amplifier factory 1.RS-232,ISO,CE 2.digital frequency shifter,LED display 3.2U design is durable 4.Votage: 110V- 240V teaching&educational amplifier Feature/Function:1.It uses the U.S. Chip and BLP digital acoustic feedback technology,2.It can automatically complete the search for whistle frequency acoustic feedback.3.When moving,it can automatically track the sound source,and adjust the MIC ...