Active humbuckers have a distinct sound - powerful, clean, open sounding, with excellent harmonic overtones and very tight lows.  The down side for many players is that they also sound cold, have limited dynamics and run out of headroom when played hard.  And of course, they need batteries.  In 2006, DiMarzio took a close look at the most popular active neck and bridge humbuckers to see if they could capture all of the good qualities and eliminate the disadvantages.  The D Activator neck and bridge models are the result.  They have the same loud yet clean sound, as players of active humuckers are familiar with, and killer harmonics.  They also respond instantly to hard or light pick attack.  In a word, they rock.  And they don't need batteries.