I've been meaning to do this for a long time but got too busy and pushed the project aside for awhile. I've had these ADMWs in my possession for about 8 months now and I figured its time to get this going.
The Morel ADMWs have been installed in the underseat enclosures in many 1-series and 3-series cars by VP Electricity and others but VP did mention that for some reason, the M3 doesn't have quite enough clearance under the seat to make it a straight forward install. I can confirm that he his correct. I suspect that might be why he has started to use the Jenhert woofers now which are pretty much drop in replacements for the OEM woofers. Since I already had the ADMWs, I figured I would give it a go anyway and see what happens.
The procedure of installing the SWS-8s are well documented so I'll start with the removal of them.
Here is the OEM underseat grill hiding the SWS-8s. You can see how clean and factory it looks. No one would ever suspect there is something aftermarket under there.
With a finger ratchet, I removed the 6 phillips screws securing the grill. The finger ratchet is a great tool for small confined spaces and also for making sure you don't over torque small screws.
With the grill off, you can see the binding posts I installed when I did the SWS-8s to make it easy to remove if need be.
After removing the 2 nuts securing the enclosure to the car, I pulled the enclosure out of the car and here it is ready to be disassembled.
After removing the SWS-8, I have the 3/4" thick MDF spacers made by forum member jtsherri. The spacers were delivered unfinished so I painted them black to blend in. I also countersunk the holes where the spacers get screwed into the enclosure. This is necessary otherwise the heads of the screws will get in the way of the mounting frame of the ADMWs. You can also see the pigtails I wired through the spacer for connecting the wiring. There are female terminals on the inside and male terminals on the outside to connect to the wiring from the amp. I didn't use binding posts here because they stick up too far and would interfere with the seat rail.
Here is what the enclosure looks like with the spacers and ADMWs installed. Again, you can see the male ends of the pigtails coming out of the enclosure. The holes the wires pass through are sealed from the inside with epoxy plumbers putty. It is soft and workable for a minute allowing you to press it into the hole and then hardens. The cured putty is water tight and air tight.
Here is the ADMW with the grill installed. I actually found it easier to install the grill after you put it in the car otherwise the grill gets in the way. It is also only pressure fit into the frame so it will end up falling off when you're trying to get the enclosure back into the car.
The enclosure is now installed back into the car. Notice how I had to roll back the carpet so it doesn't sit on top of the grill. This needs to be done because there is not enough clearance between the seat and the floor that will allow both the ADMW grill and the carpet to fit under the seat rail. If you try to force it, the seat rail will crush the grill when you reinstall the seat and the woofer cone will hit the grill. You'll hear a pretty loud popping sound if you push the grill down too far. Ask me how I know
Here you can see the clearance (or lack of clearance) between the seat rail and the ADMW grill after it is installed. The rail is actually crushing the grill a little but there is enough clearance between the grill and the cone of the woofer to allow the grill to be depressed a little without affecting the movement of the woofer. A 1/4" spacer under the seat rails might have helped with this but that still wouldn't be enough to get the carpet in.
I did do some listening with the ADMWs installed and right away there are a few things noticeably different from the SWS-8s. The midbass on the ADMWs is much cleaner. There is less resonance in the upper midbass notes between 80 and 150Hz. The SWS-8s would resonate really bad in that area so I had to turn down those frequencies to compensate. Now, I have no issues in that area. The ADMWs do not go as low as the SWS-8s though. That was obvious with any material that had an orchestra in it. The low notes from the tympany would cause the ADMWs to bottom with the 25 Hz subsonic filter I had setup for the SWS-8s. Moving that subsonic filter up to 40Hz helped eliminate that but I will definitely need to look into getting a trunk sub now.
So, they do work but not without a good amount of work to get them in there. My opinion, if you're not planning on putting a sub in the trunk, stick with the SWS-8s. If you are planning for a sub, the ADMWs can work but its definitely not drop in. Are the benefits worth the effort? I would have to say, I don't know. I've never heard the Jenherts so if those give the same sonic benefits that the ADMWs do, I would say that is the way to go. Sound wise, I have no issues with the ADMWs but if there is something out there that sounds just as good and is easier to fit, I think that would be the winner in this case.
BTW, I gotta say thanks to jtsherri for making those spacers for me and of course to VP Electricity for helping me out when I had a problem with the ADMWs. VP also shared a lot of his technical knowledge with me about how he got these to work in other cars. Without his help, I probably would have abandoned this project months ago.