Thought I'd share my experience installing new speakers in my 1988 300E. After reading through all the posts I could find here, there seemed to be some debate as to whether or not a 5.25" speaker will fit in the stock dash locations in the W124. Since I had found a great deal on a set of MB Quart Referenz QM130.03kx 5.25" coaxials, I thought I'd attempt to install them. A total stealth install was very important to me. I did not want any indications at all that this car has anything but a stock stereo in it.

First of all, in order to do this, you need a Dremel tool with cutting and grinding bits and the willingness to use it. A LOT of material is removed. If aggressively cutting the dash of your Mercedes makes you nervous, do not attempt this install. The hole in the aluminum dash was selectively enlarged by about 1/4", the vinyl padding was trimmed away from the hole and the steel seam on the firewall was trimmed by about 1/4" or so (the steel gets hot and the paint starts to smoke, make sure you have water and a fire extinguisher handy). The ledge that the grill rests on also needs to be relieved to make room for the speaker rim. The lack of depth on the drivers side requires a 3" or so hole (the diameter of the magnet) to be cut in the top of the air tube feeding the vent. If you measure and cut very carefully, the speaker magnet pushes in to the hole. A few rubber bands around the speaker magnet helps seal it. I checked the airflow after installation and did not notice a decrease.

These are coax speakers with a tweeter built into a bridge over the the larger speaker, so they are taller than a single speaker would be. This makes it difficult for the grill to seat completely. The bridge needed to have the corners rounded in order to clear the grill, and the perimeter of the speaker housing also needed to be ground selectively to make room for the grill. This is a fit, test, grind lightly process that was repeated many times. If grinding on high quality speakers makes you nervous, don't attempt this install.

In the end, it all worked out and the speakers sound awesome. I know some people find MB Quart speakers bright, but I find them to have incredible detail. The tweeters sound great reflecting off the windshield. They are powered by a Arc Audio 70wpc amp running through a Arc EQ.

If you are considering doing this, make sure you are comfortable with cutting your dash. Once you start, you are committed. Work very slowly and carefully. I ended up spending about 12 hours just getting the two speakers in. I'd recommend doing each side on a different day, ideally over a few days, because if you get tired, and the Dremel slips, you could damage your dash in a microsecond.

Hope this helps anybody considering this install. A couple other pointers: I found it easy to run the RCAs and the power wires to the trunk through the plastic channels. Just convince yourself your car needs a good cleaning and remove both front seats and the rear bench and backrest. After pulling up the sills, the carpet lifts easily and running the wires is a cinch. I ran 4 gauge power down the passenger side and the RCAs and amp turn on signal wire down the left side.

Wow, sounds like you worked very hard and came out with a great result in the end!

Since my car has the door speakers, My dash is going to be used for 4 inch mid, then tweeters on the pillars, then 5.25 or 6" in the doors, with 6.5 in the rear seperates.

I will then have the 10" Sub in the sealed enclosure in the trunk, ported up into my cabin.

This is all going to be done later on when I just can't stand the current setup anymore.

Alon

__________________
'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

Now that I've lived with it for a number of days, I would do what you propose. The MB Quart Referenz 5.25" co-axials sound very crisp and clear and I love them, however the mid-bass leaves a little something to be desired. So, I've bought a set of MusicComp crossovers designed for the .75, 4, 6.5 3-way set, and will buy some RWC 160 6.5's and mount them in the door like Michael did on his 300TE (I think it's the TE, could be the coupe.) I will then remove the crossover that came with the coaxs and install the MusicComp. I figure running the 5.25 crossed at the 4" point ought to be fine. The 5.25 coaxs are listed as going down to 50Hz, but even with the amp gains set at half and the crossover at 65ish, they still distort at very high volume. (Kind of a clicking sound.) This is at about 98db+ though. I figure the 6.5's in the doors will fill in the mid-bass and move the soundstage down a little bit. Then I'll discover if 70wpc is enough for this assembled 3-way set. Sure hope I don't have to buy another amp!

Based on my experience, I'd run a 6.5, 4, tweeter set. The MB Quarts I have I got relatively cheap ($215 for coaxs, crossovers and 6.5s) but if I had the funding, I think I'd go with the Boston Pro 6.53 based on all the info I've read. The 4" sure would be a lot easier to get in the dash!

Once I finished the spousal "better to beg for forgiveness than ask for permission" routine, the stealth install requirement went away to some extent. ;-)

The IDQ10 is now mounted in the trunk and sounds fantastic! I'm driving it with 250 watts of clean power and it gets plenty loud. After I put in the 6.5s, I hope to turn down the sub crossover to about 50, it's at 65 now, and you can hear that the sub is behind you and the rest of the music is in front. I removed both rear speakers, but left the first aid kit alone. Certainly enough bass. Please post when you finish your ported sub setup, I'd be curious to know if it results in a tighter sound. My sub sounds a little muddy, I'm not sure why.

Gebhard

WOW, what a coincidence!! That is exactly what I did (and it happened to be the same speakers, too) a few days ago. I was actually planning to post the information here but "Gebhard" did it first. It turned out to be really nice total factory fit, only the driver's side speaker is a little tight because of the limited depth of the hole on this side, since the air vent passes under. It fits good though, although a bit tight. However, I doubt that many other speakers will fit, the MB Quarts have a short depth and that is why they fit. I needed to adjust the fader though, after the installation, since these big speakers are way more efficient than the 4 inch or 3.5 inchers and as a result they bring all the soundstage in the front. So you will need to pull the fader towards the back in order to correct that.

Public Enemy,

But you need all your soundstage up front!

You hardly need rear speakers unless (1) you want rear *fill* in which case you'd have to cross them over differently or (2) you have annoying rear seat passengers that want their fair share of the music cause the sub is relatively too loud for them.

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)

I just wanted to say that rear speakers are not necesarily bad! I run my rear speakers (in my 500E, which has 3 ways in front, 2 ways in back and a 12" sub in the trunk) with a bit less gain then the front, and they do a nice job of filling out the sound (hard to describe). I run them low enought so that they do not detract from the front soundstage, but they do add a little something if tuned properly. And it sounds great in the back seat!

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

That's how to best use the rear speakers. Fade it out enough so you don't actually hear them (you can't localize them) and it just rounds out the sound. Attenuating the highs helps this process a lot. The top of the line, cost no object, engineer's exercise a/d/s/ amps, the PX/a, actually had a switch for the rear speaker outputs for rear fill duties which worked by attenuating the highs just so.

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)