...lessons learned installing Kenwood, Alpine, Image Dynamics Audio Into a Double Cab

DevL, my ID drivers/tweeters in front also have physical crossovers mounted to the back of the amp board (so I made them conveniently aweful to get to!), each with multiple adjustments of their own. Combine that, plus all the variables you have mentioned, plus the fact that the Kenwood system requires you to MANUALLY set all the above FOR EACH AND EVERY INPUT method and the notion I'm gathering that in general Tacoma Double Cabs are just wonky to tune.....ugh, this will take awhile.

My sensitivity to weight really comes from my other automotive-based paycheck squanderer...where a 100 lbs is a major major deal in lap times!...somewhat misplaced here. Please tell me more about the distinction you made between "vibration dampener" and "mass loaded"....I am not expert in the audio realm and am ignorant of the two options. I had made an assumption that Ballistic was mass loaded because it has a density far in excess of plain butyl rubber (and the aluminum foil covering is not a meaningful contributor to that weight, AND I didn't find good technical data on its performance or characteristics) and is actually closer to the density of mass loaded vinyl sheeting, but I still have not seen that claim made by Metra. What product did you use? I also haven't been able to find dB/Hz specs for Ballistic, but the specs for the vinyl are Very impressive....I confess I made an assumption about Ballistic and decided to go with it.

 

Mass loaded vinyl is a sound blocker. It physically block sound and is isolated by closed cell foam so its decoupled from any panels or skins. Its a substitute for lead sheeting used in the limo industry or sound proof room industry. Vibration dampners or Constrained Layer Dampner has butyl rubber (prefferably) or asphalt based compound (less desirable) that has adhesive on one side and a layer of aluminum foil on the other. It is used to stop metal panels from vibrating or resonating. Its placed directly on metal panels. I got my material from sounddeadenershowdown.com and it explains all the materials in detail on that site.

 

Another thing I have noted is that some crossovers are designed so that the woofer and tweeter are out of phase at the crossover point to cut peaks in the opposing driver or are supposed to reinforce each other at the crossover point; however as distace of the woofer to tweeter changes, it is possible that what was in phase is now out of phase. So there is no real definant correct phase relationship for woofer and tweeter for a particular component. My Focal components needed the tweeters and woofers out of phase from each other IN MY FRONT DOORS. It could be different in a different vehicle. My sub location required my rear speakers and sub be out of phase from each other. Different speakers or different sub locations will be different. Different components may be different too.

A bad thing I have noted is that the SRS WOW features that many head units use actually not only mess with EQ settings and echo effect, but also change phase at certain frequencies to get their effects. That screws up your phasing if you try to phase after setting any SRS effects.

I think once my speakers are phased propperly (which I think they are) I am going to need to get a RTA and do my EQing and THEN add any SRS effects I may want.

I think the best way to attack EQing is to do the fronts seperately from the listening position, do the rear seperatly from fronts from a middle listening position and then run both together, measure from the front, and bump some higher end from the front (since the rear gives little high end due to the seats blocking the higher frequencies)... it will help bring the sound stage up and forward to boost the mid and upper end on the final step. Just my guess at this point.