I bought a '93 400E in April and started on plans to build a sub box for the trunk shortly thereafter. While the car came with an Alpine trunk mounted CD changer, and the stock system in a 400E is considerably better than my old 300E, I still wanted more bass. But having just talked the wife into the car, budget was a huge problem. (I ended up spending about $220, and about 6 hours of my own time.) I listen mostly to rock and blues music ranging from Genesis and Yes to Eric Clapton and Blues Traveler to Creed and POD.

I considered what to do for quite awhile, and pored over information on this web site for weeks before deciding I was going to build a box to go in the trunk, and port it into the cabin. In my previous 300E, I had two 8" free air subs mounted where the headrests are (They were removed.) and it sounded great. Free air subs are very hard to find, and I was loathe to take out the head rests again.

I could find nothing off the shelf that was even close to what I wanted. I decided to build my own box that would only take up 9 inches of depth in my trunk. It is 36" wide, and 16" tall. If I had to do it over, I would make it 15" or 15 1/2" tall as 16" leaves little wiggle room. I built a box with two chambers that work out to just about 1 cubic foot per side. I bought 2 Jensen 10" subs and a Jensen 300 Watt amp, both from Wal-Mart. I know these are cheap components, but after building several speaker systems, I have found that volume is the most important aspect of stereo system design. Some day I will upgrade the rest of the stock system and also go to better drivers and amps. I am pretty pleased with the Jensen stuff so far. It has proven pretty tough, and was REALLY cheap. The subs were only $35 each, and the amp $100 - brand new! I also bought a wiring kit which was invaluable.

I wanted to port out the top of the box into the first aid kit, so planned the design accordingly. I built the box of 1/2" medium density fiberboard. (MDF.) I know I am supposed to use 3/4", but I don't have a truck, and it was hard enough to get the 4' X 8' X 1/2" in my little station wagon! Actually, I was glad I used 1/2" as I think it was easier all around to work with, and still sounds good. I doubled the thickness on the baffle (Where the speakers mount.) and also between the two internal chambers, so I think that helps. I used 1 1/4" drywall screws and lots of wood glue to keep it all together. I painted it matte black, so I didn't carpet it. I bought a couple of stout speaker grills from Radio Shack to cover the drivers.

My original intent was to mount the speakers facing forward, into the gas tank, mostly to protect them. As it turned out, I had to face them backward because I got my measurements slightly wrong, and the speakers stuck out from the surface of the box so that it wouldn't sit flush against the back of the trunk. And I had already cut the holes for the ports in the rear deck! Thank goodness all I had to do was turn the box around - the holes lined up perfectly! (What's the old saying about measuring twice and cutting once?)

For ports I used 3" black poly pipe found at the hardware store in the sprinkler system section. It is extremely stiff, and easy to work with, and it really doesn't matter that it's ugly. I cut the holes in the rear deck with a small power jigsaw. The amp is mounted between the drivers. Figuring out the wiring was a pain as there is little documentation on it, so I just fished around and tried to figure it out. The on/off signal is from the power antennae, and high level input is from the rear speakers. Main power comes direct from the battery which is in the trunk. The stock system has at least two separate amps for the cabin speakers and small bass drivers in the doors.

So how does it sound? I would give it an overall grade of about a "B to B-". The warnings on this site regarding the sound muffling properties of the E class trunk are well founded. Without the ports, I doubt I would hear much of anything - they are built SO well! The sub adds considerably to deep bass, and can shake the whole car, depending on what's being played. Because I am only getting the backside, or ported energy from the subs, I am definiitely losing a lot of sound, especially mid bass. But the alternative would be to mount speakers in the rear deck, which would be a whole lot more cutting, and would require hard to find drivers. (Or find a stand alone unit that would hide in the cabin somewhere - a tough problem.) If I had stronger subs, and a BUNCH more power, I am sure I could improve the sound to an "A". I would probably also need to upgrade my power source as well.

I hope to have pics added soon. Please email if you have any questions!

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Mike in Denver
'93 400E Now DEAD - Rear ended and totalled.
Replaced by '02 C32 AMG - FAST!