Why are we not using infinite baffle woofers

[DocMike]

Having used the JL stealth subs in my e46, I wonder why we have not been using a infinite baffle Sub in the back hatch of our X5. It is sealed off from the cabin, you have more airspace, and the install is a lot cheaper and much easier, and most like better sounding. Seems like you have to cut that lid anyway to add a grill in a lot of the installations, so why not pop a infinite baffle subwoofer in there and a grill>?
Infinite Baffle
Infinite baffles (IB), often termed "Free Air", are possibly the simplest enclosures to build, and a great way to conserve space. This design is defined as an enclosure that contains a greater volume of air than the Vas of the speaker. Applying an infinite baffle system in an automobile is relatively easy. The concept of an infinite baffle is to isolate the sound wave produced by the front of a speaker from the back wave. This normally involves mounting the speaker(s) on a board that seals off just behind the rear seat while using the trunk of the vehicle as the enclosure. When all is said and done, an IB enclosure is truly quite large.

Trade-offs come in many forms when working with IB enclosures. Sure, using IB enclosures conserves a lot of space, especially in the trunks of smaller cars. However, there are some losses to be noted. The most prominent is efficiency. Without a solid structure built around the woofer, it is difficult to reinforce the sound. Trunk interiors are filled with flimsy panels, thin sheet metal, and usually a measly spare tire -- none too pleasing for sound reproduction. This same issue holds value with the speaker's power handling. As much as 50% of the nominal power handling of a woofer can be lost when placed in an infinite baffle. Another anomaly that plagues IB enclosures is the tendency to lose control of cone movement when played below the Fs (resonance frequency of the driver), much like ported systems when played below the tuning frequency. For this reason, it may be desirable to utilize a subsonic filter below the Fs of the speaker.

When purchasing IB speakers, keep in mind the following parameters to assure that the speaker is right for the application. The first is the Qts (the total resistance of the driver at its resonance). Speakers with a Qts greater than 0.6 typically work well in an IB environment. The second is the Vas (the volume of air having the same compliance as the driver's suspension). The Vas should be smaller than the total volume of the environment the speaker(s) are being placed in.

Good: minimal space consumption; generally easy to build.Bad: poor efficiency; sometimes difficult to isolate front and back wave; limited cone control below speakers fs.




A True Infinite Baffle Subwoofer

[DocMike]

am I missing something here, seems like a very logical install. Why are we trying to stuff small boxes and find tiny thin drivers when we can do IB set ups??

Here are some examples of IB installs

http://www.sounds-good-stereo.com/ap...?categoryid=13

[DocMike]

woofers
Elemental Designs

[DocMike]

Best IB woofers, 2 of these on each side...
DLS Performance OA8 8" open air subwoofer

[DocMike]

Best IB woofers, 2 of these on each side...
DLS Performance OA8 8" open air subwoofer

[m5james]

I've got a stock enclosure coming in the mail that I got for free, then I'll be cutting the face off to fiberglass a piece of MDF to mount my Kicker L5 8". I'm not against infinite baffle at all, but then again I haven't heard one in person for YEARS.

What are you using for your sub setup?

[DocMike]

M5james, I used to live in Kirkland, and Seattle, lol. I learned how to fiberglass at the same time Steve Brown (from Alpine) did as one of my best friends lived below him and his wife Amy and taught Steve how to lay fiberglass down. That was when he was working on his MB Quart Celica and later the Acura before he went big time in California.

Anyway, I was just looking at the space and thinking where is this thinking coming from? Because the OEM used a small box, and logical progression leads to figuring out how to use a small enclosure. So much space in there, and woofer technology is a lot better now, than it was in the 90's. That being said, I wonder how 2 8's would sound IB install in the back hatch compartments. I thin I saw a picture of an X5 with and Infinite Baffle sub, but I can not find it.

I had a stand alone kicker box with a 10' and a BSW. I was going to do the same thing you are doing, but was concerned about the limited airspace in that box, and the plastic to resin interface that takes place. I have done this for trim pieces and such, but never anything that needed to be sealed and withstand pressure .

[m5james]

Abridged version - born and raised in Edmonds, then Great Lakes, Memphis and Va Beach for the military. Moved back to Edmonds, Kirkland, out to Alexandria and DC, then back to Washington in Puyallup, Edmonds, and back to Kirkland again. Now in Boise, awesome summer weather, but ready to go somewhere else...to small here!

I've never learned to fiberglass, but I've watched countless TV shows and friends do it, including my friends son in Marysville who made my current 7 and X boxes.

I'd be all for two 8's, having one on each side mounted directly to the panel itself since I don't have factory nav, so I've got the room. Am I thinking of free air subs? I think I just confused myself.

What do you mean by stand alone? Is it a free air setup? What is the BSW, you've got two subs going? I agree that airspace is small in that plastic enclosure, but the Kicker L5 8" I've got is designed for small enclosures. I've read reviews and apparently Kicker makes their subs to work in the sweet spot of most rap, dance and other types of heavy bass music...which is what I mostly listen to anyways. I get my occasional kicks from listening to old Van Halen, Depeche Mode, etc from when I was in middle school, and I've read that most rock music like this won't sound nearly as good. My amp has a bass knob, so I can tweak as needed just like I do now...most rock I've gotta crank the knob all the way up w/ a couple bass adjustments on the stereo as well, while the rap/dance stuff is exactly opposite settings. I'm iffy about the whole plastic enclosure thing, so once I learn to MDF the face on, I also plan on using a heavy grit sanding paper on the entire enclosure and fiberglassing the exterior of it to add some type of reinforcement. Once it's all cured, I'm going to spray rubberized coating over the entire enclosure like I did in the open areas of the X5 itself. I don't have pics of the enclosure on this pic, but here is the link to the thread which I'm sure you've seen before http://images.google.com/imgres?imgu...FdK0tgeopq2QDA, particularly post 85.

While searching for the above thread, I found this pic....insteresting idea. Google Image Result for http://memimage.cardomain.net/member_images/3/web/543000-543999/543889_54_full.jpg

[Brit6]

A lot of people like the clean look with the bsw subwoofer installed into the compartment without altering the hatch cover in any way.

Originally Posted by DocMike

am I missing something here, seems like a very logical install. Why are we trying to stuff small boxes and find tiny thin drivers when we can do IB set ups??

Here are some examples of IB installs

Sounds Good - Projects

[admranger]

I have an IB install on my wife's 2002 M3 (documented in bimmerforums), though not a true subwoofer setup, it is more of a mid-bass using Hybrid Audio Technology L8's in the rear deck. Bigtime improvement over the HK system "subs" (ha!) and a side benefit is more headroom in the trunk!

I'm looking at an IB in the X5 too, but only in concert with a full speaker/amplification upgrade (want to keep stock nav headunit). Still in research phase at this point.