Woofer unloads above tuning only when the cab is sealed?

[slowfkncar]

Ok so i have something strange going on that I've neved experienced before, i have just built up a new system for my new work vehicle and i notice my woofer kinda just unloads "pop/crack"  around 50-70hz only when my car is sealed up (windows up), the second i roll the driver window down the popping goes away mostly untill very high volumes, if i drop both front windows then it completely goes away with no unloading/bottoming out at all. I have tried dropping box volume down to 1.67net and while obviously my higher freqs got more punchy the unload problem is still there but not as bad and once again completly gone once my windows drop. I believe the problem may possibly be my custom tight gap zv3 woofer which i can drive to retarded amounts of excursion even at tuning but it only happens when my windows are up lol weird.. I can try swapping woofers to an fi-q, zv4 or alpine type x but not if i dont need to. 

 

Box gross 3.09

Box net 1.97 w/woofer loaded (i have added .40 to drop volume for testing down to 1.6 net) but still getting crazy excursion and bad cone control with windows up.

28sq.inch of port @ 32hz, 14.5 port area per foot.

Using an older dual input aq3500.1

Woofer is a zv3 motor with the newer style BTL softparts with a high xmax coil, i had random old shit  laying around and decided to just slap it together for the hell of it. 

Anyone got any explanations?

 

 

[ShadeTreeMechanic]

I remember svc 15 and 18 subs buzzing with upper bass back in the day. Is the voice coil centered in the gap? Sounds almost like the coil was too high when it was put together.

Edit: maybe someone who builds subs can tell us if that could cause your problem for sure.

[slowfkncar]

16 minutes ago, ShadeTreeMechanic said:

I remember svc 15 and 18 subs buzzing with upper bass back in the day. Is the voice coil centered in the gap? Sounds almost like the coil was too high when it was put together.

Edit: maybe someone who builds subs can tell us if that could cause your problem for sure.

It reminds a big sealed box untill i roll the windows down lol its annoying. The gap is a little tight too,much longer coil also(60mm vs 52mm), but nothing like my old spl soft parts from sundown. I guess I'll need to swap woofers to know for sure. Would be nice if i could get away with some frankenstein shit that would have been binned if never used.