The MI-3111 is an exclusive preamplifier for 1/2-inch back electret-type microphone, which is applicable to CE marking*1. The MI-3111 also conforms to EMC so that it has high tolerance for noise. Featuring constant current operation, with a BNC input, thereby improving its ability in connection. Various types of instruments such as amplifier, instruments and data recorder with CCLD*2 can be connected directly.