Magnificent work, Darren. I was hoping to do a deep dive into speaker solutions myself at some point, and your post is very inspiring to me!
Have you ever seen the 300SL/Adenauer speaker grilles? I often thought they might be cool to use in lieu of the rather ugly W113 speaker grilles that are placed down in the foot well. It also confuses me why Mercedes wouldn't just match the handsome wooden grille on the dash with something with a similar aesthetic down below. Looks like an afterthought.
I often think that one could get the chassis of an AC unit and retrofit it with speakers, perhaps using nice wooden grilles.
I've seen various period photos of aftermarket sound systems and radios and such often mounted under the dash, just like you have done. This one is by the Schaub-Lorenz company. They were a good manufacturer of transistor radios back in the 50s/60s that sadly has been reduced to a shell of itself, one of those trademark names that gets applied to cheap generic goods, like Westinghouse. How sad. Anyway, I think they and others like them look cool under the dash there.
I also feel one could sacrifice the heater vents for speakers. It's a nice place for them. Mercedes certainly made better use of the center console area on the 107. I don't agree with the material choices as they felt cheap and look cheap, but the design is pretty good. E9s, E-types, and the DB6 all used that space for some speakers on the sides.
Note speaker location here on the BMW:
Another idea I've seen on some Porsches is hiding them inside of the map pocket in the door. Underneath the armrest is a pretty cool stealth spot, I think. Only works if you have the superior hard-sided pockets, of course, and not the loose lame bags of the later cars. Yet another stealthy spot is inside of the seats with the escutcheon on the back working as the speaker grille of sorts. Unfortunately there just isn't a good place for tweeters unless, again, one is willing to cannibalize the heater vents. Lastly, should you not have AC, one perhaps could put some under the dash with some holes cut out of the underdash panels (covered with a cloth of course) to allow for the flow of sound.
Anyway! Can we get some close-ups of the knobs, please?
