The AMT B811 are a matched pair of cardioid condenser microphones suited for capturing drum overheads, stereo ambiance, piano and more. When used in pairs, the microphones accentuate cymbals accurately, while the cardioid pattern allows for a good rejection rate outside the perimeter. The B-811 operates on phantom power from 15 volts to 48 volts DC, an LED indicates status of power (on/off and voltage). The flat frequency response allows for a wide array of applications, the B811 is AMT's stereo piano solution.