Power Module (Discontinued by Manufacturer) Audio-Technica AT8531B The Audio Technica AT8531B is an in-line body-pack power supply for AT series gooseneck and overhead microphones. The unit is designed to supply 9 to 52V phantom power and uses AA batteries. A low frequency roll-off switch is provided and minimizes structure and wind noise and a belt clip provides added stability. The unit features a TB3-male input and standard 3-pin XLR-male output connector.