Mbodall

Especially if you've replaced your factory Mark Levinson sub with a Polk, or Kicker, or what ever subwoofer, this thread is for you. From what I recall, the factory ML sub was designed for an open air application, however I'd be wiling to bet that doing what I did yesterday would improve the performance of even the original ML sub. Verified that this does improve the performance of even the factory ML sub courtesy of Atomsplitr:
To the best of my knowledge, most, or all of the aftermarket subs that are often put in the ML sub's place are either designed to be used in an enclosure, or can be used for either open air or enclosed. My car has probably the most commonly purchased aftermarket sub in it: a Polk DB840DVC which is designed to be used in an enclosure, either sealed or ported. I've been reasonably happy with it's performance for the 3+ years that I've owned my car, and this Polk sub was already installed when I purchased my car and had no modification done to the car to improve the sub's performance. I've read about a few other owners that have done what I'm going to detail in this thread, and was interested to see how much it improved the performance of the sub. I'm talking about covering all of the holes/openings in the metal of the rear deck where the subwoofer is mounted. Here are a few pictures where I circled some of the holes in the rear deck that I wanted to cover: (I didn't take pictures of all of the holes I covered, but once you have access to the area you can just look around the entire rear deck to find all of them. I think there are only 2-3 holes that I ended up covering that aren't visible in these pictures or circled) **Note that the subwoofer was not installed at the time of these pictures being taken.





So yesterday I went to a local stereo shop and bought some Dynamat adhesive soundproofing material. It's relatively inexpensive. The smallest package they sold was $25 and included (2) 12"x12" sheets of the stuff, but (1) 12"x12" sheet would have been more than enough, as I have about 1/4 of a sheet leftover in addition to the other sheet that I didn't touch at all. You can also buy this material online for less money, and there are many brands that do essentially the same thing.

To do the soundproofing, you first need to gain access to your rear deck where your subwoofer is mounted. I just posted an instructional thread with pictures here showing how you can gain access to this area within 5-10 minutes using only a 10mm socket, 12mm socket, and your hands.

Once you have the soundproofing material and and access to the rear deck, you need to know exactly what shape and how big of pieces you need to cut out of it to cover the holes. I used a reasonably accurate, quick, easy, but super low tech approach to this. I used a sheet of paper towel from a roll that I happened to have floating around in the back of my car. I basically eyed up the size of each hole I was going to cover and ripped off a section of paper towel slightly larger than the size of the hole to use as a template. Then I laid the ripped off section of paper towel over the hole to see where and how much I needed to trim off. I generally tried to make it so the section of paper towel completely covered the hole with at least 1/4" of material extended beyond the edge of the opening all the way around it, so the adhesive of the Dynamat has enough surface to stick to and make a good seal. Where clearance allowed, I made it so that 1/2" to 3/4" of material extended past the opening. Once I had every hole covered with paper towel, I laid the "templates" on the sheet of Dynamat and arranged them as efficiently as I could so that I ended up with as little waste as possbile. Here's a picture of that after I cut out the first section of Dynamat and covered a large hole with it:


I used a utility knife to score the sheets around my templates, then removed the pieces of paper towel and made the final cuts. Before applying the cut pieces of Dynamat to the holes, I took a damp paper towel and wiped the dirt and dust from around each one of the openings. Next I peeled the paper backing off of the cut pieces of Dynamat and stuck them on over the holes and pushed down all the way around each edge to ensure good adhesion. This is what it looked like after application:






The end result? Was it worth the hour of my time and $25? Unequivocally yes. The amount of bass coming out of that puny little 8" twerp of a sub astonishes me. I'm obviously not rattling windows around me, or even rattling anything on the exterior or interior of my car (good!), but it's a damn good amount of bass. And actually, I got out of the car in a parking lot with the stereo turned up to about 55 (I like to listen to music looooud lol) and could barely hear or feel the bass. To me though, I prefer that. I'm not playing my music for the enjoyment (or displeasure) of the other cars around me; I'm play my music for my, and my passengers' enjoyment. Also, you can be ticketed for playing music too loud in most places, so I'd rather my music be as loud as a concert only inside of my car, while still being quiet enough on the outside so I don't attract the unwanted attention of John Q Law.

I'm seriously pleased as punch with how my stereo sounds and don't know why I waited 3+ years to do this. If you wish your subwoofer had just a little more bass to it, I highly advise doing this. And those of you that might be worried that this may give your system too much bass, don't be. It's still only a little 8" sub and won't turn into a thumping 12" by doing this. Plus you always have the option of turning down the bass in your equalizer, and if you really must, it's not at all difficult to remove the soundproofing material, or you can even leave it in there and just punch holes through the material and render it nonfunctional.

2KHarrier

Nice write up Where were you 3 years ago when I had everything torn apart replacing the sub??

Oh well, this gives me reason to open it back up....

Atomsplitr

I did exactly this last year...works great with oem sub!

Mbodall

Good to know! I figured it would help with that. I'm going to edit the original post citing you as my source

Mbodall

At least now it'll be a lot quicker than the last time you dug into it!

rkw77080

Openings on automotive body panels (door panels, rear deck, etc.) are to effectively enlarge the overall volume of the cabin in an attempt to dampen/equalize any acoustic and pressure shocks you will experience within the car cabin. Next time you shut the door, keep an eye on your moon roof to see how it pops. Of course if you have a UL with soft-close doors, then you're OK. On the other hand if you're looking for the "kick", you're on the right track.

BigNel76

Mbodall

I definitely understand what you're saying and agree as far as the physics of that, but it would seem that the trunk itself is already sealed pretty darn well from the outside of the car, so mostly sealing off the cabin from the trunk doesn't seem to make much of a difference. And there are some small gaps for air to pass through to the trunk area, albeit very small.

CelsiorFin

Hi,

I also changed a few days ago oem subwoofer to kicker subwoofer (8ohm) and also did this soundproofing material fix at the same time. I also noticed same thing that the bass sound is too quiet.
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