I just installed my 5.25" component set in my E36, and the bass-midbass region is quite weak. Basically I've narrowed it down to possibly the weak foam padding that was behind the stock speakers is either leaking or absorbing some of my bass-midbass (it's not playing much, if anything, below 80Hz)

What's behind the foam? Is it just bare metal? How well is it sealed? Has anyone tried taking the foam out?

u dont want to take the foam out, and it is just bare metal behind the the foam. u can put some polyfill (or pillow stuffing) and that should help dampen things out a bit. other than that midbass just sucks with 5.25" mids and a small sealed enclosure.

Can you elaborate? Wouldn't stuffing make the enclosure even smaller?

The reason I'm concerned is that the stock Nokia speakers in the back (the 4T ones) seem to hit lower on HU power than my components off amp power! Over at caraudioforum.com, others are reporting their 5.25"s going down to as low as 50Hz, from a small kickpod. (Probably better sealed, but in terms of enclosure size, don't think it's much bigger than our kickpanels, if at all)

u dont want to take the foam out, and it is just bare metal behind the the foam. u can put some polyfill (or pillow stuffing) and that should help dampen things out a bit. other than that midbass just sucks with 5.25" mids and a small sealed enclosure.

Stuffing makes it appear larger... Try using deadening on the door, it will stabalize the doors so more power is sent through the mid.

Most mids are not made for tones below 80hz. Most people using sq systems highpass at 80-120hz, never heard a good sounding system crossed over lower. Maybe the stock speakers hit louder... Lots of speakers usually use a sort of IB setup. The larger the enclosure, the easier it is to power it. Some speakers just dont have the Fs to hit that low too. They usually have a F3 at about 80 hz.

Clayman,

I have graduated from factory speakers to 5.25" a/d/s 325is separates in the factory kicks to a fully custom front stage with 7" Dynaudio drivers in the kickpanels.

Behind the kickpanels, it is basically metal and "space." Even though you will not get tremendous mid-bass response from 5.25" drivers, it is worthwhile to mat or sound deaden both the front and back of the metal the driver mounts to. I use Brown Bread, but you can use anything you desire (RAAMmat, Cascade, Dynamat, etc...).

If possible, mount your speaker to a baffle, or frame, before you attach it to the metal. This baffle will ensure that the speaker is mounted solidly. Baffles are usually constructed from MDF, which you can buy at your local hardware store.

I would agree with others that some sort of absorption material should be used in addition to the mat to achieve a more linear response from your drivers. Be weary that some absorption material retains moisture - this is bad since moisture can obviously cause rust some time down the line. My advice is to try a material called Ensolite. Ensolite is a material developed by NASA to absorb shock, is impervious to moisture, and is an excellent sound absorber. It is cheap to buy - I would recommend it in 1/8" width size. I learned this trick from Rick McCallum, a fanatic in car audio.
http://www.raamaudio.com/fanaticmechanic.htm

Ensolite is available at his website as well or your can find it searching the web:
http://www.raamaudio.com/products.htm

Just to let you know, in that article, they spelled Ensolite incorrectly as Insolite.

Another suggestion is to use Cascade's Deflex pad to the rear of the speaker. The Deflex pad is made out of a liquidy rubber that is supposed to absorb rear sound waves from the driver.

http://www.cascadeaudio.com/prod/deflex.html

I hope this information helps.

P.S. I am NOT affiliated with any of the above companies. I'm just trying to pass on some knowledge.

WK446 covered it pretty well, but I would also like to push second skin audio, they use a lot of the same materials and have different things for different type setups

Wow, thanks WK446 for all that information.

Are you suggesting that I rip out the foam padding? Is there a lot of extra space behind the padding, that's potentially hard to reach?

Also, about mounting. I suspect that their may be leaks on the edge, because the plastic grommets that the screws go into are protruding. Thus, regardless of how tight I screwed my woofer in, or even if I made an MDF baffle for it, wouldn't there still be a leak there?

Clayman:
No problem.

I wouldn't rip out all the foam padding, but it is better to start with a "clean slate." Anyways, you will be replacing the foam with something better (hopefully).

Once you construct a baffle, you can silicon the baffle to the metal of the kickpanel area to prevent any leaks. Do not silicon the speaker to the baffle - only the baffle to the metal. I would do this as a final step once everything has been completed.

Take your time as you will be rewarded for your patience.

Finally did the test -it's no wonder music sounded so empty. After listening to a variety of test tones and sine curves, the drop off around 160Hz downwards was pretty obvious, and it was all downhill from there. Needless to say I"m extremely disappointed - the speakers aren't being underpowered (overpowered probably actually) - the kickpanel enclosures can't be THAT small to be killing so much midbass right? I'm hoping that it's just a leak around the woofers...

Finally did the test -it's no wonder music sounded so empty. After listening to a variety of test tones and sine curves, the drop off around 160Hz downwards was pretty obvious, and it was all downhill from there. Needless to say I"m extremely disappointed - the speakers aren't being underpowered (overpowered probably actually) - the kickpanel enclosures can't be THAT small to be killing so much midbass right? I'm hoping that it's just a leak around the woofers...
if they sound like crap around 160hz u have a serious install problem or the speakers may be messed up...did u screw in all 4 sides when screwing the speaker into the kick panel?

if they sound like crap around 160hz u have a serious install problem or the speakers may be messed up...did u screw in all 4 sides when screwing the speaker into the kick panel?

Yup. The speaker's not your run-of-the-mill component speaker though, as you can see here: http://www.drdetailshop.com/v550.2.htm

The whole basket is built into the woofer.. A nice and thick aluminum frame that gets in the way of everything. (i.e. the kickpanel covers) It protruded so much that I didn't think MDF baffle would fit. Also, the 6 holes don't fit the BMW's four.. So I decided to drill the BMW locations in. It's a pretty tight fit, but the foam padding gives quite a bit, so I don't really know how far to screw it in (it just keeps going farther and farther, the foam more and more compressed...)

hmmmm.....that could be a problem, one thing u could do is make some mounting rings out of some wood. mount em on there, then screw em into the kick panel, then use some silicone or any kind of sealant to seal up any air leaks...

This weekend, I'm gonna take one kickpanel off and see what's going on. Probably gonna try some weatherstripping around the ring of the speaker, and maybe some polyfill inside.

I was originally gonna use the MDF baffle/spacer as you suggested, but due to the protruding basket, this would require even more dremeling of the kickpanel cover, assuming it fits at all. Hopefully the weatherstrippingw ill be enough for now.

Oh another thing... There is an indent in the padding to let the two speaker wires out of the "enclosure"... Doesn't that leak air??? How do you guys deal with that?