i mean A BSC type circuit (low pass inducror with resistor in parallel), not necessarily set for the baffle loss frequency, but maybe higher (in my example maybe for the frequency = the max coming from the vent) My rationale was that maybe the distance differences between the ear-vent and the ear-driver can combine with the inductor phase shift (for the frequencies below the filter) and the acoutic phase shift (becuase of the box) to actually make it sound more in-phase... -akhilesh