I figured out a super cool way to completely solve the 80hz dip.
First off the dip isn’t as bad as you think once the room gain from sub is eq down.
However it’s still there, just 6db deep instead of 18db deep.
By adding a small woofer in the center of the car the dip is gone. However finding a place to put it sucks and the sound is localized if made too loud. Careful dsp and delays should be used and it can mostly vanish.
Bass has lots of impact and frequency responce is great. So basically under the armrest/console. I decided not to do it. If I had a full-size truck or car that has a big center console I would be in order.
The Bose system in 2003-2017 Chevy/GM full-size truck/suv has a 5” DVC sub in the center console, that factory sub sounds so good and are almost indestructible. That would be the next best thing as it’s in the middle but it’s up front.
I think I’m going to explore using a pair of Dayton ND-91-4 3.5” woofers with 4.5mm one way xmax and 11mm Xsan and do a small sub under each seat firing up against the center console placed as far forward as possible to reinforce that dip would make a great way to fill that dip fully and completely.
That will be the next feat after this is done.
Getting a extremely short bandwidth linear phase 48db filter would not be too difficult to pull off. A single 2x4hd would do the job,
With rephase and center the impulse at about 16ms. Would take some clever reading of measurements and being a good listener to get the blend to work good, as it’s not a summing driver but a reinforcement driver it will want to be localized easily.
It’s worth the venture if big wide cars
