Satan1974

Sorry for yet another subwoofer post - I am yet another one who did not order an upgraded stereo with my car and thought it would be easier and cheaper to upgrade afterwards!

Anyway - I want to put a subwoofer in the boot (that's English for trunk !) but understand that due to all the soundproofing, it's not as easy as it should be. I was thinking - rather than put a full sub enclosure in the boot, would it be an option to fit a sub speaker directly to the underneath of the parcel shelf, and maybe cut out some etxra holes and pull out some of the soundproofing?

I don't want to lose too much boot space so really don't want to have to stick a HUGE speaker and enclosure in there, and also I want the bass to sound louder inside the car than it does outside - after all I want a sub so my music sounds good to me, not people that I am driving past

So what do people think - is a sub mounted directly to the metal underneath the parcel shelf and facing upwards (just like the other two speakers already there) a good idea and viable option? if not, why not?

Thanks

Heiss5

It's a viable option yes. A good idea, not so much. I wanted to cut/modify that area to mount my amps there so that they would be out of the way and I could get my subs in as far as possible, but then I was told that that section of the car actually supplies structural support and stability, almost like a built in anti-roll bar. No trusting stereo shop would cut into that area unless your car was going to be for show. I suppose you could build a reinforcement after installing everything, but that is kind of sketchy. You could mount it to the metal without cutting it, but I don't know how that would turn out, and you can always remove soundproofing. I don't think you're going to have a problem with other people hearing your bass unless you go with a competition setup. Overall, the subwoofer in the armrest like vishwen was talking about actually looks like it would be a good alternative for you to go with, I don't know if you're interested in that though.

subterFUSE

There are two ways to mount a subwoofer in such a configuration:


1. Infinite Baffle

2. Aperiodic Membrane




An infinite baffle is basically a subwoofer which has been installed in the rear shelf, without an enclosure. This setup is sometiimes called a free-air enclosure, because of the lack of a true box enclosure as found in sealed, ported or bandpass enclosures. The trunk space itself functions as the enclosure. A subwoofer must be specially designed in order to function properly in an infinite baffle setup.



An aperiodic membrane is another way to go. An aperiodic membrane is a air-permeable sheet which is used to form one side of a sealed-type enclosure. This allows the subwoofer to be installed using the smallest box size possible, and results in the best sound quality of all subwoofer designs. The result is super-tight, accurate bass..... but not as much loudness or boominess. These setups are very difficult to design and tune, so they are only common in Sound Quality competition installs. Not all subwoofers are well-suited for aperiodic enclosures. Only subs with a Qts rating of .46 or lower make good candidates.

There are several ways to build an aperiodic enclosure. This article is excellent, and explains aperiodic enclosures far better than I ever could:

Aperiodic Membrane



If I was going to build a stereo for my E60, I would use an aperiodic membrane enclosure for both the sound quality and to save trunk space. I think the best design to use would be to build a box which fills the opening where the fold-down seats are... and fires the subwoofer into the car through the armrest. The aperiodic membrane would be on the back side of the subwoofer box, venting into the trunk. Since the box size should be as small as possible, I would have the box shaped around the subwoofer basket so that only the center part of my box extends into the trunk space. This would leave more room on either side for luggage/cargo.

Another option would be to remove the spare tire, and build an enclosure into the well. In this setup, the aperiodic membrane could go over the woofer cone.... or could vent outside the car if I cut a hole in the tire well.

bobduch

I am going to try to do subs (Velodyne car subs) in the rear deck (2006 530i). I have fold down seats and the power sunshade. I am thinking of a 1/2" Baltic Birch plywood reinforcement to the rear deck and to mount the subs onto.
That deck does not provide any "vehicle" support with the fold down seat option. The plywood reinforcement should make up and then some for the woofer holes.
Just curious if anyone has tried this yet and if so do you have any tips?
Thanks!
Bob

Merzbow

I've drilled through the rear deck to bolt down a sub box sitting in the trunk. But although the metal is strong, it bends quite easily, so I wouldn't hang any subs off it without a good deal of wood reinforcement. A bigger issue is that true to form BMW has scattered various electronic doohickeys across the top of the rear deck. You'll have to do some rearranging to make room. In addition, you may have to remove the rear window in order to get the subs in. And, of course, it's no picnic cutting holes in metal like that; I certainly couldn't do it. I imagine you'd need to find somebody experienced with a welding torch.

In other words, I wouldn't suggest even thinking about this project unless you are a fabrication/shop expert.

subterFUSE

The liklihood of finding anyone qualified enough to perform such surgery on a $70,000 BMW is slim.... Only the very best of the best audio shops might have someone. And those are not everywhere.

I would suggest finding a different way to install the sub. I think the boxes which fire through the center armrest look like easy installs, and should be effective.

bobduch

I specifically got the fold down seat to be able to occasionally drive the car (and not the van) to Vail on weekends with my road bike (bicycle) which just fits inside with the fold down seat. Thus the armrest location is out. I've done several shelf mounts before. This one would be the most difficult because of the sunshade but I think I've got it figured out.
I've got access to the home wood shop of a very experienced wood worker.