Hello, Sorry about my absence to your questions. The weekend was busy and I am shipping out more drivers every day. I am simply referring to the majority of drivers that have a single gap and a long voice coil. They usually exhibit a parabolic BL curve as a result of their motor design. Thanks for the further clarification on motor linearity Mark. I sent drivers out to DUMAX for testing, so we should have some more detailed xmax and motor linearity information available soon.