Continued from Post #219...
It's taken some patience, but I finally figured out how I want to mount the custom crossovers. I ditched the enclosure idea. I created oem-like harnesses using felt tape, a brady labelmaker, and oem connectors/pins/sockets. I'm going to mount the crossovers as shown using high strength 3M Advanced Adhesive Velcro and tape the harness bundle at the label with gaffer's tape to stress relieve the wires at the XO. Installation schematic shown.
UPDATE: [12DEC2021] - I've installed three crossovers and finished completing the harnesses on all five XOs. The three installed are located in the rear doors and I one in the center channel. I had a filtered B&W tweeter in the center channel, but replaced the tweeter with B&W without filter and installed the XO. When I compare the XO's to existing speakers three things are very obvious: 1) The B&W speakers in the rear doors are quieter than the front door S752 Individual Speakers. This is because the resistance of the B&W speaker pair is almost double than the S752 individual speakers. 2) The S752 individual speakers high frequencies are quite muddy. High frequency is loud and clear in the B&W. 3) Sitting in the rear seats the D-Pillar B&W's, where I used filtered B&W tweeters, sound significantly different than the rear door speaker set. And not for the better. This tells me I need to install XO's in the D-pillars so it matches the rear door setup.
Sitting in the front seat, the overall sound is enjoyable in this state, but you get the feeling (hearing clarity from rear area) it can be better. I'm currently running bavsound underseat subwoofers. The low end is likely not as clear as the B&W subs, but these are contributing nicely to the overall sound. I'm not at a want for bass and coupled with B&W mids, the midbass is tight. Note that I have the OEM equalizer set FLAT, which is critical. I have been primarily playing my lossless music files through the Android infotainment system, coupled with my USB DAC upgrade. The USB Audio Player Pro (UAPP) gain and equalizer allows me to make much finer frequency adjustments than OEM and I'm fairly certain the DAC and the UAPP attribute to the sound significantly. I can definetly say that the Android DAC Setup plays music at level above the OEM sound. STILL, you can't help wonder how much better B&W subs would sound...I have plans to upgrade to B&W subs if needed and once I finish the XO install.
The S752 Individual Speakers are great, however as I mentioned before, the "muddy' problem is likely that OEM capacitor/filters in the system are aging badly and likely aren't high end components to start. I've tested this degradation and it's tangible. It affects all the tweeters, except in the front doors. The front doors have an oem crossover and that's where the capacitors are for the front door system. I looked at adding the oem crossover to the rear doors and if you make a pigtail, this is easily doable. Instead of redoing my system back to the S752 level, I decided to go with this custom XO route and new B&W speakers. It also allowed me to request the highest end electrical components available from the fabricator for the XO build.