OK, the good news is, I have started my install!
The bad news is, it has changed somwhat, for reasons I will explain later.
Today, I installed a set of Rainbow Vanadium Cross components into the front doors. They are not playing yet. I plan on running them active, and the amps will be in Phase 2 or 3... so stay tuned.
The Vanadium Cross components use a 10mm.4" midrange that is deeper than I had thought (I was very worried that it would not clear.) I think it is 54mm, but it turns out to fit just fine. Looks like the E90 can take a speaker more than 50mm after all.
There is also a 26mm silk dome tweeter with an integral tuned rear chamber - which makes this tweeter about 1" deep.
The kit comes with passive crossovers but I did not use them. They look like they would be hard to fit in the E90 door (as to most passive crossover boxes.
To mount the woofer, I made some 1/4" MDF rings to match the BMW speaker frames, and I had metal versions of those rings made at a machine shop.
Turns out the door panel is not flat - it curves. So I ended up using gasket foam on the metal rings, and using two rings per speaker. One went up against the back of the door panel with the gasket foam prerssing against the door panel and sealing up despite the curve, then the Vanadium speaker was centered on that ring, then the second ring was pressed over the vanadium speaker's frame, with the gasket foam pressing against the back of the speaker's frame flange.
Here is a pic of the mid without the grille (wanted to make certain to center it on the ring):
The tweeter has an integral flange made out of metal, and there is no way for it to snap into the BMW tweeter tabs. So I cut them out of the way, and mounted the tweeter to the foam insert:
Assembled:
The tweeter's mounting bolt is too long and had to be shortened to fit in the sail location. The foam - plus the thickness of the tweeter compressing the foam - keep the tweeter firmly located.
The tweeter grille in the sail has a layer of foam inserted from behind. I didn't like the idea of the foam - it's been an acoustic problem before - so I removed it. The Rainbow tweeters have a silver edge which would have been visible through the grille, so I masked the tweeter before assembly and painted the flange black.
The sail seems to be shaped as a waveguide for the tweeter after it's backloaded. Interesting shape, glad I pulled the metal grille to look.
While I had the door panel off, I applied some MLV (in this case, VMAX I've had for years) to the back of the door panel and to the outer door sheet metal. Not a ton, just a few pieces - I've believed for years that mass-loaded dampers get 80% of their benefit from covering 20% of the area, and there seems to be more people coming to that opinion now.
I did damp the back of the door pocket and I applied gasket foam to it to see if I could stop any rattles. Car did seem quieter on the way home.
The door pops are very brittle and I will be buying more from the dealer. They are hard to get lined up, but easy to break. Grr. I've taken off hundreds of door panels, and these are real crap. Hondas are tougher.
More posts to come on the amps, the interface/processor, the stealthy subwoofer, and more.