Re: Anyone have dual subs installed in their E32s? (archive)

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Everything depends on the type of music you listen to, how loud you want it to play, etc. If you can provide more specifics, I may be able to help out more.

I bought a 1991 7501L about a month ago. The previous owner had sealed the ski hole and installed two 10" Infinity subs in free-air mode, using the trunk as an enclosure. The subs are mounted in a plywood baffle board that is attached to the underside of the package shelf.
There are two 8" grilles for the sound to enter the passenger compartment. It sounds quite good - good enough that I won't change it until Summer! I used to do custom stereo installs for a living so I will probably improve on it to get my ski hole back.

You have a lot of options. There is nothing magic about any enclosure type. They can all sound excellent. If you want to port through a small hole, bandpass is a possibility. The opening of the port(s) must be unobstructed, other than a metal or cloth grille. Single bandpasses are better for this: one port = 1 hole. 4th order bandpass enclosures tend to be large if you want to get any real deep bass out of them. They are also very efficient. I had a Super Duty Ford van with two 12" subs (Orion XTR) in 5-cubic foot double bandpass boxes that, driven with 400 WRMS each, produced 138 decibels and still placed in sound-quality competition. One would still be overkill for most applications. The boxes took me weeks to design and days to build. They weighed over 120 pounds each. Single bandpasses are much easier, as are sealed or ported. Direct cone radiation into the passenger compartment is the easiest way to good bass. Sealed boxes or a free-air application takes up the least space.

Anyway, it sounds like you are starting from scratch so here is some general advice:

1. Get a head unit with at least a 3 volt preamp output if you are buying a new one.

2. Install superb quality 6.5" ot 5.25" speakers up front. Stick with 2-way. Use factory for rear fill.

4. The bass system consists of the sub(s) and their amplification. These must be matched. To get a lot of bass, you need to move air. This takes cone area and watts. To get tons of high-quality bass takes lots of both. Keep your low-pass frequency below 100 Hertz for best overall SQ. If all you want to do is boom, other rules apply.

5. Decide if you want to install grilles in your package shelf or otherwise modify your interior. A lot depends on this.

I'm talking custom built speaker cabinets whether self built or professional installs. I've resisted the urge up until this point, but I'm thinking about adding a system to my 740i.

I'm thinking about using a 4th order bandpass enclosure and porting through the ski hole, and I'm wondering if I'll get the desired bass effect I'm looking for with that setup.

I've considered a sealed enclosure, but I don't like the standing wave problems encoutered with them for a trunk mounted box.

I'm looking for success stories and differing opinions, so what's in *your* trunk?

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