[hydrashok]

Gotcha! Is this what you mean:
Seal all the openings in the door with damping material except the opening for the mid-bass. That way, because the midrange is outside the sealed door, and because the rear-wave of the mid-bass goes into the sealed portion of the door, the mid-bass won't be affected.

Am I right?. If so great, :-) as this is easier to get done. And I think this is what Zuheimi is doing.