Evans EMAD Batter Clear. The Evans Adjustable Dampening EMAD Bass Drum Head comes with 2 damping rings, each of which affects the head's sound and pedal response. EMAD stands for Externally Mounted Adjustable Damping and this external system maximizes natural attack characteristics. It offers tremendous dynamic range (even at low dynamic levels where other systems fall short). It also allows quick, easy adjustments without having to remove the head from the drum an especially valuable feature during recording sessions.