Shure A15HP - In-Line Hi-Pass FilterThe Shure A15HP in line filter passes mid and high frequencies while reducing low frequencies. The A15HP helps to eliminate electrical and mechanical noise in an audio system such as 60Hz electrical hum from AC power lines, low frequency rumble caused by wind noise or air conditioning system, and stage floor noise transmitted to a microphone through the microphone stand. The A15HP affects frequencies below 100 Hz. When connected to the microphone