The design of the ECM-66B yields clean, natural reproduction of musical instruments while maintaining excellent isolation from the acoustic environment. Unlike most miniature microphones, this mic has a uni-directional polar pattern, carefully contoured for better control of feedback. The higher voltage supplied to the microphone by the built in DC to DC converter increases the maximum input sound pressure level to an amazing 130 dB SPL.This special construction also complements the electret condenser design, resulting in excellent transient response and thus better tonal quality. For added versatility, the ECM-66B can be powered by a single AA battery or external 48 VDC. The battery on/off switch on the power supply helps save the battery. An LED illuminates to show battery condition when power is turned on. A uni-directional miniature microphone developed specifically for recording musical instruments and voice when superb rejection of the ambient sound is desirable, the ECM-66B wil