The high Qes value coupled with low efficiency. The damping makes broader but less high resonance. If the resonance frequency is low, not able further compensate the dipole roll off. If you leave the Qts high, "one note bass" is generated around resonance, and a big hole at upper bass region (a lot of full range static make it). At planars can implement a mechanical damping plus electrical dipole roll-off compensation. For example, at the bigger panel's (35Hz) must damp (Qts=2) and add a low pass filter with cca. 50Hz corner frequency. The efficiency will terrible, but the bass can be well controlled. The setup must be variable (Q and corner freq.), controlled by ear.
