"Invisible" audio for the Porsche 914 Options

[horizontally-opposed]

Plans to go for a drive in my 914 this weekend were dashed by yesterday's stay-at-home alert, so I finally dug into a minor project I've been putting off: Rebuilding the car's 28-year-old audio system. While it performed well for 15-20 years, a mixture of age, heat, moisture, etc eventually caught up to it.

System goals: 1) Install a system powerful enough to be enjoyed with the top on or off; 2) maintain/improve "period correct" appearance with no head unit and, if possible, no visible speakers; 3) minimize weight; 4) avoid or minimize additional holes/etc.

I'm going into this with the understanding that it's entirely possible the exercise will be futile with a 2.2-liter flat six, but I have been collecting the parts over time and figure it's worth a shot. Some of this stuff has been sitting for years and thus may not be available anymore—but plenty of alternatives are.

Old system components:
Tape cassette head unit Smartphone flopping around on seat > EQ
Pyle graphic EQ turned on/off by factory rear defrost switch
Pioneer fan-cooled amplifier (~1991)
Boston Acoustics four-speaker set in doors (~1991)
Pioneer ducted bass wedge in passenger footwell

New system components:
Smartphone with a proper mount > EQ
Blaupunkt five-channel parametric EQ
JL five-channel amplifier
JL six-speaker set for factory speaker enclosures and door
?? subwoofer in passenger footwell (prepare for now, add later)

Fair warning: This thread may proceed at a glacial pace, as midlife plus a small business means my days in the garage are fairly rare in this chapter. I'm also figuring this out as I go, and will use this thread as a journal and a place to share ideas.

[horizontally-opposed]

The mids & tweeters will easily fit into the factory enclosures with the recommended 3.5- to 4.0-inch distance between their centers.

The door speakers will be trickier. The "pro" installers butchered my inner doors back in 1990~. While it's surprising how rigid the doors remain, I'll have to cut even more steel to get the new 6.5s in the same way. So I'm looking to see if I can mount the 6.5 from the other side. (I've never liked the way the speaker has to be pulled to remove the door card, or the way it pinches the door card.) Turns out the 6.5 can be maneuvered into the door, and could be securely held there with three mounting bolts. A curved (3D-printed?) plastic "mounting ring" (1/2 to 2/3rds of one anyway) would add rigidity and aid with sealing, while a Metra cover would protect the back of the 6.5 from rain water. Also thinking about custom cut styrofoam to close the 6.5 into the oddly shaped relief.

Short term, I'll simply bolt my old Boston Acoustics speaker grille to my existing door card, but I have a pair of ABS door card backings from 914Rubber and am thinking about "venting" the 6.5s through holes punched into the depressions in new basketweave over holes drilled into the ABS door card. Not sure this is viable, but it would allow for invisible 6.5s—much like the factory speaker holes seen in early 928s and a variety of other models… (IMG:style_emoticons/default/idea.gif)

[BillC]

The mids & tweeters will easily fit into the factory enclosures with the recommended 3.5- to 4.0-inch distance between their centers.

The door speakers will be trickier. The "pro" installers butchered my inner doors back in 1990~. While it's surprising how rigid the doors remain, I'll have to cut even more steel to get the new 6.5s in the same way. So I'm looking to see if I can mount the 6.5 from the other side. (I've never liked the way the speaker has to be pulled to remove the door card, or the way it pinches the door card.) Turns out the 6.5 can be maneuvered into the door, and could be securely held there with three mounting bolts. A curved (3D-printed?) plastic "mounting ring" (1/2 to 2/3rds of one anyway) would add rigidity and aid with sealing, while a Metra cover would protect the back of the 6.5 from rain water. Also thinking about custom cut styrofoam to close the 6.5 into the oddly shaped relief.

Short term, I'll simply bolt my old Boston Acoustics speaker grille to my existing door card, but I have a pair of ABS door card backings from 914Rubber and am thinking about "venting" the 6.5s through holes punched into the depressions in new basketweave over holes drilled into the ABS door card. Not sure this is viable, but it would allow for invisible 6.5s—much like the factory speaker holes seen in early 928s and a variety of other models… (IMG:style_emoticons/default/idea.gif)

Hopefully this is just a silly question, but have you checked to see if the roll-up window will clear the door speaker when rolled all the way down? Back in high school, I saw plenty of home-grown speaker installations that had collision issues with various moving parts (window, door stay arm, etc.).

A suggestion for an alternate door speaker install:
Install the speaker on the inside (passenger compartment) side of the door sheet metal (like it looks like how your old speakers were installed. Then, trim the door panel to clear the rim of the speaker. Finally, install the speaker grill to the face of the door panel. This should give you more clearance inside the door shell for moving parts and still let you remove the door panel without having to remove the speaker first.