An ultrasonic surgical instrument includes a body such as a handle assembly and an acoustic transmission assembly. The acoustic transmission assembly includes an ultrasonic transducer and an end effector. A mounting ring is positioned on a horn of the transducer. A rotatable drum is positioned distal to the mounting ring. Piezoelectric components of the transducer are positioned proximal to the mounting ring. Electrical conduits extend from the drum to the piezoelectric components and are routed over or through the mounting ring. The drum is coupled with a power source through a slip ring assembly to selectively activate the transducer.