New chapter: Audio mod.
My Limited has the factory JBL audio system. That means a dedicated amp that fires audio to six speakers and sends also a line voltage to the subwoofer in the rear door.
That JBL amp has integral cross-over filters for the front door speakers, that I kinda of... hate how it sounds. I like pop, soft-rock, and classic rock music and the whole car sounded like was meant for a bass head (house, hip-hop). Even if the head-end radio has separate adjustments for bass, mid and treble, I still can't make it sound decent (for my ear).
I downloaded an app "Audio Tester" that can output a frequency sweep from the phone - input that into the AUX port and see what's up.
What's up is that the sub is over driven. And the front door crossover happens around 550Hz. There is a huge "gap", with lower output between 600Hz and about 3-5kHz. Then it's a huge "hump" at around 9kHz (that some people might confuse with high frequency) and then the response drops down again. Never saw something like that. I tested it with the door open, too, to eliminate any car resonances.
Lover freq, below around 550Hz (slow slope, don't imagine a sharp cut-off) goes to the 6-1/2" lower speaker and the freq higher that that go to the upper "speaker". That is actually not a speaker, but an 1" tweeter!!! In no universe that can go below 2kHz. So that explains a lot of what I was hearing.
I research a lot and I settled for the
JBL GTO 329 3.5" speaker,
$45 for pair on Amazon. Why? Because they are low impedance (nominal 3 ohm, same with the OE speakers), two way (85Hz-21kHz), and they're just a smidge bigger than the door's round cutout.
Also they have a very useful "cylinder" raised lip that will help with setting them flush against the door panel. Weird is that the model shown on their side doesn't show that cylindrical "horn", but Amazon link has the correct pictures.
Of course that means that I should fabricate a new "support" for them. Well my hardware store has this rolled flat mattal band, with holes, used to support plumbing piping and HVAC ducts... awesome to make brackets (double it up to give more stiffness). The speakers needed some wires (audio cable AWG #16, same hardware store), some small bolts and nuts (1/4"), some female audio terminal disconnects (gold plated, 7/64" Autocraft 84547 and .187" Dorman 84546), my crimping tool, solder iron, thermo-shink tubbing, a video from youtube that shows where the screws are in the door (2 long ones in the handle that I use to pull the door shut and one short that holds the manual release lever on the door face).
After some struggling and manipulating those brackets to get to the right point, followed by fitting the door panel over to see if it aligned with the hole, I managed to get them aligned and thigh against the door panel when installed.
They are not perfectly concentric, but because the speakers are slightly larger, that's not an issue. I actually arranged them so there is the sound is more directed towards the passengers, not towards the dash.
I didn't install the series capacitors that came with them because the output is already filtered.
Audio quality feels much, much better and the frequency test sweep is definitely more linear. Sadly I tried to save the old sweeps within the app, but it didn't work. I knew I should had used screen-shoots...
I would add a note: There is no point to "upgrade" the lower mounted speakers (the 6-1/2" ones). Those are perfect for the limited audio range that is sent to them, basically they are used only as woofers.
See the JBL system diagrams below.