Do not run rears full range, rear fill is mid range only. I'd start at 350hz-5000hz to start, then squeeze them in from there...trial and error. I also usually run a very shallow slope around 6db...because what's the point of a steep slope with no transition to another speaker?? For time alignment, a good starting point is anywhere from 12ms-20ms...should add a nice reverb effect and add depth to the music, and maybe some width too. Most people get rear fill wrong and screw up a good front sound stage. You should never actually hear your rear fill speakers and NO, rear fill is not for your rear passengers. Rear fill is the add to your front stage. Your passengers will be perfectly fine listening to the front stage and MOST will never know you have/or do NOT have rear speakers. I usually run NO rear speakers and I have NEVER had a passenger complain about the lack of rear speakers or even noticed. With that being said, I wouldn't worry about putting a high end speaker in the rear doors...an entry level mid range will be fine. Components: If you are planning on a 2-way front stage, (midbass speaker & seperate tweeter) A nice 6.5" like the Morels will be perfect for the front doors. If you were to try a 3-way front stage (mid bass, mid range, tweeter) then I would go with as much cone area as you can for the mid bass as possible....I run 10" woofers in my doors and can go with out my Subwoofer if I desire. Your mid bass plays a pretty small window in the frequency range anyways...say, 60-300hz give/take. The mid range will take over from there on up to the tweeters starting points. Ultimately, how everything sounds is solely dependent on install/tuning/ & clean power. I love Morels when set up for success.
