I've been messing with the tune in my 2018 Challenger off-and-on for a while as I continuing to learn and experiment - and I think I have it sounding pretty damn good - especially considering that I don't have any "real" subs and that I am using inexpensive speakers in stock speaker locations. Here are the REW frequency response plots from all speakers (Dash, door, rear-deck, sub and all together). I was able to get the little 8" sub (entire powered enclosure is less than 3" in height!) playing down to about 35dB while being pretty flat.
You'll notice the "unnatural" looking "bumps" in the door/dash responses. Those were needed to overcome what I assume are phase-related issues in the overall response - in order to keep the response flat in some areas. Without them, I would have dips at those locations when both L and R speakers are playing together. I also have a pretty big "notch" carved out between 2k and 5k - in my opinion, that was the key to getting the system sounding "correct" - otherwise, it was just too "harsh" and "in your face" at those frequencies. May just be related to my hearing though - not really sure. I also overlap the sub and midbass speakers a little just to add a little more "uummph" in the bass department. Using 24dB LR slopes on all crossovers.
I'm curious to hear some feedback - both on the overall response curve and even if using EQ to overcome the "phase-related dips" is the "proper" way to address those issues when both L and R speakers are playing together. As long as the overall response with all speakers playing is good, should I really be concerned with "unnatural" response caused by the EQ on the individual speakers to overcome those phase-related dips when both L and R speakers are playing together (assuming that is what causes them)?
Any other feedback on anything? I really like hearing constructive feedback as I have a lot to learn! Anything that sticks out as being obviously "wrong" or not "optimal"? You won't hurt my feelings. :-)
Thank you.