Hey Guys,

I know it’s been a while since I contributed last, been occupied with a few other projects taking my time so I haven’t had a chance catch up with the tank. The good news is I have quit a few little modifications coming up for the ML63, so stay tuned over the coming few weeks…

Background:
One of the modifications I have wanted to do for some time is the OEM Subwoofer Bass Port modification. The stock Harmon Kardon system is actually pretty good as far as most OEM systems go. It’s definitely a setup up from the old Bose systems back in the day. One thing that bothered me is that the OEM stock subwoofer has no actual port to the cabin. On previous cars anytime the stock setup did not have a subwoofer bass port into the cabin, I always added one for minimal costs and the improvement was quite profound for such a small investment in time & money. I decided to do a small DIY write-up for those wanting to take on the small weekend project at their leisure. This is specifically for the dove grey interior. For those with black interior its even easier as it requires no paint work whatsoever, you just drill and install the grille and done

Time Require: 1.5-2.0 hours at a very leisurely pace

Difficulty: 3/10 (at most)

Parts, Tools & Supplies:
5” Hole saw = $38 (available at Lowes or Home Depot)
3/8ths Drive Arbor (anchor for the hole saw to adapt to any standard drill, Home Depot) = $15
6.5” Metal Black speaker grill (with screw hardware) = Only $12 (off Amazon Prime, Free shipping)
Rustoleum light grey primer (also Home Depot) = $6-8
Shop Vacuum with narrow attachment to clean up plastic shavings
** Always please use gloves and safety goggles as material will be flying everywhere, safety first! **

Prep work & Install:

The stock subwoofer is a 6” subwoofer. Originally I bought a 6” hole saw, but I quickly realized that this left almost no margin for error as the opening in the speaker grille was also 6” and the screws would be drilling so close to the edge that I was worried the lack of enough plastic material around the screen would case the holes to give and rip right now. After this realization, the 6” was quickly returned to Home and swapped out for the 5”. In retrospect, 5” is more than enough; it did not in any way effect the overall significant improvement.

For the black interior cars, this mod is a piece of cake, ignore all the paint related instructions and just drill the large 5” hole in roughly the center portion of the opening. The proper location of the hole should be in the middle of the circular opening in the insulation material on the back side. You must drill the hole from the front carpeted side, but position it roughly so that it comes out centered on the back side in the opening where there is no insulation material.

For those with grey (or beige interior), prep by getting some old paper grocery bags and place them on the ground and put both the speaker grille front over, and the grille mounting frame on separate backs on the grass somewhere. Do two light coats of the grey Rustoleum (or beige depending) primer with roughly a 20 min break in between the two coats to allow time to drive. I recommend doing it in direct sunlight to speed up the drying process.

While those are drying, begin to prep for the drilling of the hole. Lock the 5” hole saw into the arbor by pulling back on the arbor chuck, screwing on the hole saw onto the arbor’s mounting threads, then push back up on the arbor chuck to lock it into place on the locking holes on the hole saw. Lock the arbor bit into any standard electrical power drill of your choice.
Originally I tried to drill the hole from the backside but quickly realized why this won’t work. The backside has thick plastic supporting ridges which catch violently on the hole sale and make it impossible to drill from the back side. For this reason you need to drill from the front side to make it a clean hole. Remember once you start trying to drill the pilot hole, the second the hole saw makes contact with the carpeted front side the panel will twist violently so please make sure to do this on a shop bench and hold the panel firmly in place. Once you drill the hole (which only takes about 2-3 min, little plastic pieces will fly everywhere and get caught into the carpeting itself. The next 20-30 min will be spent cleaning up all the plastic shavings that got everywhere (using the shop vac). It will take a while to do this but it’s important that you get rid of all of them.
Once drilled (photo below), you can begin mounting the grill mounting frame with the 4 provided screws (some on amazon come with the screws, others do not, make sure you buy the one that comes with the screws). The mounting surface is not entirely flat, but if you screw it in properly, the frame will arc slightly, but the top grill will still sit flush as the screws will “pull” the back of the panel closer making it more flat thus making it almost a flush fit.

Once the frame is drilled, simply slight on the top speaker grille and … voila! That’s it.

Results / Improvement:
- At least 15-20% improvement in Bass volume & sound quality
- No longer muffled/muddy sounding bass
- Completely eliminated all the rattles associated with base coming from the trunk area
- Sounds almost like an aftermarket system but without any of the headache/hassle
- Cost almost nothing to do and seamless integration
- A “Must-Do” for your ML

Conclusion:
I could not be happier with the results. It is such a simply mod that yields such great results. My only regret is not doing this years ago. It’s the best way to improve your stock sound system for under $100 and I highly recommend doing it as a fun little weekend project. If you have a black interior, you would possibly even get away with just drilling the hole and not even getting the speaker grill, but I wanted to try and make it look as OEM and “finished” as possible. If you want to save even more money and time on a black interior car, you can just drille the hole and be done too, totally up to you.

Hope that helps,
ML63 AMG

 

Great work! I'm definitely interested in doing this. But just a question, would you yield the same gain by just taking off that cover?

 

Never mind. I just checked the back and there is a bass port. It's a square Harmon Kardon speaker cover similar to yours but this is stock. They probably added this with the refreshed models as my is 09.