stu_pidaso

My W222 has the Burmester sound system and it sounds great but for the lowest bass notes. The stock 'sub' woofers are located beneath the front passenger and drivers feet. They roll off sharply at 47hz and this is a function of a subsonic filter hard-coded in the factory amplifier. This is not a huge problem because of cabin gain, but 40hz is about 10db down and so I want to enhance frequencies between 20hz and 40hz. There are quite a few difficulties reproducing such low frequencies but the finer points are beyond the scope of this posting. You will want to use a driver (woofer) with a FS (free air resonance) at least as low in Hz as you wish to reproduce, the larger the cone area and the higher the XMAX the better. The larger this driver is the bigger it's enclosure will need to be. In order to match the same SPL as the stock Burmeister system but reproducing only a single octave from 20hz to 40hz I settled on a woofer by Stereo Integrity. Here are it's specifications:

HT-18v3
T/S Parameters (coils wired in series):
Re: 4.2 Ohms
Fs: 23.1 Hz
Qes: 0.69
Qms: 4.11
Qts: 0.59
Le: 4.7 mH
Sd: 185 in^2
Vas: 220 Liters
BL: 19.7
Mms: 434.1 g
Cms: 109 uM/N
SPL: 91.67 dB (2.83V/1M)
Xmax: 25 mm one-way via 70% BL
RMS Power Handling: 750 watts RMS
Cutout: 16.56″
Outside Diameter: 18.0″ (without gasket)
Mounting depth: 9.17″
Basket OD flange thickness: 0.35″
Gross Weight: 36.3 lbs
Net Weight: 33 lbs
Sealed enclosure recommendation of 4 ft^3.
Ported enclosure recommendation of 8 ft^3 tuned to 22 Hz.
ULF Ported enclosure recommendation of 18 ft^3 tuned to 18 Hz.
SULF (Super LFE) Ported enclosure volume of 22 ft^3 tuned to 16 Hz.

As you can see, the suggested Super Low Frequency Enclosure volume is 22 cubic foot vented enclosure. This is a big box. I want to use the trunk of my car for things like groceries, ski boot bag, or golf clubs. As a matter of fact, I don't want to lose any trunk space at all.

As it happens, the W222 (and many other S-Class vehicles) have a carpet/plastic divider between the trunk and the electronics mounted on the back seat. Up to the divider, the trunk has 26 cubic feet for storage, but a total volume more like 32 cubic feet counting the nooks and crannies (I just made up that second number - it's a total guess.) Rather than a box I constructed a pseudo "infinite baffle" enclosure. I have experience with such woofer loading when building home theaters, for instance. Certain woofers lend themselves well to this sort of alignment - where the woofer is basically mounted into a wall - which is separating the front wave from the rear wave of the driver.


Area between back seat and trunk divider.


I removed the divider separating the trunk from the back seat, and noticed a few interesting things. There are factory nutserts in multiple places along the trunk floor that are unused. Additionally, the power distribution box is located behind the passenger side rearmost seat near the back deck. It has unused lugs on it which I determined are fused at 150 amps and are constantly powered. The space between the shock tower / wheel wells and rear deck and trunk bottom is basically a perfect rectangle - if a baffle board is cut with 7 degrees of tilt on top and bottom cuts with the bottom of the board closer to the back seat and the top of the board closer to the rear of the car a board can fit snugly.


Actual space normally hidden by rear seat / trunk divider - note unused threaded nutserts



Mockup for power cable length from OEM power distribution box to amplifier location.

Trunk pre install.


I built the baffle board from 1-1/8" thick flooring material, normally used to lay across joists, then tile or carpet or hardwood would be installed on top of it in a home. I chose it because it was easier to get than baltic birch, and far cheaper since I would have to use two pieces of birch laminated together to obtain the desired thickness. I cut a small tail piece which lays between the bottom of the back seat and the baffle board, flush with the trunk bottom. I glued and screwed and clamped these together for 48 hrs. Then I cut the hole for the driver. I used Bondo to fill the various imperfections in the wood, and sanded it down smooth, then painted the entire baffle board black with primer. I drilled holes for T-nuts which I installed and stapled in place with a brad nailer. Then I covered the board on both sides with contact adhesive, and coated some black vehicle carpet as well, stuck the two together and cut out the hole in the carpet for the woofer.


Baffle board prior to painting.

7 degree cant of baffle board at left compared to trunk bottom plate with clamps on bottom.


The amplifier I'm using is an Audio Control LC1-800 and I'm using this amplifier for a couple of reasons. It's a mono amplifier and being class-D is quite efficient which we want so as not to work the vehicle charging system greatly. It has a high level input built in, basically an LC2. Most important, the amplifier has a 'bass restoration' circuit that allows the restoration of the lowest and almost non-existent bass notes to be louder, with higher gain level than being presented to the amplifier. I need this because my signal is being derived from the factory amplifier output, tapping into the blue (-) & blue with white wire (+) which are driving the aforementioned OEM subs mounted beneath the front floor of the car. I used a couple of yellow tap connectors to tap into this wire (it's not critical to tap into both the brown and blue (left and right) sub output wires since they're summed mono already. I used a 18" long orange 1-0 awg welding cable for my hot lead and a 22" long cable for my ground lead to the amplifier. The lugs are not large enough to accommodate this size wire, so I used some lug adapters that are meant for big variable frequency drive (VFD's) adapters used in commercial motor speed controllers. (photo) My lugs are compressed with a Burndy PAT4 hand held hydraulic crimper, then heat shrink with the glue in it is melted over the crimp. I had to grind a bit of the lug away on the positive lug in order to get it to fit into the OEM power distribution box.


1-0 awg welding cables with lug adapters.

Lug adapters


My car does not have the refrigerator in the trunk, but has a little box behind the middle armrest that folds down in the back seat. That box can easily pop out by loosening two #10 plastic bolts in the rear area. Now you have a hole from the trunk to the vehicle interior. My intent is to mount the woofer so the magnet is visible through the pass-through with the cone only visible when the trunk is opened.


Center pass through box to remove (easy peasy)


I also purchased an additional LED driver for my W222 from Alibaba, and intended to use it to illuminate the driver from inside so one could look back and see the same color illumination as the vehicle interior has, but the items from Alibaba showed up non-functional TWO TIMES in a row and I gave up on that and since I keep my interior red all the time, I am only going to run a single red led strip in there and call it good.

Now, I simply put the baffle with carpet, sans driver - into the space and with a bit of effort (both feet pushing against it with my body completely in the trunk) I was able to get the baffle into place. I then connected the amplifier lugs to the amplifier, used the metric T10 bolts I had bought from Tacoma Screw to affix the bottom of the baffle board to the factory nutserts in the trunk floor. Then I mounted the woofer.


View of the amplifier and woofer magnet from the cabin looking through the pass-through.


woofer as seen from the cabin side

another view through the pass through from the cabin



I set the low pass filter on the amplifier to 45hz and turned the bass restoration up all the way.

The results are fantastic. My wife borrowed my car and went to the store, and said the woofer I had installed doesn't even work because she can't hear a difference. Great! She listens to the radio anyway, there's no low frequency information in the top forty radio crap anyhow. I assure you, the low end now hits extremely hard when listening to certain types of low frequency music. From organ music, dubstep, electronica, to rap the system hits hard like you think it should. It's also great for movies, explosions and gunshots and helicopters and other LFE stuff in the movies my kids watch when we're driving up to the ski area are quite a bit more immersive now.


Baffle installed with woofer mounted.


Essentially I have no vibration anywhere in the vehicle and when the doors and trunk are closed with the system turned all the way up outside you really can't hear it. Well, you can feel it certainly, but it's not obnoxious to the neighbors as long as I have the windows up and doors and trunk closed they can't hear me driving up even listening to 'Charlie' by Shootergang Kony. Inside the car however, these low notes cause ones visual perception to be blurred momentarily due to the pressurization of the cabin, but this is only when the gain is pushed up to uncomfortable levels.



I hope you enjoy the photos, if you have any other questions I am happy to help.

drose224

Kudos to you for your tenacity, skill and knowledge of the audio system. Nice job.

superpop

Looks good, I did a pretty extensive upgrade to the audio system in my S550 but I recently sold the car. I like the idea of an infinite baffle. I had a sealed enclosure that sat in that spot with a JL Audio WA7-10 Sub that hit like a jackhammer. Drove it with a JL VXi 1-1000 sub amp. For the mids and highs I ran a JL VXi 800-8. I bypassed the factory amp via a NAV-TV Fiber Optic converter that grabs the raw fiber optic signal off of the HU and converts it to either RCA or Toslink signal. The factory speakers are actually great at the higher frequencies but the JL amps really woke them up.

SteveE400

Free-air subs never seem to get the love they deserve. Many years ago I did a free-air sub with a 500-watt class D amp in the trunk of a Lexus LS430. Night and day difference compared to stock system, while all the added electronics were invisible. Win/win.

I haven't messed with my E-class, though. I'm a lot older now, and don't feel like turning my body into a pretzel to get in there to work. Tempting, though. . .

stu_pidaso

Actually it was your post with the JL amplifier and LC2 that got me motivated to do my install. I believe you're located in a suburb of Bellevue correct? Funny you've sold your S550. Did you restore the sound system to its original state? Regarding selling -- the dealership called me on Friday and offered me $20k more for my car than I paid for it which I am seriously thinking of doing. How often does something like that happen? I'm going to remove the baffle and put the car back to how it was before I do it. So, all this work for naught but hey, it was fun and I enjoyed it.

Maybe someone with a W222 or W223 will want to purchase this from me for a great price.

superpop

Ya, I am over in Newcastle just south of Bellevue. Traded in my S550 4Matic for a 2019 S63 that goes like a raped ape. The S63 came with the Burmester 3D set up so I am selling all my gear as I removed it all and restored back to factory. Amazing what cars are worth right now, I purchased mine 4 years ago with 15K miles for around 59K and they gave me close to 50K on the trade with 55K on the odometer.

imprezkid

@stu_pidaso Where did you tap into the speaker wiring? I was going to ask about the amp options but after reading again and see others had to add an LC2 for the amplified inputs this seems to be a smart way to go and keep things simple. I'm not a huge audio guy but this doesn't seem to bad for around $1k and a little time.

Thanks in advance