you very much for all of that ! I am really liking the sub in the storage area under the mat, a regular box type sub and the molded one on the side.

I guess I will look up some DIY on these.

[Denny347]

Ib Ib Ib Ib

[mathematics]

sent you a PM. you're very close to us at Unexpected Creations in Edison, NJ. come talk to us and see my e93. we can talk about your options and you can hear a bunch of products.

Originally Posted by Mpy18

Thank you very much for all of that ! I am really liking the sub in the storage area under the mat, a regular box type sub and the molded one on the side.

I guess I will look up some DIY on these.

[adamroutley]

Anybody have the part number for the Technic Harness needed for the base system and link to an appropriate LOC with a remote cable built in please?

[ctuna]

I think Technic sells it as a kit with everything.

That is both the Harness and the Loc.

As depicted in the pictures above.

[nimo]

Will a corner loaded single 10/12 enclosure sound better than a regular sealed dual 10/12 with same cu. ft chamber as the corner enclosure. Also assuming we are using a sound quality (sq) sub that was designed same chamber specs as the corner enclosure. I wanted to see if any one heard the difference between the single corner vs a normal dual sealed enclosure using sq subs.

I have a dual sealed chamber enclosure running Alpine 12" type E aimed toward the rear. I understand the E90/E92trunk is tightly sealed, so that's why the sound wave is not coming thru. I know the that Alpine type Es are not sq sub, but these subs were sitting in storage for awhile.

I am debating to change out to a corner enclosure. Since I live in Hawaii, it will cost about $1k for the corner enclosure, 10" sq sub, and shipping. Unless any one wants to sell me their corner sub system at a good price.

[nimo]

BTW, I have the OEM hifi system connected to technic harness to JL 600/6 for the OEM speakers and an ALpine MRP-M650 600 watts X1 at 2 ohms to the subs.

[kaigoss69]

I have tried just about everything. Single 12" sealed, dual 12" sealed, single 10" in corner, SWS-8s under seats, single 12" infinite baffle, single 15" IB. Corner loaded will be the most efficient and best sounding in-trunk solution. If it were me, and I had $800 to spend,for the e90 I'd get one of those enclosures from Wicked Cas with the three different mounting flanges and put in a 10" IDmax subwoofer. That should sound awesome on 600w. For e92 the also have an enclosure, but you will need an adapter to make that sub fit.

Edit: You will also need an adapter ring for the e90 enclosure.

[Viktimize]

Originally Posted by kaigoss69

I have tried just about everything. Single 12" sealed, dual 12" sealed, single 10" in corner, SWS-8s under seats, single 12" infinite baffle, single 15" IB. Corner loaded will be the most efficient and best sounding in-trunk solution. If it were me, and I had $800 to spend,for the e90 I'd get one of those enclosures from Wicked Cas with the three different mounting flanges and put in a 10" IDmax subwoofer. That should sound awesome on 600w. For e92 the also have an enclosure, but you will need an adapter to make that sub fit.

Edit: You will also need an adapter ring for the e90 enclosure.

800$?? It's listed for under 400$ on their site.

[kaigoss69]

Originally Posted by Viktimize

800$?? It's listed for under 400$ on their site.

...and the subwoofer is free???

[nimo]

Thanks kaigoss! I'm wondering if we can do a group buy from wicked or from musicar. I've been looking at their magic box and musicar enclosure for several years.

[bmw325i]

Originally Posted by kaigoss69

I have tried just about everything. Single 12" sealed, dual 12" sealed, single 10" in corner, SWS-8s under seats, single 12" infinite baffle, single 15" IB. Corner loaded will be the most efficient and best sounding in-trunk solution. If it were me, and I had $800 to spend,for the e90 I'd get one of those enclosures from Wicked Cas with the three different mounting flanges and put in a 10" IDmax subwoofer. That should sound awesome on 600w. For e92 the also have an enclosure, but you will need an adapter to make that sub fit.

Edit: You will also need an adapter ring for the e90 enclosure.

A 12" idmax will fit too, you'll have a little more cone area.

[deadmn1337]

Originally Posted by nimo

Thanks kaigoss! I'm wondering if we can do a group buy from wicked or from musicar. I've been looking at their magic box and musicar enclosure for several years.

I have a corner load 12" musicar wired 4 ohms at 500w and it sounds great. There are no rattler that i can hear when bumping music. Definitely the way to go.

[kaigoss69]

Originally Posted by bmw325i

A 12" idmax will fit too, you'll have a little more cone area.

Nope, enclosure way too small for that sub!

[bmw325i]

Originally Posted by kaigoss69

Nope, enclosure way too small for that sub!

They don't list volume of the box,but it does seem kind of small. The 12" idmax only needs around a 1.5 cu ft. sealed box. Mounting depth wise it will fit.

[Viktimize]

Originally Posted by kaigoss69

...and the subwoofer is free???

No, but if you want to pay the ass rape price they are charging off their site I suppose that is an individual choice. Be able to get a much better price off Amazon or Ebay, or even craigslist. I have like 5 subwoofers laying around in my garage from previous vehicles.